426 Sentences With "reactant" | Random Sentence Generator

They also have fairly complete documentation which makes it easier to pick up Reactant and start programming.

Just when you thought it was safe to go back to Xcode, a small Czech team called Brightify has created Reactant, a framework that makes it easy to program iOS apps.

Sizmann went on to explain how a reactant releases oxygen, which is then brought into contact with water and CO2, where the oxygen is "reclaimed" and hydrogen and carbon monoxide are left as products for output.

Reactant and Product are materials that both contain the element X, and X has two stable isotopes, AX (the heavy isotope, with a mass of A) and BX (the light isotope, with a mass of B). The fractionation factor for the element X in the reaction Reactant → Product is represented by the notation AαProduct/Reactant. AαProduct/Reactant is calculated as follows: AαProduct/Reactant = (δAXProduct \+ 1)/(δAXReactant \+ 1) Fractionation factors can also be reported using the notation AεProduct/Reactant, which is sometimes called the "enrichment factor" and is calculated as follows: AεProduct/Reactant = AαProduct/Reactant \- 1 Like δ values, ε values can be reported in per mille by multiplying by 1000.

The most commonly encountered form of chemisorption in industry, occurs when a solid catalyst interacts with a gaseous feedstock, the reactant/s. The adsorption of reactant/s to the catalyst surface creates a chemical bond, altering the electron density around the reactant molecule and allowing it to undergo reactions that would not normally be available to it.

In a chemical reaction, a reactant is considered to be in abundance if the quantity of that substance is high and virtually unchanged by the reaction. Abundance differs from excess in that a reactant in excess is simply any reactant other than the limiting reagent; the amount by which a reactant is in excess is often specified, such as with terms like "twofold excess", indicating that there is twice the amount of reactant necessary for the limiting reagent to be completely reacted. In this case, should the reaction go to completion, the quantity of the reactant in excess will have halved. When performing kinetic or thermodynamic studies, it is often useful to have one or more reactants in abundance, as it allows their concentrations to be treated as constants (or parameters) rather than as variables.

1,1-diiodoethane is commonly used as a reactant in reaction such as SN2. The following are some examples of SN2 reaction using 1,1-diiodoethane as a reactant."1,1-diiodoethane", Chemsink. Retrieved on 8 June 2017.

In dearomatization reactions the aromaticity of the reactant is permanently lost.

In complexation catalysis, the term passive binding refers to any stabilizing interaction that is equally strong at the transition state level and in the reactant-catalyst complex. Having the same effect on the stability of the transition state and the reactant-catalyst complex, passive binding contributes to acceleration only if the equilibrium between the unassociated reactant and catalyst and their complex is not completely shifted to the right. It was defined by A.J. Kirby in 1996 as opposed to the dynamic binding, i.e. the whole of interactions that are stronger at the transition state level than in the reactant-catalyst complex.

In redox reactions one reactant, the oxidant, lowers its oxidation state and another reactant, the reductant, has its oxidation state increased. The net result is an exchange of electrons. Electron exchange can occur indirectly as well, e.g., in batteries, a key concept in electrochemistry.

In subsequent steps, the activation energy is only from the intermediate to the next transition state. Reaction coordinate diagrams also give information about the equilibrium between a reactant or a product and an intermediate. If the barrier energy for going from intermediate to product is much higher than the one for reactant to intermediate transition, it can be safely concluded that a complete equilibrium is established between the reactant and intermediate. However, if the two energy barriers for reactant-to-intermediate and intermediate-to- product transformation are nearly equal, then no complete equilibrium is established and steady state approximation is invoked to derive the kinetic rate expressions for such a reaction.

A slurry reactor contains the catalyst in a powdered or granular form. This reactor is typically used when one reactant is a gas and the other a liquid while the catalyst is a solid. The reactant gas is put through the liquid and dissolved. It then diffuses onto the catalyst surface.

The Creighton process involves the hydrogenation of a 6 carbon chain aldehyde.H. I. Creighton, Trans. Electrochem. Soc. 75, 301 (1939) The reactant is 2,3,4,5,6-pentahydroxyhexanal (an aldehyde) and the product is 1,2,3,4,5,6-hexanehexol (an alcohol). The product thus has two more hydrogen atoms than the reactant: -CHO is replaced by -CH2OH.

This type of model is valid for the non-premixed combustion, but for the premixed flames the reactant is assumed to burn at the moment it enters the computation model, which is a shortcoming of this model as in practice the reactant needs some time to get to the ignition temperature to initiate the combustion.

In this method the chemical equation is used to calculate the amount of one product which can be formed from each reactant in the amount present. The limiting reactant is the one which can form the smallest amount of the product considered. This method can be extended to any number of reactants more easily than the first method.

However, if the entire diazonium solution is added all instantaneously then semiconducting SWNTs will also react due to presence of excess reactant.

Once it cools, a bond is formed. From welding together train tracks to entering bank vaults, solid reactant welding has many niche uses.

Lewis acids are used to catalyse a wide variety of reactions. The mechanism steps are: # Lewis acid forms a polar coordinate with a basic site on the reactant (such as an O or N) # Its electrons are drawn towards the catalyst, thus activating the reactant # The reactant is then able to be transformed by a substitution reaction or addition reaction # The product dissociates and catalyst is regenerated Common Lewis acids include aluminium chloride, ferric chloride and boron trifluoride. These reactions are usually carried out in organic solvents; AlCl3, for example, reacts violently with water. Typical solvents are dichloromethane and benzene.

Instantaneous selectivity is the production rate of one component per production rate of another component. For overall selectivity the same problem of the conflicting definitions exists. Generally, it is defined as the number of moles of desired product per the number of moles of undesired product (Definition 1Fogler, H.: "Elements of Chemical Reaction Engineering", 2nd Edition, Prentice Hall, 1992). However, the definitions of the total amount of reactant to form a product per total amount of reactant consumed is used (Definition 2) as well as the total amount of desired product formed per total amount of limiting reactant consumed (Definition 3).

For zero-order reactions, the reaction rate is independent of the concentration of a reactant, so that changing its concentration has no effect on the speed of the reaction. Thus, the concentration changes linearly with time. This may occur when there is a bottleneck which limits the number of reactant molecules that can react at the same time, for example if the reaction requires contact with an enzyme or a catalytic surface. Many enzyme- catalyzed reactions are zero order, provided that the reactant concentration is much greater than the enzyme concentration which controls the rate, so that the enzyme is saturated.

Different solvents can affect the equilibrium constant of a reaction by differential stabilization of the reactant or product. The equilibrium is shifted in the direction of the substance that is preferentially stabilized. Stabilization of the reactant or product can occur through any of the different non-covalent interactions with the solvent such as H-bonding, dipole-dipole interactions, van der waals interactions etc.

Collisional excitation is a process in which the kinetic energy of a collision partner is converted into the internal energy of a reactant species.

Historia, the Association of the understudies of History, is lively going about as a reactant operator in drawing out the inactive gifts of our understudies'.

Spin- forbidden reactions are one type of non-adiabatic reactions where at least one change in spin state occurs when progressing from reactant to product.

The photon can be absorbed directly by the reactant or by a photosensitizer, which absorbs the photon and transfers the energy to the reactant. The opposite process is called quenching when a photoexited state is deactivated by a chemical reagent. Most photochemical transformations occur through a series of simple steps known as primary photochemical processes. One common example of these processes is the excited state proton transfer.

The HOCl byproduct, itself a reactive oxidizing agent, can be a problem in several ways. It can destroy the NaClO2 reactant: :HOCl + 2ClO2− → 2ClO2 \+ Cl− \+ OH− making it unavailable for the desired reaction. It can also cause other undesired side reactions with the organic materials. For example, HOCl can react with double bonds in the organic reactant or product via a halohydrin formation reaction.

For physical reasons, it is usually assumed that reactant concentrations cannot be negative, and that each reaction only takes place if all its reactants are present, i.e. all have non-zero concentration. For mathematical reasons, it is usually assumed that V(x) is continuously differentiable. It is also commonly assumed that no reaction features the same chemical as both a reactant and a product (i.e.

Many strategies exist in chemical synthesis that go beyond converting reactant A to reaction product B in a single step. In multistep synthesis, a chemical compound is synthesised though a series of individual chemical reactions, each with their own work-up.Advanced Organic Chemistry Part B: Reactions and Synthesis Francis A. Carey,Richard J. Sundberg Springer 2013 For example, a laboratory synthesis of paracetamol can consist of three individual synthetic steps. In cascade reactions multiple chemical transformations take place within a single reactant, in multi-component reactions up to 11 different reactants form a single reaction product and in a telescopic synthesis one reactant goes through multiple transformations without isolation of intermediates.

Like malonic acid and its ester derivatives, and other 1,3-dicarbonyl compounds, Meldrum's acid can and serve as a reactant for a variety of nucleophilic reactions.

The reactant mixture is rendered to intense homogenization, to as much as 35,000 psi, so that various constituents do not separate out during storage or distribution.

The binding energy of the enzyme-substrate complex cannot be considered as an external energy which is necessary for the substrate activation. The enzyme of high energy content may firstly transfer some specific energetic group X1 from catalytic site of the enzyme to the final place of the first bound reactant, then another group X2 from the second bound reactant (or from the second group of the single reactant) must be transferred to active site to finish substrate conversion to product and enzyme regeneration. We can present the whole enzymatic reaction as a two coupling reactions: It may be seen from reaction () that the group X1 of the active enzyme appears in the product due to possibility of the exchange reaction inside enzyme to avoid both electrostatic inhibition and repulsion of atoms. So we represent the active enzyme as a powerful reactant of the enzymatic reaction.

Changing the solvent instead of the reactant can provide insight into changes in charge during the reaction. The Grunwald- Winstein Plot provides quantitative insight into these effects.

The white section denotes special hazard information. One example of a special hazard would be the capital letter W crossed out (pictured left), indicating it is water reactant.

Effectively, the postulate states that the structure of a transition state resembles that of the species nearest to it in free energy. This can be explained with reference to potential energy diagrams: Energy diagrams showing how to interpret Hammond's Postulate In case (a), which is an exothermic reaction, the energy of the transition state is closer in energy to that of the reactant than that of the intermediate or the product. Therefore, from the postulate, the structure of the transition state also more closely resembles that of the reactant. In case (b), the energy of the transition state is close to neither the reactant nor the product, making none of them a good structural model for the transition state.

Effectively, the postulate states that the structure of a transition state resembles that of the species nearest to it in free energy. This can be explained with reference to potential energy diagrams: right In case (a), which is an exothermic reaction, the energy of the transition state is closer in energy to that of the reactant than that of the intermediate or the product. Therefore, from the postulate, the structure of the transition state also more closely resembles that of the reactant. In case (b), the energy of the transition state is close to neither the reactant nor the product, making none of them a good structural model for the transition state.

Enantioconvergent synthesis is the synthesis of one enantiomer from a racemic precursor molecule utilizing both enantiomers. Thus, the two enantiomers of the reactant produce a single enantiomer of product.

In complexation catalysis, the term dynamic binding refers to any stabilizing interaction that is stronger at the transition state level than in the reactant-catalyst complex. Being directly related to transition state stabilization, dynamic binding is the very hearth of complexation catalysis. It was defined by A.J. Kirby in 1996 as opposed to the passive binding, i.e. the whole of interactions that are equally strong at the reactant and the transition state level.

This method is most useful when there are only two reactants. One reactant (A) is chosen, and the balanced chemical equation is used to determine the amount of the other reactant (B) necessary to react with A. If the amount of B actually present exceeds the amount required, then B is in excess and A is the limiting reagent. If the amount of B present is less than required, then B is the limiting reagent.

This is the case with the conversion of diamond to lower energy graphite at atmospheric pressure, in such a reaction diamond is considered metastable and will not be observed converting into graphite. If the products are higher in chemical energy than the reactants then the reaction will require energy to be performed and is therefore an endergonic reaction. Additionally if the product is less stable than a reactant, then Leffler's assumption holds that the transition state will more closely resemble the product than the reactant. Sometimes the product will differ significantly enough from the reactant that it is easily purified following the reaction such as when a product is insoluble and precipitates out of solution while the reactants remained dissolved.

The concentration polarization is the result of practical limitations on mass transport within the cell and represents the voltage loss due to spatial variations in reactant concentration at the chemically active sites. This situation can be caused when the reactants are consumed by the electrochemical reaction faster than they can diffuse into the porous electrode, and can also be caused by variation in bulk flow composition. The latter is due to the fact that the consumption of reacting species in the reactant flows causes a drop in reactant concentration as it travels along the cell, which causes a drop in the local potential near the tail end of the cell. The concentration polarization occurs in both the anode and cathode.

Isotopic labeling (or isotopic labelling) is a technique used to track the passage of an isotope (an atom with a detectable variation in neutron count) through a reaction, metabolic pathway, or cell. The reactant is 'labeled' by replacing specific atoms by their isotope. The reactant is then allowed to undergo the reaction. The position of the isotopes in the products is measured to determine the sequence the isotopic atom followed in the reaction or the cell's metabolic pathway.

In order to return to a lower energy state, either the hydroxyl group leaves, or the chloride leaves. In solution both processes happen. A small percentage of the intermediate loses the chloride to become the product (2,4-dinitrophenol), while the rest return to the reactant. Since 2,4-dinitrophenol is in a lower energy state it will not return to form the reactant, so after some time has passed, the reaction reaches chemical equilibrium that favors the 2,4-dinitrophenol.

Vincenzo Balzani, Giacomo Bergamini, Paola Ceroni, Light: A Very Peculiar Reactant and Product. In: Angewandte Chemie International Edition 54, Issue 39, (2015), 11320–11337, . Some applications use the heat generated by the filament.

The probe is essentially maintenance-free. Using modern, high precision stepper motor driven burettes, automated thermometric titrations are usually complete in a few minutes, making the technique an ideal choice where high laboratory productivity is required. ;Spectroscopy: Spectroscopy can be used to measure the absorption of light by the solution during the titration, if the spectrum of the reactant, titrant or product is known. The relative amounts of the product and reactant can be used to determine the equivalence point.

Telechelic oligomer approach applies the usual polymerization manner except that one includes a monofunctional reactant to stop reaction at the oligomer stage, generally in the 50-3000 molecular weight. The monofunctional reactant not only limits polymerization but end-caps the oligomer with functional groups capable of subsequent reaction to achieve curing of the oligomer. Functional groups like alkyne, norbornene, maleimide, nitrite, and cyanate have been used for this purpose. Maleimide and norbornene end-capped oligomers can be cured by heating.

The reactant polymer gel is then chopped, dried and ground to its final granule size. Any treatments to enhance performance characteristics of the SAP are usually accomplished after the final granule size is created.

Two transport mechanisms are fundamental for nanoelectrochemistry: electron transfer and mass transport. The formulation of theoretical models allows to understand the role of the different species involved in the electrochemical reactions. The electron transfer between the reactant and the nanoelectrode can be explained by the combination of various theories based on the Marcus theory. Mass transport, that is the diffusion of the reactant molecules from the electrolyte bulk to the nanoelectrode, is influenced by the formation of a double electric layer at the electrode/electrolyte interface.

The Spinco Division Model 260 Reaction Kinetics System measured the precise rate constants of molecular reactions. The experimental determination of reaction rates involves measuring how the concentrations of reactants or products change over time. For example, the concentration of a reactant can be measured by spectrophotometry at a wavelength where no other reactant or product in the system absorbs light. For reactions which take at least several minutes, it is possible to start the observations after the reactants have been mixed at the temperature of interest.

Hammond postulate is another tool which assists in drawing the energy of a transition state relative to a reactant, an intermediate or a product. It states that the transition state resembles the reactant, intermediate or product that it is closest in energy to, as long the energy difference between the transition state and the adjacent structure is not too large. This postulate helps to accurately predict the shape of a reaction coordinate diagram and also gives an insight into the molecular structure at the transition state.

' When a polysilicon deposition process becomes mass-transport- limited, the reaction rate becomes dependent primarily on reactant concentration, reactor geometry, and gas flow. When the rate at which polysilicon deposition occurs is slower than the rate at which unreacted silane arrives, then it is said to be surface-reaction-limited. A deposition process that is surface-reaction-limited is primarily dependent on reactant concentration and reaction temperature. Deposition processes must be surface- reaction-limited because they result in excellent thickness uniformity and step coverage.

This parameter is used to calculate the mass of co-reactant (hardener) to use when curing epoxy resins. Epoxies are typically cured with stoichiometric or near-stoichiometric quantities of hardener to achieve the best physical properties.

Energy diagrams of SN1 reactions Hammond's postulate can be used to examine the structure of the transition states of a SN1 reaction. In particular, the dissociation of the leaving group is the first transition state in a SN1 reaction. The stabilities of the carbocations formed by this dissociation are known to follow the trend tertiary > secondary > primary > methyl. Therefore, since the tertiary carbocation is relatively stable and therefore close in energy to the R-X reactant, then the tertiary transition state will have a structure that is fairly similar to the R-X reactant.

The proposed two- step mechanism has a rate-limiting first step whose molecularity corresponds to the overall order of 3: :2 NO + H2 -> N2 + H2O2 (slow) :H2O2 + H2 -> 2H2O (fast) On the other hand, the molecularity of this reaction is undefined, because it involves a mechanism of more than one step. However, we can consider the molecularity of the individual elementary reactions that make up this mechanism: the first step is termolecular because it involves three reactant molecules, while the second step is bimolecular because it involves two reactant molecules.

A more accurate yield is measured based on how much product was actually produced versus how much could be produced. The ratio of the theoretical yield and the actual yield results in a percent yield. When more than one reactant participates in a reaction, the yield is usually calculated based on the amount of the limiting reactant, whose amount is less than stoichiometrically equivalent (or just equivalent) to the amounts of all other reactants present. Other reagents present in amounts greater than required to react with all the limiting reagent present are considered excess.

In chemistry, the selection rule (also known as the transition rule) formally restrict certain reactions, known as spin-forbidden reactions, from occurring due to a required change between two differing quantum states. When a reactant exists in one spin state and the product exists in a different spin state, the corresponding reaction will have an increased activation energy when compared to a similar reaction in which the spin states of the reactant and product are isomorphic. As a result of this increased activation energy, a decreased rate of reaction is observed.

Conversion can be separated into instantaneous conversion and overall conversion. For continuous processes the two are the same, for batch and semi- batch there are important differences. Furthermore, for multiple reactants, conversion can be defined overall or per reactant.

Eliel, E., "Stereochemistry of Carbon Compound", McGraw-Hill, 1962 pp 434-436 In contrast, stereoselectivity is the property of a reactant mixture where a non-stereospecific mechanism allows for the formation of multiple products, but where one (or a subset) of the products is favored by factors, such as steric access, that are independent of the mechanism. A stereospecific mechanism specifies the stereochemical outcome of a given reactant, whereas a stereoselective reaction selects products from those made available by the same, non-specific mechanism acting on a given reactant. Given a single, stereoisomerically pure starting material, a stereospecific mechanism will give 100% of a particular stereoisomer (or no reaction), although loss of stereochemical integrity can easily occur through competing mechanisms with different stereochemical outcomes. A stereoselective process will normally give multiple products even if only one mechanism is operating on an isomerically pure starting material.

By DFT and TD-DFT methods one can obtain IR, Raman and UV spectra. Results of such calculations can be compared with experimental results. Fullerene is an unusual reactant in many organic reactions such as the Bingel reaction discovered in 1993.

The activation energy for a chemical reaction can be provided when one reactant molecule absorbs light of suitable wavelength and is promoted to an excited state. The study of reactions initiated by light is photochemistry, one prominent example being photosynthesis.

Oxidation of the alcohols gives majorly compound 5, but also compound 6. These are both ketones, but they have other stereochemistry. Compound 6 can be converted back in compound 5 with reactant c, thereby moving the equilibrium towards compound 5.

Thulium(III) bromide is used as a reagent for the complexation of lanthanide bromides with aluminium bromide, and as a reactant for preparing alkali metal thulium bromides. It is also used to create discharge lamps that are free of mercury.

The use of biocatalysis to obtain enantiopure compounds can be divided into two different methods: # Kinetic resolution of a racemic mixture # Biocatalyzed asymmetric synthesis In kinetic resolution of a racemic mixture, the presence of a chiral object (the enzyme) converts one of the stereoisomers of the reactant into its product at a greater reaction rate than for the other reactant stereoisomer. The stereochemical mixture has now been transformed into a mixture of two different compounds, making them separable by normal methodology. Scheme 1. Kinetic resolution Biocatalyzed kinetic resolution is utilized extensively in the purification of racemic mixtures of synthetic amino acids.

In chemistry, yield, also referred to as reaction yield, is a measure of the quantity of moles of a product formed in relation to the reactant consumed, obtained in a chemical reaction, usually expressed as a percentage. Yield is one of the primary factors that scientists must consider in organic and inorganic chemical synthesis processes. In chemical reaction engineering, "yield", "conversion" and "selectivity" are terms used to describe ratios of how much of a reactant was consumed (conversion), how much desired product was formed (yield) in relation to the undesired product (selectivity), represented as X, Y, and S.

In the absence of high temperatures, high pressures, metal catalysts or UV light, biotransformation plays the dominant role in environmental alkane degradation. The mechanisms and genetics of aerobic hydrocarbon degradation have been described extensively . The key feature of aerobic degradation is the role of dioxygen. Oxygen is not only a physiological requirement, but serves as a reactant in the hydroxylation of both aliphatic and aromatic hydrocarbons via monooxygenase and dioxygenase enzymes . Oxygen’s key role as a reactant during aerobic hydrocarbon degradation led to the belief for many years that n-alkanes and other hydrocarbons were recalcitrant under anoxic conditions.

Reaction rate tends to increase with concentration phenomenon explained by collision theory Collision theory states that when suitable particles of the reactant hit each other, only a certain amount of collisions result in a perceptible or notable change; these successful changes are called successful collisions. The successful collisions must have enough energy, also known as activation energy, at the moment of impact to break the pre-existing bonds and form all new bonds. This results in the products of the reaction. Increasing the concentration of the reactant brings about more collisions and hence more successful collisions.

It is important to note that the group H+, initially found on the enzyme, but not in water, appears in the product before the step of hydrolysis, therefore it may be considered as an additional group of the enzymatic reaction. Thus, the reaction () shows that the enzyme acts as a powerful reactant of the reaction. According to the proposed concept, the H transport from the enzyme promotes the first reactant conversion, breakdown of the first initial chemical bond (between groups P1 and P2). The step of hydrolysis leads to a breakdown of the second chemical bond and regeneration of the enzyme.

Primary condition is addition of reactant molecules at a very small rate to SWNT solution for a sufficient long time. This ensures reaction with only metallic SWNTs and with no semiconducting SWNTs as all the reactant molecules are taken up by the metallic SWNTs. Long time injection ensures that all metallic tubes are reacted. For example, one highly selective condition is: addition of 500 µL of 4-hydroxybenzene diazonium tetrafluoroborate solution in water (0.245 mM) at an injection rate of 20.83 µL/h into 5 mL of SWNT solution (1 wt % sodium dodecyl sulfate (SDS)) over 24 hrs.

In a conventional chemical rocket engine, the rocket carries both its fuel and oxidizer in its fuselage. The chemical reaction between the fuel and the oxidizer produces reactant products which are nominally gasses at the pressures and temperatures in the rocket's combustion chamber. The reaction is also highly energetic (exothermic) releasing tremendous energy in the form of heat; that is imparted to the reactant products in the combustion chamber giving this mass enormous internal energy which, when expanded through a nozzle is capable of producing very high exhaust velocities. The exhaust is directed rearward through the nozzle, thereby producing a thrust forward.

His chemical work included purine chemistry, the identification of caffeine, the discovery of the first coal tar dye (aniline blue), (Runge called aniline blue "Kyanol" (blue-oil)) coal tar products (and a large number of substances that derive from coal tar), paper chromatography, pyrrole, chinoline, phenol, thymol and atropine. Runge placed drops of reactant solutions on blotting paper and then added a drop of a second reactant solution on top of the first drop. The solutions would react as they spread through the blotting paper, often producing colored patterns. His results were published in two books, Farbenchemie.

The silicate wall of the pores is amorphous. Mesoporous silicates, such as MCM-41 and SBA-15 (the most common mesoporous silicates), are porous silicates with huge surface areas (normally ≥1000 m²/g), large pore sizes (2 nm ≤ size ≤ 20 nm) and ordered arrays of cylindrical mesopores with very regular pore morphology. The large surface areas of these solids increase the probability that a reactant molecule in solution will come into contact with the catalyst surface and react. The large pore size and ordered pore morphology allow one to be sure that the reactant molecules are small enough to diffuse into the pores.

The Zn(CN)2 reacts with the HCl to form the key HCN reactant and Zn(CN)2 that serves as the Lewis-acid catalyst in-situ. An example of the Zn(CN)2 method is the synthesis of mesitaldehyde from mesitylene.

Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbonylation also refers to oxidation of protein side chains.

Solid reactant compounds are channeled to the two pieces of metal being joined. Once in place, a catalyst is used to start the reaction. This catalyst can be a chemical or another heat source. The heat created melts the metals being joined.

The general reaction scheme is as follows: General Scheme for Buchner Reaction The reaction yields two possible carbonyl compounds (I and II) along with an epoxide (III). The ratio of the products is determined by the reactant used and the reaction conditions.

The diastereoselectivity of radical cyclizations is often high. In most all-carbon cases, selectivity can be rationalized according to Beckwith's guidelines, which invoke the reactant-like, exo transition state shown above.Beckwith, A.; Christopher, J.; Lawrence, T.; Serelis, A. Aust. J. Chem. 1983, 36, 545.

Solid reactant welding uses reactions between elements and compounds. Certain compounds when mixed create an exothermic chemical reaction, meaning they give off heat. A very common reaction uses thermite, a combination of a metal oxide (rust) and aluminum. This reaction produces heat over 4000 °F.

Unlike the soot example above, commercial PECVD relies on electromagnetic means (electric current, microwave excitation), rather than a chemical-reaction, to produce a plasma. Atomic layer deposition (ALD), and its sister technique molecular layer deposition (MLD), uses gaseous precursor to deposit conformal thin films one layer at a time. The process is split up into two half reactions, run in sequence and repeated for each layer, in order to ensure total layer saturation before beginning the next layer. Therefore, one reactant is deposited first, and then the second reactant is deposited, during which a chemical reaction occurs on the substrate, forming the desired composition.

Usually, the more complex the reactant molecules, the lower the steric factors. Nevertheless, some reactions exhibit steric factors greater than unity: the harpoon reactions, which involve atoms that exchange electrons, producing ions. The deviation from unity can have different causes: the molecules are not spherical, so different geometries are possible; not all the kinetic energy is delivered into the right spot; the presence of a solvent (when applied to solutions); and so on. When collision theory is applied to reactions in solution, the solvent cage has an effect on the reactant molecules, as several collisions can take place in a single encounter, which leads to predicted preexponential factors being too large.

Dolomitization is a geological process by which the carbonate mineral dolomite is formed when magnesium ions replace calcium ions in another carbonate mineral, calcite. It is common for this mineral alteration into dolomite to take place due to evaporation of water in the sabkha area. Dolomitization involves substantial amount of recrystallization. This process is described by the stoichiometric equation: 2 CaCO3(calcite) \+ Mg2+ ↔ CaMg(CO3)2(dolomite) \+ Ca2+ Dolomitization depends on specific conditions which include low Ca:Mg ratio in solution, reactant surface area, the mineralogy of the reactant, high temperatures which represents the thermodynamic stability of the system, and the presence of kinetic inhibitors such as sulfate.

The redox reaction that produces the electrical current happens in the synthetic pathway, where 13 enzymes, such as glucose 6-phosphate and phosphoglucomutase, act as catalysts (the substance that is both reactant and product). The fuel, maltodextrin, is divided from polymer to monomer and then oxidized into carbon dioxide and hydrogen ions during four reactions. The reactions involve the enzymatic catalysts, but since they act both as reactant and product, the amount of the enzymes does not decrease in the end so that they can keep facilitating the reaction. At the end of the reaction, One glucose unit and a certain amount of water can produce 24 electrons.

The limiting reagent (or limiting reactant or limiting agent) in a chemical reaction is a reactant that is totally consumed when the chemical reaction is completed. The amount of product formed is limited by this reagent, since the reaction cannot continue without it. If one or more other reagents are present in excess of the quantities required to react with the limiting reagent, they are described as excess reagents or excess reactants (xs). The limiting reagent must be identified in order to calculate the percentage yield of a reaction since the theoretical yield is defined as the amount of product obtained when the limiting reagent reacts completely.

Scheme of eudiometer Applications of a eudiometer include the analysis of gases and the determination of volume differences in chemical reactions. The eudiometer is filled with water, inverted so that its open end is facing the ground (while holding the open end so that no water escapes), and then submersed in a basin of water. A chemical reaction is taking place through which gas is created. One reactant is typically at the bottom of the eudiometer (which flows downward when the eudiometer is inverted) and the other reactant is suspended on the rim of the eudiometer, typically by means of a platinum or copper wire (due to their low reactivity).

Though not well known, many friends and people who knew him well acknowledge it was likely suicide, as the fire was fueled by a "petroleum reactant." Goddard was survived by his wife, Ethel, who was also injured in the fire. They had two sons: Kim and Mark.

The decarboxylation removes product quickly, and thus the reaction moves forward even though there would be much more reactant than product if the system were allowed to reach equilibrium by itself. The enzyme carboxyphosphoenolpyruvate phosphonomutase performs a similar reaction, converting P-carboxyphosphoenolpyruvate to phosphinopyruvate and carbon dioxide.

Mild conditions allow this reaction to take place while not affecting complex or reducible groups in the reactant-acid. The reaction requires the presence of a nucleophile (water). A metal catalyst is required. Usually Ag2O is chosen but other metals and even light effect the reaction.

Several reactions are required to obtain the gaseous reactants required for Fischer–Tropsch catalysis. First, reactant gases entering a Fischer–Tropsch reactor must be desulfurized. Otherwise, sulfur-containing impurities deactivate ("poison") the catalysts required for Fischer–Tropsch reactions. Several reactions are employed to adjust the H2:CO ratio.

Donation of lone pair electrons into the vacant p-orbital of singlet fluorenylidene. Singlet fluorenylidene reacts with olefins in a concerted fashion, maintaining the stereochemistry of the reactant olefin. Triplet quenchers such as butadiene solvents can be used to increase stereospecific yields. Halogenated solvents also stabilize the singlet state.

Warp plasma is highly unstable and can be easily detonated. Until recently, it was considered an undeliverable medium that could not be controlled. However, using a nanite- controlled trigger for reactant release now allows vessels to deliver a high- energy plasma warhead payload within a Mark IV torpedo casing.

The combustion of methane, a hydrocarbon. In complete combustion, the reactant burns in oxygen and produces a limited number of products. When a hydrocarbon burns in oxygen, the reaction will primarily yield carbon dioxide and water. When elements are burned, the products are primarily the most common oxides.

Inversely, reactions that form a positive charge on said carbon (i.g. Cytochrome-P450 oxidation of the double bond), are faster with MeAN as the reactant. As a result, in metabolism, MeAN conjugates less with glutathione (GSH) than AN, and is activated more easily. El Hadri, L., et al. (2005).

Another type of innovative neutron generator is the inertial electrostatic confinement fusion device. This neutron generator avoids using a solid target which will be sputter eroded causing metalization of insulating surfaces. Depletion of the reactant gas within the solid target is also avoided. Far greater operational lifetime is achieved.

Figure 1. A generic More O’Ferrall–Jencks plot. R, I(1), I(2) and P stand for reactant(s), intermediate(s) 1, intermediate(s) 2 and product(s) respectively. The thick arrows represent movement of the transition state (black dot) parallel and perpendicular to the diagonal (red line).

Performic acid is synthesized by the reaction of formic acid and hydrogen peroxide by the following equilibrium reaction: Synthesis of Performic acid Synthesis of pure performic acid has not been reported, but aqueous solutions up to about 48% can be formed by simply mixing equimolar amounts of concentrated aqueous reactant solutions. Using an excess of either reactant shifts the equilibrium towards the product side. The aqueous product solution can be distilled to increase the concentration of performic acid to about 90%. This reaction is reversible and can be used for large scale industrial production if accelerated with a catalyst; however, its temperature must be kept below 80–85 °C to avoid an explosion.

In situ infrared spectroscopy may be used to monitor the course of a reaction, provided a reagent or product shows distinctive absorbance in the IR spectral region. The rate of reactant consumption and/or product formation may be abstracted from the change of absorbance over time (by application of Beers' Law). Even when reactant and product spectra display some degree of overlap, modern instrumentation software is generally able to accurately deconvolute the relative contributions provided there is a dramatic change in the absolute absorbance of the peak of interest over time. In situ IR may be classified as an integral technique as the primary data collected are proportional to concentration vs. time.

In nucleophilic aliphatic substitution, sodium nitrite (NaNO2) replaces an alkyl halide. In the so-called Ter Meer reaction (1876) named after Edmund ter Meer, the reactant is a 1,1-halonitroalkane: :The ter Meer reaction The reaction mechanism is proposed in which in the first slow step a proton is abstracted from nitroalkane 1 to a carbanion 2 followed by protonation to an aci-nitro 3 and finally nucleophilic displacement of chlorine based on an experimentally observed hydrogen kinetic isotope effect of 3.3. When the same reactant is reacted with potassium hydroxide the reaction product is the 1,2-dinitro dimer.3-Hexene, 3,4-dinitro- D. E. Bisgrove, J. F. Brown, Jr., and L. B. Clapp.

Phosphorus triiodide is commonly used in the laboratory for the conversion of primary or secondary alcohols to alkyl iodides.B. S. Furnell et al., Vogel's Textbook of Practical Organic Chemistry, 5th edition, Longman/Wiley, New York, 1989. The alcohol is frequently used as the solvent, on top of being the reactant.

Reactions can take place between two solids. However, because of the relatively small diffusion rates in solids, the corresponding chemical reactions are very slow in comparison to liquid and gas phase reactions. They are accelerated by increasing the reaction temperature and finely dividing the reactant to increase the contacting surface area.

A highly exothermic reaction combusts magnesium in an oxidation–reduction reaction with carbon dioxide, producing a variety of carbon nanoparticles including graphene and fullerenes. The carbon dioxide reactant may be either solid (dry-ice) or gaseous. The products of this reaction are carbon and magnesium oxide. was issued for this process.

Electron transfer (ET) occurs when an electron relocates from an atom or molecule to another such chemical entity. ET is a mechanistic description of a redox reaction, wherein the oxidation state of reactant and product changes. Numerous biological processes involve ET reactions. These processes include oxygen binding, photosynthesis, respiration, and detoxification.

The number of electrons donated or accepted in a redox reaction can be predicted from the electron configuration of the reactant element. Elements try to reach the low-energy noble gas configuration, and therefore alkali metals and halogens will donate and accept one electron respectively. Noble gases themselves are chemically inactive.Wiberg, pp.

The oxidizer is the other reactant of the chemical reaction. In most cases, it is the ambient air, and in particular one of its components, oxygen (O2). By depriving a fire of air, it can be extinguished. For example, when covering the flame of a small candle with an empty glass, fire stops.

In the early 1890s, pyrite was also extracted, initially in small quantities. The expanding chemical industry used the pyrite as a reactant for the manufacture of sulphuric acid. By 1901 20,000 tonnes had been extracted. In 1903, pyrite mining was temporarily halted, because larger mineral deposits were superseding the smaller local suppliers.

15 °C – 150 °C. The range for a given instrument may be somewhat different. IMC is extremely sensitive – e.g. heat from slow chemical reactions in specimens weighing a few grams, taking place at reactant consumption rates of a few percent per year, can be detected and quantified in a matter of days.

Synthesis of dapoxetine Currently very few methods are used to synthesize (S)-dapoxetine. This novel approach consists of only six steps in which three main steps are shown above. The initial reactant is trans-cinnamyl alcohol which is commercial available. Sharpless asymmetric epoxidation and Mitsunobu reaction have been used to produce expected (S)-dapoxetine.

On the two-reactant one-step activation- energy asymptotics for steady, adiabatic, planar flames with Lewis numbers of unity. Combustion Theory and Modelling, 22(5), 913-920. it became popular in western community and since then it was widely used to explain more complicated problems in combustion.Buckmaster, J. D., & Ludford, G. S. S. (1982).

Unfortunately, because the leaving group is also an alcohol, the forward and reverse reactions will often occur at similar rates. Using a large excess of the reactant alcohol or removing the leaving group alcohol (e.g. via distillation) will drive the forward reaction towards completion, in accordance with Le Chatelier's principle.Wade 2010, pp. 1005–1009.

Green olives may be treated industrially with ferrous gluconate (0.4 wt. %) to change their color to black. Gluconate, an edible oxidation product of glucose, is used as non-toxic reactant to maintain Fe2+ in solution. When in contact with polyphenols, the ferrous ions form a black complex, giving the final color of the treated olives.

AL-LAD, also known as 6-allyl-6-nor-LSD, is a psychedelic drug and an analog of lysergic acid diethylamide (LSD). It is described by Alexander Shulgin in the book TiHKAL (Tryptamines i Have Known And Loved). It is synthesized starting from nor-LSD as a precursor, using allyl bromide as a reactant.

Several commercial samples of MDMB-CHMICA were found to exclusively contain the (S)-enantiomer based on vibrational and electronic circular dichroism spectroscopy and X-ray crystallography. An (S)-configuration for the tert- leucinate group is unsurprising since MDMB-CHMICA is likely synthesized from the abundant and inexpensive "L" form of the appropriate tert-leucinate reactant.

MCH neurons depolarize in response to high glucose concentrations. This mechanism seems to be related to glucose being used as a reactant to form ATP, which also causes MCH neurons to depolarize. The neurotransmitter, glutamate, also causes MCH neurons to depolarize, while another neurotransmitter, GABA, causes MCH neurons to hyperpolarize. Orexin also depolarizes MCH neurons.

The anode can be particularly problematic, as the oxidation of the hydrogen produces steam, which further dilutes the fuel stream as it travels along the length of the cell. This polarization can be mitigated by reducing the reactant utilization fraction or increasing the electrode porosity, but these approaches each have significant design trade-offs.

Synthetic resins are of several classes. Some are manufactured by esterification of organic compounds. Some are thermosetting plastics in which the term "resin" is loosely applied to the reactant or product, or both. "Resin" may be applied to one of two monomers in a copolymer, the other being called a "hardener", as in epoxy resins.

By the time the ride closed, many of the effects were no longer active or had been covered up. Blacklight reactant paint lined the walls, mostly in the form of handprints or outlines of scenes. These gave a 3-D appearance when the rider wore special glasses purchased at the beginning of the queue.

Yarwil AS is a joint venture between Yara International and Wilhelmsen Maritime Services. The Norwegian registered company provides systems for reduction of NOx emissions from ship engines. The technology is based on the Selective Catalytic Reduction (SCR) method using Urea as a reactant. This method can reduce NOx emissions from ships by as much as 95%.

These are the solid reactants from which it is proposed to prepare a solid crystalline compound. The selection of reactant chemicals depends on the reaction conditions and expected nature of the product. The reactants are dried thoroughly prior to weighing. As increase in surface area enhances the reaction rate, fine grained materials should be used if possible.

On July 29, 2011, Nacogdoches authorities told NASA that a piece of debris had been found in a lake. NASA identified the piece as a power reactant storage and distribution tank. All recovered non-human Columbia debris is stored in unused office space at the Vehicle Assembly Building, except for parts of the crew compartment, which are kept separate.

The following equation gives an overview over the Atherton-Todd reaction using the reactant dimethyl phosphite as an example: Atherton-Todd-Reaktion The reaction takes place after the addition of tetrachloromethane and a base. This base is usually a primary, secondary or tertiary amine. Instead of methyl groups other alkyl or benzyl groups may be present.

The Thorpe reaction is a chemical reaction described as a self- condensation of aliphatic nitriles catalyzed by base to form enamines. [8] The Thorpe–Ziegler reaction is the intramolecular modification with a dinitrile as a reactant and a cyclic ketone after acid hydrolysis. In the Guareschi-Thorpe condensation cyanoacetamide reacts with a 1,3-diketone to a 2-pyridone.

In heterogeneous catalysis, when a reactant molecule physisorbs to a catalyst, it is commonly said to be in a precursor state, an intermediate energy state before chemisorption, a more strongly bound adsorption. From the precursor state, a molecule can either undergo chemisorption, desorption, or migration across the surface. The nature of the precursor state can influence the reaction kinetics.

Flow hydrogenation has become a popular technique at the bench and increasingly the process scale. This technique involves continuously flowing a dilute stream of dissolved reactant over a fixed bed catalyst in the presence of hydrogen. Using established HPLC technology, this technique allows the application of pressures from atmospheric to . Elevated temperatures may also be used.

There are, however, a few problems with some syntheses. The Piloty-Robinson reaction competes with the formation of pyrazoline when the reactant is an aliphatic azine derived from a ketone. Also, under high temperatures and highly acidic solutions, azines derived from aldehydes are not stable. This prevents the formation of 2,5-disubstituted pyrroles (where R=H) using this method.

The word oxygen in the literature typically refers to the most common oxygen allotrope, elemental/diatomic oxygen (O2), as it is a common product or reactant of many biogeochemical redox reactions within the cycle. Processes within the oxygen cycle are considered to be biological or geological and are evaluated as either a source (O2 production) or sink (O2 consumption).

It was noted that the synthesis worked even on cloudy days. In the previous syntheses the fluorine gas reactant had been purified to remove hydrogen fluoride. Šmalc and Lutar found that if this step is skipped the reaction rate proceeds at four times the original rate. In 1965, it was also synthesized by reacting xenon gas with dioxygen difluoride.

The hydrophobic structure prevents the electrolyte from leaking into the reactant gas flow channels and ensures diffusion of the gases to the reaction site. The two layers are then pressed onto a conducting metal mesh, and sintering completes the process. Further variations on the alkaline fuel cell include the metal hydride fuel cell and the direct borohydride fuel cell.

Making an amide is one of the processes which require ammonia as a reactant. There are other processes of preparing an amide such as from acid anhydrides and acyl chloride. Carboxylic acids react with ammonium carbonate, to convert the carboxylic acids to ammonium salts. For example, acetic acid reacts with ammonium carbonate to produce ammonium acetate.

Structure of dicyanamide Dicyanamide, also known as dicyanamine, is an anion having the formula . It contains two cyanide groups bound to a central nitrogen anion. The chemical is formed by decomposition of 2-cyanoguanidine. It is used extensively as a counterion of organic and inorganic salts, and also as a reactant for the synthesis of various covalent organic structures.

Environmental Toxicology & Chemistry 20: 2717-2724. Similar observations have been reported for the herbicides trifluralin and atrazine. Alachlor is often used in high school chemistry classrooms as a reactant in demonstrations such as the combustion of magnesium. Alachlor can be used as a substitution for methane gas in such an experiment when gas is not available.

A study by DelDuca et al. used hydrogen produced by the fermentation of glucose by Clostridium butyricum as the reactant at the anode of a hydrogen and air fuel cell. Though the cell functioned, it was unreliable owing to the unstable nature of hydrogen production by the micro- organisms.DelDuca, M. G., Friscoe, J. M. and Zurilla, R. W. (1963).

As reactant concentration increases, the frequency of collision increases. The rate of gaseous reactions increases with pressure, which is, in fact, equivalent to an increase in concentration of the gas. The reaction rate increases in the direction where there are fewer moles of gas and decreases in the reverse direction. For condensed-phase reactions, the pressure dependence is weak.

The PUREX process was invented by Herbert H. Anderson and Larned B. Asprey at the Metallurgical Laboratory at the University of Chicago, as part of the Manhattan Project under Glenn T. Seaborg; their patent "Solvent Extraction Process for Plutonium" filed in 1947, mentions tributyl phosphate as the major reactant which accomplishes the bulk of the chemical extraction.

The Benesi–Hildebrand method is a mathematical approach used in physical chemistry for the determination of the equilibrium constant K and stoichiometry of non-bonding interactions. This method has been typically applied to reaction equilibria that form one-to-one complexes, such as charge- transfer complexes and host–guest molecular complexation. :{H} + G <=> HG The theoretical foundation of this method is the assumption that when either one of the reactants is present in excess amounts over the other reactant, the characteristic electronic absorption spectra of the other reactant are transparent in the collective absorption/emission range of the reaction system. Therefore, by measuring the absorption spectra of the reaction before and after the formation of the product and its equilibrium, the association constant of the reaction can be determined.

DNA damage by 4NQO is a potent model. 4NQO induces DNA lesions usually corrected by nucleotide excision repair. 4NQO’s four electron reduction product, 4-hydroxyaminoquinoline 1-oxide (4HAQO), is believed to be a carcinogenic metabolite of 4NQO. When 4NQO is metabolized to its electrophilic reactant, selyl-4HAQO, it reacts with DNA to form stable quinolone monoadducts considered responsible for its mutagenicity and genotoxicity.

4-Imidazolone arise from the condensation of arginine residues and 3-deoxyglucosone (R = CH2CH(OH)CH(OH)CH2OH). 3DG is made naturally via the Maillard reaction. It forms after glucose reacts with primary amino groups of lysine or arginine found in proteins. Because of the increased concentration of the reactant glucose, more 3DG forms with excessive blood sugar levels, as in uncontrolled diabetes.

The heating programme to be used depends very much on the form and reactivity of the reactants. In the control of either temperature or atmosphere, nature of the reactant chemicals are considered in detail. A good furnace is used for heat treatment. Pelleting of samples is preferred prior to heating, since it increases the area of contact between the grains.

Apart from its use as a reactant, has a variety of smaller applications. It is used as a shielding gas in welding methods such as atomic hydrogen welding. H2 is used as the rotor coolant in electrical generators at power stations, because it has the highest thermal conductivity of any gas. Liquid H2 is used in cryogenic research, including superconductivity studies.

The most common use of monopropellants is in low-impulse monopropellant rocket motors, such as reaction control thrusters, the usual propellant being hydrazine , p. 230 which is generally decomposed by exposure to an iridium, pp. 307—309 catalyst bed (the hydrazine is pre-heated to keep the reactant liquid). This decomposition produces the desired jet of hot gas and thus thrust.

A reaction that illustrates an enzyme cleaving a specific bond of the reactant in order to create two productsBond specificity, unlike group specificity, recognizes particular chemical bond types. This differs from group specificity, as it is not reliant on the presence of particular functional groups in order to catalyze a particular reaction, but rather a certain bond type (for example, a peptide bond).

An active-filter tuned oscillator is an active electronic circuit designed to produce a periodic signal. It consists of a bandpass filter and an active amplifier, such as an OP-AMP or a BJT. The oscillator is commonly tuned to a specific frequency by varying the reactant of the feedback path within the circuit. An example is the Colpitts oscillator.

After Schiff base formation, the fourth hydroxyl group on the fructose backbone is then deprotonated by an aspartate residue (aspartate 33), which results in an aldol cleavage. Schiff base hydrolysis yields two 3-carbon products. Depending on the reactant, F1P or FBP, the products are DHAP and glyceraldehyde or glyceraldehyde 3-phosphate, respectively. The ΔG°’ of this reaction is +23.9 kJ/mol.

Methylamine is prepared commercially by the reaction of ammonia with methanol in the presence of an aluminosilicate catalyst. Dimethylamine and trimethylamine are co-produced; the reaction kinetics and reactant ratios determine the ratio of the three products. The product most favored by the reaction kinetics is trimethylamine. :CH3OH + NH3 → CH3NH2 \+ H2O In this way, an estimated 115,000 tons were produced in 2005.

Consider the nuclear fission of 236U into 92Kr, 141Ba, and three neutrons. :236U → 92Kr + 141Ba + 3 n The mass number of the reactant, 236U, is 236. Because the actual mass is , its mass excess is +. Calculated in the same manner, the mass excess for the products, 92Kr, 141Ba, and three neutrons, are , and , respectively, for a total mass excess of .

For these structures to be utilized as nanofluidic devices, the interconnection between nano-channels and microfluidic systems becomes an important issue. There exist several ways to coat the inner surface with specific charges. Diffusion- limited patterning can be utilized because a bulk solution only penetrate the entrance of a nanochannel within a certain distance. Because the diffusion speed is different for each reactant.

The Chrysler Natrium is a hybrid fuel cell-type hydrogen vehicle based on the Chrysler Town and Country. It was showcased by Chrysler in 2001. The Natrium is powered by a battery pack and a fuel cell using hydrogen produced by a sodium borohydride reformer inside the car. Because the reactant (sodium borohydride, NaBH4) contains no carbon, the vehicle produces no carbon dioxide.

The reaction rate varies depending upon what substances are reacting. Acid/base reactions, the formation of salts, and ion exchange are usually fast reactions. When covalent bond formation takes place between the molecules and when large molecules are formed, the reactions tend to be slower. The nature and strength of bonds in reactant molecules greatly influence the rate of their transformation into products.

Alpha-1-acid glycoprotein 1 is a protein that in humans is encoded by the ORM1 gene. This gene encodes a key acute phase plasma protein. Because of its increase due to acute inflammation, this protein is classified as an acute- phase reactant. The specific function of this protein has not yet been determined; however, it may be involved in aspects of immunosuppression.

Titration involves the addition of a reactant to a solution being analyzed until some equivalence point is reached. Often the amount of material in the solution being analyzed may be determined. Most familiar to those who have taken chemistry during secondary education is the acid-base titration involving a color changing indicator. There are many other types of titrations, for example potentiometric titrations.

It is a negative acute-phase reactant in sepsis and endotoxemia, promotes wound healing, and is neuroprotective in Alzheimer's disease. Decreased fetuin-A is a predictor of increased disease activity in obstructive lung disease, Crohn's disease, and ulcerative colitis. Differential effects on different toll like receptors in different tissues and organ systems may explain these paradoxical effects in different systems.

A collision between reactant molecules may or may not result in a successful reaction. The outcome depends on factors such as the relative kinetic energy, relative orientation and internal energy of the molecules. Even if the collision partners form an activated complex they are not bound to go on and form products, and instead the complex may fall apart back to the reactants.

Transport time can be substituted for T exposure to determine if a reaction can realistically occur depending on during how much of the transport time the reactant will be exposed to the correct conditions to react. A Damkohler number greater than 1 signifies that the reaction has time to react completely, whereas the opposite is true for a Damkohler number less than 1.

However, as shown, the application of surface binding dynamics in the form of a square wave at varying frequency and fixed oscillation amplitude but varying endpoints exhibits the full range of possible reactant selectivity. In the range of 1-10 Hertz, there exists a small island of parameters for which product C is highly selective; this condition is only accessible via dynamics.

Crude acetone is hydrogenated in the liquid phase over Raney nickel or a mixture of copper and chromium oxide to give isopropyl alcohol. This process is useful, when it is coupled with excess acetone production. Mitsui & Co. developed additional step(s) to hydrogenating the acetone product and dehydrating the isopropanol product to propene, which is recycled as a starting reactant.

The basic ideas behind transition state theory are as follows: #Rates of reaction can be studied by examining activated complexes near the saddle point of a potential energy surface. The details of how these complexes are formed are not important. The saddle point itself is called the transition state. #The activated complexes are in a special equilibrium (quasi- equilibrium) with the reactant molecules.

Although, a reaction coordinate diagram is essentially derived from a potential energy surface, it is not always feasible to draw one from a PES. A chemist draws a reaction coordinate diagram for a reaction based on the knowledge of free energy or enthalpy change associated with the transformation which helps him to place the reactant and product into perspective and whether any intermediate is formed or not. One guideline for drawing diagrams for complex reactions is the principle of least motion which says that a favored reaction proceeding from a reactant to an intermediate or from one intermediate to another or product is one which has the least change in nuclear position or electronic configuration. Thus, it can be said that the reactions involving dramatic changes in position of nuclei actually occur through a series of simple chemical reactions.

The following scheme describes the interconversion between an aldose and a ketose, where R is any organic residue. 700px The equilibrium or the reactant to product ratio depends on concentration, solvent, pH and temperature. At equilibrium the aldose and ketose form a mixture which in the case of the glyceraldehyde and dihydroxyacetone is also called glycerose. A related reaction is the alpha-ketol rearrangement.

Historically, pyrotechnic or explosive applications for traditional thermites have been limited due to their relatively slow energy release rates. Because nanothermites are created from reactant particles with proximities approaching the atomic scale, energy release rates are far greater. MICs or Super-thermites are generally developed for military use, propellants, explosives, incendiary devices, and pyrotechnics. Research into military applications of nano-sized materials began in the early 1990s.

Solution-based polymerization is commonly used today for SAP manufacture of co-polymers, particularly those with the toxic acrylamide monomer. This process is efficient and generally has a lower capital cost base. The solution process uses a water-based monomer solution to produce a mass of reactant polymerized gel. The polymerization's own exothermic reaction energy is used to drive much of the process, helping reduce manufacturing cost.

In this way, the entire reaction can keep going and no self-stopped. Notice that, for pure water electrolysis in nanogap cells, the net OH− ion accumulation near the anode not only increases the local reactant concentration, but also decreases the overpotential requirement (as in the Frumkin effect). According to Butler–Volmer equation, such ions accumulation can increase the electrolysis current, a.k.a., water splitting throughput and efficiency.

As a result, many reactions are incomplete and the reactants are not completely converted to products. If a reverse reaction occurs, the final state contains both reactants and products in a state of chemical equilibrium. Two or more reactions may occur simultaneously, so that some reactant is converted to undesired side products. Losses occur in the separation and purification of the desired product from the reaction mixture.

This is often seen in redox titrations, for instance, when the different oxidation states of the product and reactant produce different colors. ;Precipitation: If the reaction forms a solid, then a precipitate will form during the titration. A classic example is the reaction between Ag+ and Cl− to form the very insoluble salt AgCl. Surprisingly, this usually makes it difficult to determine the endpoint precisely.

The reaction is also a syn addition, and the configuration in the dipolarophile is preserved. The 1-pyrazoline is unstable and isomerizes to the 2-pyrazoline due to favorable conjugation with the ester group. With phenyldiazomethane as the reactant the regioselectivity is reversed and the reaction is extended even further by simple air organic oxidation of the 2-pyrazoline to the pyrazole. Diazoalkane 1,3-dipolar cycloaddition.

As a class of addition reaction, cycloadditions permit carbon–carbon bond formation without the use of a nucleophile or electrophile. Cycloadditions can be described using two systems of notation. An older but still common notation is based on the size of linear arrangements of atoms in the reactants. It uses parentheses: (i + j + ...) where the variables are the numbers of linear atoms in each reactant.

After reactant preparation, synthesis is initiated by point-heating of a small part (usually the top) of the sample. Once started, a wave of exothermic reaction sweeps through the remaining material. SHS has also been conducted with thin films, liquids, gases, powder–liquid systems, gas suspensions, layered systems, gas-gas systems, and others. Reactions have been conducted in a vacuum and under both inert or reactive gases.

Back-tracking has been found to be inefficient as even a five-step synthesis amounts to 1019 possible pathways. One can specify a molecule in several ways, including searching by Beilstein Registry Number, CAS registry number, chemical name, SMILES structure, or by drawing the molecule diagram itself. It supports optimization of reactions by cost. One can scale node sizes by molecular weight, product occurrence, and reactant occurrence.

Rate constant can be calculated for elementary reactions by molecular dynamics simulations. One possible approach is to calculate the mean residence time of the molecule in the reactant state. Although this is feasible for small systems with short residence times, this approach is not widely applicable as reactions are often rare events on molecular scale. One simple approach to overcome this problem is Divided Saddle Theory.

Carbon dioxide, a key reactant in photosynthesis, is present in the atmosphere at a concentration of about 400 ppm. Most plants require the stomata to be open during daytime. The air spaces in the leaf are saturated with water vapour, which exits the leaf through the stomata in a process known as transpiration. Therefore, plants cannot gain carbon dioxide without simultaneously losing water vapour.

This discovery overturned Lavoisier's definition of acids as compounds of oxygen. Davy was a popular lecturer and able experimenter. Joseph Louis Gay-Lussac, who stated that the ratio between the volumes of the reactant gases and the products can be expressed in simple whole numbers. French chemist Joseph Louis Gay-Lussac shared the interest of Lavoisier and others in the quantitative study of the properties of gases.

Conductometric titration is a type of titration in which the electrolytic conductivity of the reaction mixture is continuously monitored as one reactant is added. The equivalence point is the point at which the conductivity undergoes a sudden change. Marked increase or decrease in conductance are associated with the changing concentrations of the two most highly conducting ions—the hydrogen and hydroxyl ions.Katz et al.

A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae, wherein the reactant entities are given on the left-hand side and the product entities on the right-hand side. The coefficients next to the symbols and formulae of entities are the absolute values of the stoichiometric numbers. The first chemical equation was diagrammed by Jean Beguin in 1615.

B and C from the above equations usually represent different compounds. However, they could also just be different positions in the same molecule. A side reaction is also referred to as competing reaction when different compounds (B, C) compete for another reactant (A). If the side reaction occurs about as often as the main reaction, it is spoken of parallel reactions (especially in the kinetics, see below).

Photochemical immersion well reactor (750 mL) with a mercury-vapor lamp Photochemical reactions require a light source that emits wavelengths corresponding to an electronic transition in the reactant. In the early experiments (and in everyday life), sunlight was the light source, although it is polychromatic. Mercury-vapor lamps are more common in the laboratory. Low pressure mercury vapor lamps mainly emit at 254 nm.

If the reactants have a distribution of velocities, e.g. a thermal distribution, then it is useful to perform an average over the distributions of the product of cross section and velocity. This average is called the 'reactivity', denoted <σv>. The reaction rate (fusions per volume per time) is <σv> times the product of the reactant number densities: :f = n_1 n_2 \langle \sigma v \rangle.

The overall rate constant for the SRL cleavage reaction is second order (k2/K1/2 of 108M-1s-1). This means the reaction rate is directly proportional to the concentrations of the reactant squared. The rate does not appear to be dependent on physical steps, i.e. the two molecules being able to locate each other in solution is not a factor in how quickly they react.

Metallurgical coal or coking coal is a grade of coal that can be used to produce good-quality coke. Coke is an essential fuel and reactant in the blast furnace process for primary steelmaking. The demand for metallurgical coal is highly coupled to the demand for steel. Primary steelmaking companies often have a division that produces coal for coking, to ensure a stable and low-cost supply.

In case of multiple carbonyl types in one molecule, one can expect the most electrophilic carbonyl carbon to react first. Acyl chlorides and carboxylic anhydrides react fastest, followed by aldehydes and ketones. Esters react much more slowly and amides are almost completely unreactive due to resonance of the amide nitrogen towards the carbonyl group. This reactivity difference allows chemoselectivity when a reactant contains multiple carbonyl groups.

The Barton–McCombie deoxygenation is an organic reaction in which a hydroxy functional group in an organic compound is replaced by a hydrogen to give an alkyl group. It is named after British chemists Sir Derek Harold Richard Barton (1918–1998) and Stuart W. McCombie. The Barton-McCombie deoxygenation This deoxygenation reaction is a radical substitution. In the related Barton decarboxylation the reactant is a carboxylic acid.

Thorium(IV) Chloride can be produced in a variety of ways but the most common starting reactant is either thorium dioxide or Thorium (IV) orthosilicate. One way thorium(IV) chloride is synthesized is through a carbothermic reaction. The carbothermic reaction require very high temperature ranging from 700 °C to 2600 °C. What necessitates these extreme environments are thorium dioxides melting temperature of 3,390 °C.

A partly alternative synthesis can occur when the catalysts TRI1 and TRI13, TRI7 are used in opposite order. Then the addition of the hydroxyl groups at C7 and C8 controlled by TRI1 are happening with calonectrin as reactant. In this reaction 7,8-dihydroxycalonectrin is formed. It further reacts spontaneously to 3,15-acetyl-deoxynivalenol via elimination of a hydrogen and formation of a keto-group at C8.

The simplest chain-of-state method is the linear synchronous transit (LST) method. It operates by taking interpolated points between the reactant and product geometries and choosing the one with the highest energy for subsequent refinement via a local search. The quadratic synchronous transit (QST) method extends LST by allowing a parabolic reaction path, with optimization of the highest energy point orthogonally to the parabola.

When the enyne moiety is incorporated into a 10-membered hydrocarbon ring (e.g. cyclodeca-3-ene-1,5-diyne in scheme 2) the reaction, taking advantage of increased ring strain in the reactant, is possible at the much lower temperature of 37 °C. Scheme 2. Bergman reaction of cyclodeca-3-ene-1,5-diyne Naturally occurring compounds such as calicheamicin contain the same 10-membered ring and are found to be cytotoxic.

Another difference is that the barrelene reaction requires the triplet excited state while the Mariano and Pratt acyclic dienes used the excited singlet. Thus acetone is used in the barrelene reaction; acetone captures the light and then delivers triplet excitation to the barrelene reactant. In the final step of the rearrangement there is a spin- flip, termed intersystem-crossing (ISC) to provide paired electrons and a new sigma bond. Equation 3.

In economics and philosophy, scholars have applied game theory to help in the understanding of good or proper behavior. Game-theoretic arguments of this type can be found as far back as Plato. An alternative version of game theory, called chemical game theory, represents the player's choices as metaphorical chemical reactant molecules called “knowlecules”. Chemical game theory then calculates the outcomes as equilibrium solutions to a system of chemical reactions.

The simplest example of autocatalysis is a reaction of type A + B → 2 B, in one or in several steps. The overall reaction is just A → B, so that B is a product. But since B is also a reactant, it may be present in the rate equation and affect the reaction rate. As the reaction proceeds, the concentration of B increases and can accelerate the reaction as a catalyst.

The photochemical equivalence law applies to the part of a light-induced reaction that is referred to as the primary process (i.e. absorption or fluorescence). In most photochemical reactions the primary process is usually followed by so-called secondary photochemical processes that are normal interactions between reactants not requiring absorption of light. As a result, such reactions do not appear to obey the one quantum–one molecule reactant relationship.

The glyoxylate cycle is a variant of the citric acid cycle. It is an anabolic pathway occurring in plants and bacteria utilizing the enzymes isocitrate lyase and malate synthase. Some intermediate steps of the cycle are slightly different from the citric acid cycle; nevertheless oxaloacetate has the same function in both processes. This means that oxaloacetate in this cycle also acts as the primary reactant and final product.

Some approaches use a large zinc–air battery to maintain charge on a high discharge–rate battery used for peak loads during acceleration. Zinc granules serve as the reactant. Vehicles recharge via exchanging used electrolyte and depleted zinc for fresh reactants at a service station. The term zinc–air fuel cell usually refers to a zinc–air battery in which zinc metal is added and zinc oxide is removed continuously.

CAD protein is regulated by various molecules in order to increase or stop enzymatic activity. Uridine-5′-triphosphate (UTP) is an end product that allosterically inhibits the CPS II step through negative feedback. Additionally, UMP acts as an allosteric inhibitor to the CPS II reaction. On the other hand, this step is activated by 5-phosphoribosyl-α-pyrophosphate (PRPP), which is also a reactant for purine and pyrimidine synthesis.

Typical dispersities vary based on the mechanism of polymerization and can be affected by a variety of reaction conditions. In synthetic polymers, it can vary greatly due to reactant ratio, how close the polymerization went to completion, etc. For typical addition polymerization, Đ can range around 5 to 20. For typical step polymerization, most probable values of Đ are around 2 --Carothers' equation limits Đ to values of 2 and below.

While an isotope effect is the physical tendency for stable isotopes to distribute in a particular way, the isotopic fractionation is the measurable result of this tendency. The isotopic fractionation of a natural process can be calculated from measured isotope abundances. The calculated value is called a "fractionation factor," and allows the effect of different processes on isotope distributions to be mathematically compared. For example, imagine a chemical reaction Reactant → Product.

Thermochemistry is the study of the heat energy which is associated with chemical reactions and/or physical transformations. A reaction may release or absorb energy, and a phase change may do the same, such as in melting and boiling. Thermochemistry focuses on these energy changes, particularly on the system's energy exchange with its a surroundings. Thermochemistry is useful in predicting reactant and product quantities throughout the course of a given reaction.

Results regarding stable periodic solutions attempt to rule out "unusual" behaviour. If a given chemical reaction network admits a stable periodic solution, then some initial conditions will converge to an infinite cycle of oscillating reactant concentrations. For some parameter values it may even exhibit quasiperiodic or chaotic behaviour. While stable periodic solutions are unusual in real-world chemical reaction networks, well-known examples exist, such as the Belousov–Zhabotinsky reactions.

The level of procalcitonin in the blood stream of healthy individuals is below the limit of detection (0.01 µg/L) of clinical assays. The level of procalcitonin rises in a response to a pro-inflammatory stimulus, especially of bacterial origin. It is therefore often classed as an acute phase reactant. The induction period for procalcitonin ranges from 4–12 hours with a half-life spanning anywhere from 22–35 hours.

That is because more particles of the solid are exposed and can be hit by reactant molecules. Stirring can have a strong effect on the rate of reaction for heterogeneous reactions. Some reactions are limited by diffusion. All the factors that affect a reaction rate, except for concentration and reaction order, are taken into account in the reaction rate coefficient (the coefficient in the rate equation of the reaction).

Similarly, if we were to increase pressure by decreasing volume, the equilibrium shifts to the right, counteracting the pressure increase by shifting to the side with fewer moles of gas that exert less pressure. If the volume is increased because there are more moles of gas on the reactant side, this change is more significant in the denominator of the equilibrium constant expression, causing a shift in equilibrium.

Linear free-energy relationships (LFERs) exist when the relative influence of changing substituents on one reactant is similar to the effect on another reactant, and include linear Hammett plots, Swain–Scott plots, and Brønsted plots. LFERs are not always found to hold, and to see when one can expect them to, we examine the relationship between the free-energy differences for the two reactions under comparison. The extent to which the free energy of the new reaction is changed, via a change in substituent, is proportional to the extent to which the reference reaction was changed by the same substitution. A ratio of the free-energy differences is the reaction quotient or constant Q. ::: (ΔG'0 – ΔG'x) = Q(ΔG0 – ΔGx) The above equation may be rewritten as the difference (δ) in free-energy changes (ΔG): ::: δΔG = QδΔG Substituting the Gibbs free-energy equation (ΔG = ΔH – TΔS) into the equation above yields a form that makes clear the requirements for LFERs to hold.

Semibatch (semiflow) reactors operate much like batch reactors in that they take place in a single stirred tank with similar equipment. However, they are modified to allow reactant addition and/or product removal in time. A normal batch reactor is filled with reactants in a single stirred tank at time t=0 and the reaction proceeds. A semibatch reactor, however, allows partial filling of reactants with the flexibility of adding more as time progresses.

In terms of the graph of reaction coordinate versus energy, this is shown by the fact that the tertiary transition state is further to the left than the other transition states. In contrast, the energy of a methyl carbocation is very high, and therefore the structure of the transition state is more similar to the intermediate carbocation than to the R-X reactant. Accordingly, the methyl transition state is very far to the right.

Particularly exothermic fermentations may require the use of external heat exchangers. Nutrients may be continuously added to the fermenter, as in a fed-batch system, or may be charged into the reactor at the beginning of fermentation. The pH of the medium is measured and adjusted with small amounts of acid or base, depending upon the fermentation. For aerobic (and some anaerobic) fermentations, reactant gases (especially oxygen) must be added to the fermentation.

The suspension process is practiced by only a few companies because it requires a higher degree of production control and product engineering during the polymerization step. This process suspends the water-based reactant in a hydrocarbon-based solvent. The net result is that the suspension polymerization creates the primary polymer particle in the reactor rather than mechanically in post-reaction stages. Performance enhancements can also be made during, or just after, the reaction stage.

The dimerization of two cyclobutadienes can generate both the syn and anti ladderane products depending on the reaction conditions. The first step in forming the syn product involves the generation of 1,3-cyclobutadiene by treatment of cis-3,4-dichlorocyclobutene with sodium amalgam. The reactant passes through a metalated intermediate before forming 1,3-cyclobutadiene, which can then dimerize to form the syn-diene. Hydrogenation of the double bonds will form the saturated syn-[3]-ladderane.

In terms of the graph of reaction coordinate versus energy, this is shown by the fact that the tertiary transition state is further to the left than the other transition states. In contrast, the energy of a methyl carbocation is very high, and therefore the structure of the transition state is more similar to the intermediate carbocation than to the R-X reactant. Accordingly, the methyl transition state is very far to the right.

Methacrylonitrile is an acrylonitrile (AN) with an additional CH3 group on the second carbon. Polymerization does not require a catalyst and happens rapidly in the absence of a stabilizer. Because of its double bond, additional reactions are possible with biological molecules. The extra methyl group of MeAN lessens the electron-withdrawing effect caused by the nitrile so that reactions that form negative charge on the alpha carbon are faster with AN as the reactant.

In the beginning of the KEGG project, KEGG LIGAND consisted of three databases: KEGG COMPOUND for chemical compounds, KEGG REACTION for chemical reactions, and KEGG ENZYME for reactions in the enzyme nomenclature. Currently, there are additional databases: KEGG GLYCAN for glycans and two auxiliary reaction databases called RPAIR (reactant pair alignments) and RCLASS (reaction class). KEGG COMPOUND has also been expanded to contain various compounds such as xenobiotics, in addition to metabolites.

Poisoning often involves compounds that chemically bond to a catalyst's active sites. Poisoning decreases the number of active sites, and the average distance that a reactant molecule must diffuse through the pore structure before undergoing reaction increases as a result.Charles G. Hill, An Introduction To Chemical Engine Design, John Wiley & Sons Inc., 1977 , page 464 As a result, poisoned sites can no longer accelerate the reaction with which the catalyst was supposed to catalyze.

BPA Free Plastic BPS is used in curing fast-drying epoxy glues and as a corrosion inhibitor. It is also commonly used as a reactant in polymer reactions. BPS has become increasingly common as a building block in polycarbonates and some epoxies, following the public awareness that BPA has estrogen-mimicking properties, and widespread-belief that enough of it remains in the products to be dangerous. However, BPS may have comparable estrogenic effects to BPA.

Measurement of acute-phase proteins, especially C-reactive protein, is a useful marker of inflammation in both medical and veterinary clinical pathology. It correlates with the erythrocyte sedimentation rate (ESR), however not always directly. This is due to the ESR being largely dependent on elevation of fibrinogen, an acute phase reactant with a half-life of approximately one week. This protein will therefore remain higher for longer despite removal of the inflammatory stimuli.

Leak-damaged alkaline battery Many battery chemicals are corrosive, poisonous or both. If leakage occurs, either spontaneously or through accident, the chemicals released may be dangerous. For example, disposable batteries often use a zinc "can" both as a reactant and as the container to hold the other reagents. If this kind of battery is over- discharged, the reagents can emerge through the cardboard and plastic that form the remainder of the container.

One way is the synthesis from cinnamyl alcohol 1 and vinyl acetate. This reaction is catalyzed by the enzyme triacylglycerol ester hydrolase, which is a lipase that is very specific towards the ester bond. The byproduct of this reaction is acetaldehyde. The reaction equation for this reaction is: :: 490x490px Since acetaldehyde has an unfavourable deactivating effect on the lipase used in the synthesis, ethyl acetate can be used as reactant instead of vinyl acetate.

A cellular precipitation reaction, in which a reactant phase decomposes to a product phase with the same structure as the parent phase and a second phase with a different structure, can form a symplectite.Sundquist, B. E. (1973), Cellular precipitation, Metall. Trans., 4, 1919– 1934. Eutectoid reactions, involving the breakdown of a single phase to two or more phases, neither of which is structurally or compositionally identical to the parent phase, can also form symplectites.

Efforts to develop water-soluble and "green" total syntheses are also being explored, with the first of these methods implementing polyethylenimine (PEI)-coated nanoparticles. Thermal decomposition uses high temperature solvents to decompose molecular precursors into nuclei, which grow at roughly the same rate, yielding high quality, monodisperse NPs. Growth is guided by precursor decomposition kinetics and Oswald ripening, allowing for fine control over particle size, shape and structure by temperature and reactant addition and identity.

The major advantage of using CTC is it requires a single molecule; however, the required reaction conditions and catalyst compatibility are major hurdles. The system must be thoroughly studied to find the optimal conditions for both the catalysis and reactant to produce the desired product. Occasionally, a trade-off must be made between several competing effects. The desire of getting better yields and selectivity is of interest to many in academia and the industry.

Basically, three traditional methods of enzyme immobilization can be distinguished: binding to a support(carrier), entrapment (encapsulation) and cross-linking. Support binding can be physical, ionic, or covalent in nature. However, physical bonding is generally too weak to keep the enzyme fixed to the carrier under industrial conditions of high reactant and product concentrations and high ionic strength. The support can be a synthetic resin, a biopolymer or an inorganic polymer such as (mesoporous) silica or a zeolite.

The Tiffeneau-Demjanov rearrangement (after Marc Tiffeneau and Nikolai Demjanov) is a variation of the Demjanov rearrangement, which involves both a ring expansion and the production of a ketone by using sodium nitrite and hydrogen cation. Using the Tiffeneau-Demjanov reaction is often advantageous as, while there are rearrangements possible in the products, the reactant always undergoes ring enlargement. As in the Demjanov rearrangement, products illustrate regioselectivity in the reaction. Migratory aptitudes of functional groups dictate rearrangement products.

The hot gas temperatures in the pulsation reactor range from 250° - 1,350 °C (expansion to higher temperatures is in progress). However, the actual treatment temperature may differ significantly from these values after the reactant has been added. The necessary treatment temperature can be determined through systematic experiments with temperature variation. In addition to the treatment temperature and the type of hot gas atmosphere, pulsation reactors also provide the option of adjusting the frequency and amplitude of the pulsation (i.e.

Chain transfer was first proposed by Taylor and Jones in 1930. They were studying the production of polyethylene [()n] from ethylene [] and hydrogen [] in the presence of ethyl radicals that had been generated by the thermal decomposition of (Et)2Hg and (Et)4Pb. The observed product mixture could be best explained by postulating "transfer" of radical character from one reactant to another. Flory incorporated the radical transfer concept in his mathematical treatment of vinyl polymerization in 1937.

The experimentally determined rate law refers to the stoichiometry of the transition state structure relative to the ground state structure. Determination of the rate law was historically accomplished by monitoring the concentration of a reactant during a reaction through gravimetric analysis, but today it is almost exclusively done through fast and unambiguous spectroscopic techniques. In most cases, the determination of rate equations is simplified by adding a large excess ("flooding") all but one of the reactants.

Zinc electrolyte paste or pellets are pushed into a chamber, and waste zinc oxide is pumped into a waste tank or bladder inside the fuel tank. Fresh zinc paste or pellets are taken from the fuel tank. The zinc oxide waste is pumped out at a refueling station for recycling. Alternatively, this term may refer to an electrochemical system in which zinc is a co-reactant assisting the reformation of hydrocarbons at the anode of a fuel cell.

Solvents can affect rates through equilibrium-solvent effects that can be explained on the basis of the transition state theory. In essence, the reaction rates are influenced by differential solvation of the starting material and transition state by the solvent. When the reactant molecules proceed to the transition state, the solvent molecules orient themselves to stabilize the transition state. If the transition state is stabilized to a greater extent than the starting material then the reaction proceeds faster.

The physical state (solid, liquid, or gas) of a reactant is also an important factor of the rate of change. When reactants are in the same phase, as in aqueous solution, thermal motion brings them into contact. However, when they are in separate phases, the reaction is limited to the interface between the reactants. Reaction can occur only at their area of contact; in the case of a liquid and a gas, at the surface of the liquid.

This measure has also been called surprisal, as it represents the "surprise" of seeing the outcome (a highly improbable outcome is very surprising). This term (as a log-probability measure) was coined by Myron Tribus in his 1961 book Thermostatics and Thermodynamics.R. B. Bernstein and R. D. Levine (1972) "Entropy and Chemical Change. I. Characterization of Product (and Reactant) Energy Distributions in Reactive Molecular Collisions: Information and Entropy Deficiency", The Journal of Chemical Physics 57, 434-449 link.

The reactions are balanced and include EC numbers, reaction direction, predicted atom mappings that describe the correspondence between atoms in the reactant compounds and the product compounds, and computed Gibbs free energy. All objects in MetaCyc are clickable and provide easy access to related objects. For example, the page for L-lysine lists all of the reactions in which L-lysine participates, as well as the enzymes that catalyze them and pathways in which these reactions take place.

In an ideal chemical process, the amount of starting materials or reactants equals the amount of all products generated and no atom is lost. However, in most processes, some of the consumed reactant atoms do not become part of the products, but remain as unreacted reactants, or are lost in some side reactions. Besides, solvents and energy used for the reaction are ignored in this calculation, but they may have non-negligible impacts to the environment.

Karl Marx noted that large scale manufacturing allowed economical use of products that would otherwise be waste. Marx cited the chemical industry as an example, which today along with petrochemicals, remains highly dependent on turning various residual reactant streams into salable products. In the pulp and paper industry it is economical to burn bark and fine wood particles to produce process steam and to recover the spent pulping chemicals for conversion back to a usable form.

When a reactant can form two different products depending on the reaction conditions, it becomes important to choose the right conditions to favor the desired product. If a reaction is carried out at relatively lower temperature, then the product formed is one lying across the smaller energy barrier. This is called kinetic control and the ratio of the products formed depends on the relative energy barriers leading to the products. Relative stabilities of the products do not matter.

RNase PH is a tRNA nucleotidyltransferase, present in archaea and bacteria, that is involved in tRNA processing. Contrary to hydrolytic enzymes, it is a phosphorolytic enzyme, meaning that it uses inorganic phosphate as a reactant to cleave nucleotide-nucleotide bonds, releasing diphosphate nucleotides. The active structure of the proteins is a homohexameric complex, consisting of three ribonuclease (RNase) PH dimers. RNase PH has homologues in many other organisms, which are referred to as RNase PH-like proteins.

Solvolysis is a type of nucleophilic substitution (SN1/SN2) or elimination where the nucleophile is a solvent molecule. Characteristic of SN1 reactions, solvolysis of a chiral reactant affords the racemate. Sometimes however, the stereochemical course is complicated by intimate ion pairs, whereby the leaving anion remains close to the carbocation, effectively shielding it from an attack by the nucleophile. Particularly fast reactions can occur by neighbour group participation, with nonclassical ions as intermediates or transition states.

MOCVD apparatus In the metal organic chemical vapor deposition (MOCVD) technique, reactant gases are combined at elevated temperatures in the reactor to cause a chemical interaction, resulting in the deposition of materials on the substrate. A reactor is a chamber made of a material that does not react with the chemicals being used. It must also withstand high temperatures. This chamber is composed by reactor walls, liner, a susceptor, gas injection units, and temperature control units.

Chemical ionization requires a lower amount of energy compared to electron ionization (EI), but this depends on the reactant material used. This low-energy ionization mechanism yields less or sometimes no fragmentation, and usually a simpler spectrum. The lack of fragmentation limits the amount of structural information that can be determined about the ionized species. However, a typical CI spectrum has an easily identifiable protonated molecular ion peak [M+1]+, which allows easy determination of molecular mass.

As the concentration of CO is increased, the frequency of successful collisions of that reactant would increase also, allowing for an increase in forward reaction, and generation of the product. Even if the desired product is not thermodynamically favored, the end-product can be obtained if it is continuously removed from the solution. The effect of a change in concentration is often exploited synthetically for condensation reactions (i.e., reactions that extrude water) that are equilibrium processes (e.g.

Additionally, the chemical environment of the nanoparticle plays a large role on the catalytic properties. With this in mind, it is important to note that heterogeneous catalysis takes place by adsorption of the reactant species to the catalytic substrate. When polymers, complex ligands, or surfactants are used to prevent coalescence of the nanoparticles, the catalytic ability is frequently hindered due to reduced adsorption ability. However, these compounds can also be used in such a way that the chemical environment enhances the catalytic ability.

Scheme 2. Doebner-Miller reaction mechanism The fragmentation to 4a and 4b is key to this mechanism because it explains the isotope scrambling results. In the reaction only half the pulegone reactant (2) is labeled and on recombining a labeled imine fragment can react with another labeled ketone fragment or an unlabeled fragment and likewise a labeled ketone fragment can react with a labeled or unlabeled imine fragment. The resulting product distribution is confirmed by mass spectrometry of the final product 9.

Aminoallyl NTPs are used for indirect DNA labeling in PCR, nick translation, primer extensions and cDNA synthesis. These labeled NTPs are helpful because of their application in molecular biology labs where they do not have the capacity to handle radioactive material. For example, 5-(3-Aminoallyl)-Uridine(AA-UTPs) are more effective for high density labeling of DNA than pre-labeling the DNA. After the enzymatic addition of the NTPs, amine reactant fluorescent dyes can be added for detection of the DNA molecule.

A flowing afterglow is an ion source that is used to create ions in a flow of inert gas, typically helium or argon. Flowing afterglow ion sources usually consist of a dielectric discharge that gases are channeled through to be excited and thus made into plasma. Flowing afterglow ion sources can be coupled with a selected-ion flow- tube for selection of reactant ions. When this ion source is coupled with mass spectrometry it is referred to as flowing afterglow mass spectrometry.

Its chief drawback is the need for in situ processes to have the reactant on demand. To speed the process, trace amounts of a nontoxic catalyst composed of iron and tetroamido macrocyclic ligands are combined with sodium carbonate and bicarbonate and converted into a spray. The spray formula is applied to an infested area and is followed by another spray containing tert-butyl hydroperoxide. Using the catalyst method, a complete destruction of all anthrax spores can be achieved in under 30 minutes.

Reduction of ZrO2 and HfO2 to their respective diborides can also be achieved via metallothermic reduction. Inexpensive precursor materials are used and reacted according to the reaction below: ZrO2 \+ B2O3 \+ 5Mg → ZrB2 \+ 5MgO Mg is used as a reactant in order to allow for acid leaching of unwanted oxide products. Stoichiometric excesses of Mg and B2O3 are often required during metallothermic reductions in order to consume all available ZrO2. These reactions are exothermic and can be used to produce the diborides by SHS.

Virtual breakdown mechanism is a concept in the field of electrochemistry. In electrochemical reactions, when the cathode and the anode are close enough to each other (i.e., so-called "nanogap electrochemical cells"), the double layer regions from the two electrodes can be overlapped, forming large electric field uniformly distributed inside the entire electrode gap. Such high electric field can significantly enhance the ion migration inside bulk solution, and thus facilitate the entire reaction rate, performing like "breakdown" of the reactant(s).

Biosynthesis of α-terpinene. "P" indicates a phosphate group, -PO32− The biosynthesis of α-terpinene and other terpenoids occurs via the mevalonate pathway because its starting reactant, dimethylallyl pyrophosphate (DMAPP), is derived from mevalonic acid. Geranyl pyrophosphate (GPP) is produced from the reaction of a resonance-stable allylic cation, formed from the loss of the pyrophosphate group from DMAPP, and isopentenyl pyrophosphate (IPP), and the subsequent loss of a proton. GPP then loses the pyrophosphate group to form the resonance-stable geranyl cation.

The strength of polymer chains can be enhanced by cross-linking, which increases the interactions between chains through bonding with another reactant. The high mechanical strength of soil/polymer mixtures after cross- linking can make many polymers more suited for soil stabilization projects. Curing time after polymer addition can also affect the strength of the polymer-soil structures formed. After seven days of curing, the liquid polymer SS299 resulted in soil with two times the compressive strength of untreated soil.

Its reaction mechanism centers around dissociation of the reactant with the positively charged organic residue R attacking the aniline ring in a Friedel–Crafts alkylation. In one study this rearrangement was applied to a 3-N(CH3)(C6H5)-2-oxindole:heating 1 in toluene at 80 °C gives 30% 2-o (ortho) and 37% 2-p (para) :Hofmann–Martius rearrangement of 3-N-Aryl-2-oxindoles The reaction is named after German chemists August Wilhelm von Hofmann and Carl Alexander von Martius.

Later workers derived additional methods for generating random numbers according to Gillespie's function p(τ,j) which offer computational advantages in various specific situations. Gillespie's original derivation of the SSA applied only to a well-stirred dilute gas. It was widely assumed/hoped that the SSA would also apply when the reactant molecules are solute molecules in a well-stirred dilute solution, a case more appropriate to cellular chemistry. In fact it does, but that was not definitively established until 2009.

The original and still a commonly practised form of hydrogenation in teaching laboratories, this process is usually effected by adding solid catalyst to a round bottom flask of dissolved reactant which has been evacuated using nitrogen or argon gas and sealing the mixture with a penetrable rubber seal. Hydrogen gas is then supplied from a H2-filled balloon. The resulting three phase mixture is agitated to promote mixing. Hydrogen uptake can be monitored, which can be useful for monitoring progress of a hydrogenation.

Fluorine forms very strong bonds with many elements. With sulfur it can form the extremely stable and chemically inert sulfur hexafluoride; with carbon it can form the remarkable material Teflon that is a stable and non-combustible solid with a high melting point and a very low coefficient of friction that makes it an excellent liner for cooking pans and raincoats. Fluorine-carbon compounds include some unique plastics. it is also used as a reactant in the making of toothpaste.

The height of energy barrier is always measured relative to the energy of the reactant or starting material. Different possibilities have been shown in figure 6. Figure 6:Reaction Coordinate Diagrams showing reactions with 0, 1 and 2 intermediates: The double-headed arrow shows the first, second and third step in each reaction coordinate diagram. In all three of these reactions the first step is the slow step because the activation energy from the reactants to the transition state is the highest.

While not as abundant in the atmosphere as carbon dioxide, it is, for an equivalent mass, nearly 300 times more potent in its ability to warm the planet. Ammonia (NH3) in the atmosphere has tripled as the result of human activities. It is a reactant in the atmosphere, where it acts as an aerosol, decreasing air quality and clinging to water droplets, eventually resulting in nitric acid (HNO3) that produces acid rain. Atmospheric ammonia and nitric acid also damage respiratory systems.

The aromatization of acyclic precursors is rarer in organic synthesis, although it is a significant component of the BTX production in refineries. Among acyclic precursors, alkynes are relatively prone to aromatizations since they are partially dehydrogenated. The Bergman cyclization is converts an enediyne to a dehydrobenzene intermediate diradical, which abstracts hydrogen to aromatize. The enediyne moiety can be included within an existing ring, allowing access to a bicyclic system under mild conditions as a consequence of the ring strain in the reactant.

The series of steps together make a reaction mechanism. A reactive intermediate differs from a reactant or product or a simple reaction intermediate only in that it cannot usually be isolated but is sometimes observable only through fast spectroscopic methods. It is stable in the sense that an elementary reaction forms the reactive intermediate and the elementary reaction in the next step is needed to destroy it. When a reactive intermediate is not observable, its existence must be inferred through experimentation.

Often a so-called sacrificial catalyst is also part of the reaction system with the purpose of regenerating the true catalyst in each cycle. As the name implies, the sacrificial catalyst is not regenerated and is irreversibly consumed, thereby not a catalyst at all. This sacrificial compound is also known as a stoichiometric catalyst when added in stoichiometric quantities compared to the main reactant. Usually the true catalyst is an expensive and complex molecule and added in quantities as small as possible.

Since a molecule can form two enantiomers around a chiral center, the Walden inversion converts the configuration of the molecule from one enantiomeric form to the other. For example, in an SN2 reaction, Walden inversion occurs at a tetrahedral carbon atom. It can be visualized by imagining an umbrella turned inside-out in a gale. In the Walden inversion, the backside attack by the nucleophile in an SN2 reaction gives rise to a product whose configuration is opposite to the reactant.

An important use of adipoyl chloride is polymerization with an organic di-amino compound to form a polyamide called nylon or polymerization with certain other organic compounds to form polyesters. Phosgene (carbonyl dichloride, Cl–CO–Cl) is a very toxic gas that is the dichloride of carbonic acid (HO–CO–OH). Both chloride radicals in phosgene can undergo reactions analogous to the preceding reactions of acyl halides. Phosgene is used a reactant in the production of polycarbonate polymers, among other industrial applications.

When chlorobenzene is hydrodechlorinated over nickel and silica, highly ordered structures of filamentous carbon form. When potassium and bromine are present, this reaction can occur at temperatures as low as . This is because the potassium and bromine aided in restructuring the active sites, thus causing destructive chemisorption of the reactant and also causing the a precipitate of carbon to form. Adding potassium hydroxide to the mixture of nickel and silica in the reaction made little change to the yield of the reaction.

When one reactant contains hydrogen atoms, a reaction can take place by exchanging protons in acid-base chemistry. In a more general definition, any chemical species capable of binding to electron pairs is called a Lewis acid; conversely any molecule that tends to donate an electron pair is referred to as a Lewis base. As a refinement of acid-base interactions, the HSAB theory takes into account polarizability and size of ions. Inorganic compounds are found in nature as minerals.

Both processes require high ratios of water to the amount of feedstock. This energy profligacy can be avoided by the use of a plastic-type extruder through which the solid, but wet, biomass is conveyed to a small inductively heated reaction zone as shown by Xtrudx Technologies Inc of Seattle. Supercritical hydrolysis can be considered a broadly applicable green chemistry process that utilizes water simultaneously as a heat transfer agent, a solvent, a reactant, a source of hydrogen and as a char-reduction component.

Umesterung von Acrylaten mit Dimethylaminoethanol During the reaction, inhibitors must be present (such as phenothiazine), because of the high tendency of starting material and product to polymerize. When ethyl acrylate is used as a reactant, ethanol is formed; this forms with the ethyl acrylate an azeotrope of the composition ethanol/ethyl acrylate 72.7:26.3%, which boils at 77.5 ° C under atmospheric pressure.Technical Data Sheet, Ethyl Acrylate, BASF AG, June 2002. To achieve a high reaction yield, the ethanol is distilled off from the reaction mixture.

The finished product is separated in a cleanable filter. The product can be removed throughout the ongoing process using a sluice system and collected in barrels or big bags. The risk of the product contaminating the environment can be completely excluded through the vacuum present in the reactor, including the filter. 400px An almost tube-like flow with an almost constant temperature across the pipe diameter is generated in the resonance tube (the treatment area for the reactant) through the pulsating flow of hot gas.

As a result, the yield should not be automatically taken as a measure for reaction efficiency. In their 1992 publication General Chemistry, Whitten, Gailey, and Davis described the theoretical yield as the amount predicted by a stoichiometric calculation based on the number of moles of all reactants present. This calculation assumes that only one reaction occurs and that the limiting reactant reacts completely. According to Whitten, the actual yield is always smaller (the percent yield is less than 100%), often very much so, for several reasons.

This powerful carbon-carbon bond forming cross-coupling reactions combines an organic halide and an organozinc halide reagent in the presence of a nickel or palladium catalyst. The organic halide reactant can be alkenyl, aryl, allyl, or propargyl. Alkylzinc coupling with alkyl halides such as bromides and chlorides have also been reported with active catalysts such as Pd-PEPPSI precatalysts, which strongly resist beta-hydride elimination (a common occurrence with alkyl substituents).S. Sase, M. Jaric, A. Metzger, V. Malakhov, P. Knochel, J. Org. Chem.

When seco acid is added into the system little by little using a syringe driver, all of the reactant is quickly converted into MA; then, the MA is immediately consumed by the cyclization reaction. As just described, MA concentration is kept low throughout the Shiina macrolactonization reaction. Therefore, the monomer production rate is very high. Aromatic carboxylic acid anhydrides are used as dehydration condensation agents not only for the intramolecular reaction of hydroxycarboxylic acids but also for the intermolecular reaction of carboxylic acids with alcohols (Shiina esterification).

An example of a selective reaction is oxidation of ethylbenzene to acetophenone, with no evidence of formation of phenylethanoic acid, or of pyrolysis products. Several different types of reaction in which water was behaving as reactant, catalyst and solvent were described by Katritzky et al. Triglycerides can be hydrolysed to free fatty acids and glycerol by superheated water at 275 °C, which can be the first in a two-stage process to make biodiesel. Superheated water can be used to chemically convert organic material into fuel products.

Inflammatory cells and red blood cells Acute-phase proteins (APPs) are a class of proteins whose plasma concentrations increase (positive acute-phase proteins) or decrease (negative acute-phase proteins) in response to inflammation. This response is called the acute-phase reaction (also called acute-phase response). The acute-phase reaction characteristically involves fever, acceleration of peripheral leukocytes, circulating neutrophils and their precursors. The terms acute-phase protein and acute-phase reactant (APR) are often used synonymously, although some APRs are (strictly speaking) polypeptides rather than proteins.

The specific enzymes are named from one of the reactant pairs, for example; the reaction between glutamic acid and pyruvic acid to make alpha ketoglutaric acid and alanine is called glutamic-pyruvic transaminase or GPT for short. Tissue transaminase activities can be investigated by incubating a homogenate with various amino/keto acid pairs. Transamination is demonstrated if the corresponding new amino acid and keto acid are formed, as revealed by paper chromatography. Reversibility is demonstrated by using the complementary keto/amino acid pair as starting reactants.

Temperature usually has a major effect on the rate of a chemical reaction. Molecules at a higher temperature have more thermal energy. Although collision frequency is greater at higher temperatures, this alone contributes only a very small proportion to the increase in rate of reaction. Much more important is the fact that the proportion of reactant molecules with sufficient energy to react (energy greater than activation energy: E > Ea) is significantly higher and is explained in detail by the Maxwell-Boltzmann distribution of molecular energies.

Consequently, the deuterium-tritium fuel cycle requires the breeding of tritium from lithium using one of the following reactions: : + → + : + → + + The reactant neutron is supplied by the D-T fusion reaction shown above, and the one that has the greatest yield of energy. The reaction with 6Li is exothermic, providing a small energy gain for the reactor. The reaction with 7Li is endothermic but does not consume the neutron. At least some neutron multiplication reactions are required to replace the neutrons lost to absorption by other elements.

Most photopolymerization reactions are chain-growth polymerizations which are initiated by the absorption of visible or ultraviolet light. The light may be absorbed either directly by the reactant monomer (direct photopolymerization), or else by a photosensitizer which absorbs the light and then transfers energy to the monomer. In general only the initiation step differs from that of the ordinary thermal polymerization of the same monomer; subsequent propagation, termination and chain transfer steps are unchanged.Allcock H.R., Lampe F.W. and Mark J.F. Contemporary Polymer Chemistry (3rd ed.

Given the ubiquity of hydrogen atoms in inorganic and organic chemical compounds, the hydrogen cycle is focused on molecular hydrogen, H2. Hydrogen gas can be produced naturally through rock-water interactions or as a byproduct of microbial metabolisms. Free H2 can then be consumed by other microbes, oxidized photochemically in the atmosphere, or lost to space. Hydrogen is also thought to be an important reactant in pre-biotic chemistry and the early evolution of life on Earth, and potentially elsewhere in our solar system.

This is many times more than what was needed to overcome the energy barrier. The fusion reaction rate increases rapidly with temperature until it maximizes and then gradually drops off. The DT rate peaks at a lower temperature (about 70 keV, or 800 million kelvin) and at a higher value than other reactions commonly considered for fusion energy. The reaction cross section (σ) is a measure of the probability of a fusion reaction as a function of the relative velocity of the two reactant nuclei.

It takes more energy to reach the transition state of a reaction if the compound has bonds with a heavier isotope, which causes the compound with heavier isotopes to react more slowly. Normal kinetic isotope effects cause the lighter isotope (or isotopes) to be preferentially included in a reaction's product. The products are then said to be "depleted" in the heavy isotope relative to the reactant. Rarely, inverse kinetic isotope effects may occur, where the heavier isotope is preferentially included in a reaction's product.

Chemical decomposition, or chemical breakdown, is the process or effect of simplifying a single chemical entity (normal molecule, reaction intermediate, etc.) into two or more fragments. Chemical decomposition is usually regarded and defined as the exact opposite of chemical synthesis. In short, the chemical reaction in which two or more products are formed from a single reactant is called a decomposition reaction. The details of a decomposition process are not always well defined but some of the process is understood; much energy is needed to break bonds.

The formation of the resonance- stabilized Meisenheimer complex is slow because it is in a higher energy state than the aromatic reactant. The loss of the chloride is fast, because the ring becomes aromatic again. Recent work indicates that, sometimes, the Meisenheimer complex is not always a true intermediate but may be the transition state of a 'frontside SN2' process, particularly if stabilization by electron-withdrawing groups is not very strong. A 2019 review argues that such 'concerted SNAr' reactions are more prevalent than previously assumed.

Therefore, the stabilizing effect of the methyl groups on the cyclopentadienyl rings is of great importance in the formation of decamethydizincocene. The use of ZnEt2 as a reactant is of particular significance. The organozinc precursor is important. Diphenylzinc (Zn(C6H5)2), despite its lower solubility, can be utilized in place of ZnEt2. On the other hand, ZnMe2 gives only the half- sandwich compound [(η5-C5Me5)ZnMe]. Both (η5-C5Me5)ZnEt and decamethyldizincocene are produced from the reaction between Zn(η5-C5Me5)2 and ZnEt2.

The catalysts used for catalytic distillation are composed of different substances and packed onto varying objects. The majority of the catalysts are powdered acids, bases, metal oxides, or metal halides. These substances tend to be highly reactive which can significantly speed up the rate of the reaction making them effective catalysts. The shapes which the catalysts are packed onto must be able to form a consistent geometric arrangement to provide equal spacing in the catalyst bed (an area in the distillation column where the reactant and catalyst come into contact to form the products).

The exact value of the CCD depends on the solubility of calcium carbonate which is determined by temperature, pressure and the chemical composition of the water – in particular the amount of dissolved in the water. Calcium carbonate is more soluble at lower temperatures and at higher pressures. It is also more soluble if the concentration of dissolved is higher. Adding a reactant to the above chemical equation pushes the equilibrium towards the right producing more products: Ca2+ and HCO3−, and consuming more reactants and calcium carbonate according to Le Chatelier's principle.

Several factors affect the activity of enzymes (and other catalysts) including temperature, pH, concentration of enzyme, substrate, and products. A particularly important reagent in enzymatic reactions is water, which is the product of many bond- forming reactions and a reactant in many bond-breaking processes. In biocatalysis, enzymes are employed to prepare many commodity chemicals including high-fructose corn syrup and acrylamide. Some monoclonal antibodies whose binding target is a stable molecule which resembles the transition state of a chemical reaction can function as weak catalysts for that chemical reaction by lowering its activation energy.

85–91, 2002. (Online article) PK reaction with Wilkinson's catalyst Molybdenum hexacarbonyl is a carbon monoxide donor in PK-type reactions between allenes and alkynes with dimethyl sulfoxide in toluene. PK reaction with molybdenum hexacarbonyl Cyclobutadiene also lends itself to a [2+2+1] cycloaddition although this reactant is generated in situ from decomplexation of stable cyclobutadiene iron tricarbonyl with ceric ammonium nitrate (CAN).Intramolecular [2+2+1] Cycloadditions with (Cyclobutadiene)tricarbonyliron Benjamin A. Seigal, Mi Hyun An, Marc L. Snapper Angewandte Chemie International Edition Volume 44, Issue 31 , Pages 4929 - 4932 2005.

For SN2 reactions, alkyl alcohols can also be converted to alkyl tosylates, often through addition of tosyl chloride. In this reaction, the lone pair of the alcohol oxygen attacks the sulfur of the tosyl chloride, displacing the chloride and forming the tosylate with retention of reactant stereochemistry. This is useful because alcohols are poor leaving groups in SN2 reactions, in contrast to the tosylate group. It is the transformation of alkyl alcohols to alkyl tosylates that allows an SN2 reaction to occur in the presence of a good nucleophile.

The resulting 1-substituted 3,4-dihydroisoquinoline can then be dehydrogenated using palladium. The following Bischler–Napieralski reaction produces papaverine. 800px The Pictet–Gams reaction and the Pictet–Spengler reaction are both variations on the Bischler–Napieralski reaction. A Pictet–Gams reaction works similarly to the Bischler–Napieralski reaction; the only difference being that an additional hydroxy group in the reactant provides a site for dehydration under the same reaction conditions as the cyclization to give the isoquinoline rather than requiring a separate reaction to convert a dihydroisoquinoline intermediate.

Francke et al. provide an excellent example as to why the verification step of the project needs to be performed in significant detail. During a metabolic network reconstruction of Lactobacillus plantarum, the model showed that succinyl-CoA was one of the reactants for a reaction that was a part of the biosynthesis of methionine. However, an understanding of the physiology of the organism would have revealed that due to an incomplete tricarboxylic acid pathway, Lactobacillus plantarum does not actually produce succinyl-CoA, and the correct reactant for that part of the reaction was acetyl-CoA.

Fundamentally, a pulsation reactor can be described as a periodically transient tube-type reactor that can be used to thermally treat gas-borne matter. The pulsating flow of hot gas is generated within a hot gas generator in the reactor by burning natural gas or hydrogen with ambient air. The hot gas flows through the so-called “resonance tube” into which reactants in powder, liquid or gas form can be added. The reactant is treated by hot gas flowing through the resonance tube and this process ends through suitable cooling.

An adaptive enzyme or inducible enzyme is an enzyme that is expressed only under conditions in which it is clearly of adaptive value, as opposed to a constitutive enzyme which is produced all the time. The Inducible enzyme is used for the breaking-down of things in the cell. It is also a part of the Operon Model, which illustrates a way for genes to turn "on" and "off". The Inducer causes the gene to turn on (controlled by the amount of reactant which turns the gene on).

Acid- catalyzed hydrolysis of esters is also an equilibrium process – essentially the reverse of the Fischer esterification reaction. Because an alcohol (which acts as the leaving group) and water (which acts as the nucleophile) have similar pKa values, the forward and reverse reactions compete with each other. As in transesterification, using a large excess of reactant (water) or removing one of the products (the alcohol) can promote the forward reaction. The acid-catalyzed hydrolysis of an ester and Fischer esterification correspond to two directions of an equilibrium process.

The ene reaction In organic chemistry, a group transfer reaction is a pericyclic process where one or more groups of atoms is transferred from one molecule to another. They can sometimes be difficult to identify when separate reactant molecules combine into a single product molecule (like in the ene reaction). Unlike other pericylic reaction classes, group transfer reactions do not have a specific conversion of pi bonds into sigma bonds or vice versa, and tend to be less frequently encountered. Like all pericyclic reactions, they must obey the Woodward–Hoffmann rules.

As ferritin is also an acute-phase reactant, it is often elevated in the course of disease. A normal C-reactive protein can be used to exclude elevated ferritin caused by acute phase reactions. Ferritin has been shown to be elevated in some cases of Covid-19 and may correlate with worse clinical outcome. According to a study of anorexia nervosa patients, ferritin can be elevated during periods of acute malnourishment, perhaps due to iron going into storage as intravascular volume and thus the number of red blood cells falls.

PdII complexes are in fact pre- catalysts since they must be reduced to Pd(0) before catalysis can begin. PdII complexes generally exhibit greater stability than Pd0 complexes and can be stored under normal laboratory conditions for months. PdII catalysts are reduced to Pd0 in the reaction mixture by an amine, a phosphine ligand, or another reactant in the mixture allowing the reaction to proceed. For instance, oxidation of triphenylphosphine to triphenylphosphine oxide can lead to the formation of Pd0 in situ when [Pd(PPh3)2Cl2] is used.

The SSA is one component of stochastic chemical kinetics, a field that Gillespie played a major role in developing and clarifying through his later publications. The SSA is physically accurate only for systems that are both dilute and well- mixed in the reactant (solute) molecules. An extension of the SSA which is aimed at circumventing the globally well-mixed requirement is the reaction- diffusion SSA (RD-SSA). It subdivides the system volume into cubic subvolumes or “voxels” which are small enough that each can be considered well-mixed.

In a solid, only those particles that are at the surface can be involved in a reaction. Crushing a solid into smaller parts means that more particles are present at the surface, and the frequency of collisions between these and reactant particles increases, and so reaction occurs more rapidly. For example, Sherbet (powder) is a mixture of very fine powder of malic acid (a weak organic acid) and sodium hydrogen carbonate. On contact with the saliva in the mouth, these chemicals quickly dissolve and react, releasing carbon dioxide and providing for the fizzy sensation.

As noted below, energy is released by the hydrolysis of ATP. However, when the P-O bonds are broken, input of energy is required. It is the formation of new bonds and lower-energy inorganic phosphate with a release of a larger amount of energy that lowers the total energy of the system and makes it more stable. Hydrolysis of the phosphate groups in ATP is especially exergonic, because the resulting orthophosphate molecular ion is greatly stabilized by multiple resonance structures, making the products (ADP and Pi) lower in energy than the reactant (ATP).

A spectator ion is an ion that exists as a reactant and a product in a chemical equation. A spectator ion can, therefore, be observed in the reaction of aqueous solutions of sodium carbonate and copper(II) sulfate but does not affect the equilibrium: :2 (aq) \+ (aq) \+ (aq) \+ (aq) → 2 (aq) \+ (aq) \+ (s) The and ions are spectator ions since they remain unchanged on both sides of the equation. They simply "watch" the other ions react, hence the name. They are present in total ionic equations to balance the charges of the ions.

Since 5β-coprostanol is formed from cholesterol in the vertebrate gut, the ratio of the product over reactant can be used to indicate the degree of faecal matter in samples. Raw untreated sewage typically has a 5β-coprostanol / cholesterol ratio of ~10 which decreases through a sewage treatment plant (STP) such that in the discharged liquid wastewaters the ratio is ~2. Undiluted STP wastewaters may be identified by this high ratio. As the faecal matter is dispersed in the environment, the ratio will decrease as more (non-faecal) cholesterol from animals is encountered.

Terrence W. Deacon, Alok Srivastava, and J. Augustus Bacigalupi Autogen pg 339 Reciprocal catalysis: An autogen consists of two self catalyzing cyclical morphodynamic chemical reactions, similar to a chemoton. In one reaction, organic molecules react in a looped series, the products of one reaction becoming the reactants for the next. This looped reaction is self amplifying, producing more and more reactants until all the substrate is consumed. A side product of this reciprocally catalytic loop is a lipid that can be used as a reactant in a second reaction.

A reaction with ∆H°<0 is called exothermic reaction while one with ∆H°>0 is endothermic. Figure 8: Reaction Coordinate Diagrams showing favorable or unfavorable and slow or fast reactions The relative stability of reactant and product does not define the feasibility of any reaction all by itself. For any reaction to proceed, the starting material must have enough energy to cross over an energy barrier. This energy barrier is known as activation energy (∆G≠) and the rate of reaction is dependent on the height of this barrier.

However, the polymer obtained in this manner is unstable in that it leads to changes in molecular weight because the ends of the polymer molecule contain functional groups that can react further with each other. This situation is avoided by adjusting the concentrations of the two monomers so that they are slightly nonstoichiometric. One of the reactants is present in slight excess. The polymerization then proceeds to a point at which one reactant is completely used up and all the chain ends possess the same functional group of the group that is in excess.

The principle can be shown graphically by plotting the reaction rate against a property such as the heat of adsorption of the reactant by the catalyst. Such plots pass through a maximum, looking roughly like a triangle or an inverted parabola, and are called volcano plots because of their shape. Analogous three-dimensional plots can also be built against two different properties, such as the heats of adsorption of the two reactants for a two- component reaction. In that case the plot is generally shown as a contour plot and is called a volcano surface.

Since different isotopes have different masses, the bond energies are different between different isotopologues of a chemical species. This will result in a difference in the rate of a reaction for the different isotopologues, resulting in a fractionation of the different isotopes between the reactant and product in a chemical reaction. This is known as the kinetic isotope effect. A classic example of such an isotope effect is the D/H ratio difference in the equilibrium between HO and H which can have an alpha value of as much as 3–4.

The transition metals and their compounds are known for their homogeneous and heterogeneous catalytic activity. This activity is ascribed to their ability to adopt multiple oxidation states and to form complexes. Vanadium(V) oxide (in the contact process), finely divided iron (in the Haber process), and nickel (in catalytic hydrogenation) are some of the examples. Catalysts at a solid surface (nanomaterial-based catalysts) involve the formation of bonds between reactant molecules and atoms of the surface of the catalyst (first row transition metals utilize 3d and 4s electrons for bonding).

An instructive example is found in the last part of the total synthesis of monensin by Kishi in 1979: 850px The left-hand reactant possesses two potential electrophilic sites: an aldehyde (indicated in blue) and an ester (indicated in green). Only the aldehyde, which is more electrophilic, will react with the enolate of the methyl ketone in the other part of the molecule. The methyl ester remains untouched. Of course, other effects can play a role in this selectivity process, including electronic effects, steric effects, and thermodynamic versus kinetic reaction control.

Variational transition-state theory is a refinement of transition-state theory. When using transition-state theory to estimate a chemical reaction rate, the dividing surface is taken to be a surface that intersects a first- order saddle point and is also perpendicular to the reaction coordinate in all other dimensions. When using variational transition-state theory, the position of the dividing surface between reactant and product regions is variationally optimized to minimize the reaction rate. This minimizes the effects of recrossing, and gives a much more accurate result.

Amcinonide is produced from the reaction of 16α,17α-Cyciopentylidenedioxy-9α-fluoro-11β,21-dihydroxy-1,4pregnadiene-3,20-dione and acetic anhydride in which 11.1g and 5.5mL, respectively, of each reactant are consumed to produce 7.0g of pure product. Only 4.7% of patients in clinical trials reported experiencing side effects as a result of continued use of Amcinonide. Specifically, in one acceptability study conducted on a weekly basis, one-fifth of patients using both placebo and Cyclocort 0.1% lotion reported various discomforts at multiple interviews.DrugBank.ca:Cyclocort (Amcinonide) The outcomes of relevant trials are included below.

Segregation of granitic melts from their residual solids begins with the onset of partial melting along the grain boundaries of reactant minerals, namely the ferromagnesian phases of micas and amphiboles. Such reactions produce large positive volume changes within the metamorphic system causing melt enhanced embrittlement. This, coupled with an increasing melt fraction, alters the deformation mechanisms acting among grains and decreases the strength of the rock significantly. Melt filled pores eventually coalesce and melt flow parallel to the elongation lineation of grains (or along planes of foliation) is promoted.

The reaction between graphite and thorium dioxide usually takes place in a stream of chlorine gas forming the thorium(IV) chloride. However the chlorination reaction can be done by another compound Cl2-CCl4 which is a more stable reactant than pure Chlorine gas. Cl2-CCl4 is formed by passing a gas mixture of Cl2 through a wash bottle filled with CCl4. ThO2 \+ 2 C + 4 Cl2 → ThCl4 \+ 2 CO Another less common method of synthesis relies on heating thorium metal with NH4Cl at 300 °C for 30 h making a (NH4)2ThCl6.

The oxygen anion in this aldol-like product then does an intramolecular SN2 attack on the formerly-nucleophilic halide-bearing position, displacing the halide to form an epoxide. This reaction sequence is thus a condensation reaction since there is a net loss of HCl when the two reactant molecules join. :800px The primary role of the ester is to enable the initial deprotonation to occur, and other carbonyl functional groups can be used instead. If the starting material is an α-halo amide, the product is an α,β-epoxy amide.

Uranium hexachloride can be synthesized from the reaction of uranium trioxide (UO3) with a mixture of liquid CCl4 and hot chlorine (Cl2). The yield can be increased if the reaction carried out in the presence of UCl5. The UO3 is converted to UCl5, which in turn reacts with the excess Cl2 to form UCl6. It requires a substantial amount of heat for the reaction to take place; the temperature range is from 65 °C to 170 °C depending on the amount of reactant (ideal temperature 100 °C - 125 °C).

The order of the reaction controls how the reactant concentration (or pressure) affects reaction rate. Usually conducting a reaction at a higher temperature delivers more energy into the system and increases the reaction rate by causing more collisions between particles, as explained by collision theory. However, the main reason that temperature increases the rate of reaction is that more of the colliding particles will have the necessary activation energy resulting in more successful collisions (when bonds are formed between reactants). The influence of temperature is described by the Arrhenius equation.

For redox reactions, the equivalent weight of each reactant supplies or reacts with one mole of electrons (e−) in a redox reaction. Equivalent weight has the dimensions and units of mass, unlike atomic weight, which is dimensionless. Equivalent weights were originally determined by experiment, but (insofar as they are still used) are now derived from molar masses. Additionally, the equivalent weight of a compound can be calculated by dividing the molecular mass by the number of positive or negative electrical charges that result from the dissolution of the compound.

The oxidation and reduction of sulfur species often involves the breakage or formation of chemical bonds involving S atoms. Because the thermodynamic stability of certain bonds is often greater when they involve heavier isotopes, an oxidation or reduction reaction can enrich the reactant pool (reservoir) or product pool in compounds containing the heavier isotope, relative to each other. This is known as an isotope effect. The extent to which such a mass-dependent reaction operates in the world's oceans or atmosphere determines how much heavier or lighter various reservoirs of sulfur species will become.

The carbonyl group in the reactant in scheme 8 is masked as a dimethyl acetal and the hydroxyl group is masked as a triisopropylsilyl ether (TIPS). With lewis acid stannic chloride the oxonium ion is activated and the pinacol rearrangement of the resulting Prins intermediate results in ring contraction and referral of the positive charge to the TIPS ether which eventually forms an aldehyde group in the final product as a mixture of cis and trans isomers with modest diastereoselectivity. Scheme 8. Halo-Prins reaction The key oxo-carbenium intermediate can be formed by other routes than simple protonation of a carbonyl.

It rebels against order and tradition. It wanders from its natural course.”Rosenshield, p. 131. “Before Peter, the river lived in an uneventful but primeval existence” and though Peter tries to impose order, the river symbolizes what is natural and tries to return to its original state. “The river resembles Evgenii not as an initiator of violence but as a reactant. Peter has imposed his will on the people (Evgenii) and nature (the Neva) as a means of realizing his imperialistic ambitions” and both Evgenii and the river try to break away from the social order and world that Peter has constructed.

Carbon dioxide reformation (also known as dry reforming) is a method of producing synthesis gas (mixtures of hydrogen and carbon monoxide) from the reaction of carbon dioxide with hydrocarbons such as methane. Synthesis gas is conventionally produced via the steam reforming reaction or coal gasification. In recent years, increased concerns on the contribution of greenhouse gases to global warming have increased interest in the replacement of steam as reactant with carbon dioxide. The dry reforming reaction may be represented by: :CO2 \+ CH4 → 2 H2 \+ 2 CO Thus, two greenhouse gases are consumed and useful chemical building blocks, hydrogen and carbon monoxide, are produced.

In the scheme below, the red carbon is 13C labelled. The symmetric oxirene intermediate can open either way, scrambling the 13C label. If the substituents R1 and R2 are the same, one can quantify the ratio of products stemming from the concerted and stepwise mechanisms; if the substituents are different, the oxirene will have a preference in the direction it opens, and a ratio cannot be quantified, but any scrambling indicates some reactant is going through a stepwise mechanism. In photolysis of diazo acetaldehyde, 8% of the label is scrambled, indicating that 16% of product is formed via the oxirene intermediate.

If the reactant is a cyclic α-diazo ketone, then Wolff-rearrangement products will be the one-carbon ring-contracted product. These reactions are generally concerted due to the s-cis conformation, and are photocatalyzed. The reaction below shows the concerted mechanism for the ring contraction of α-diazocyclohexanone, followed by trapping of the ketene with a weakly acidic nucleophile. Ring contraction of α-diazocyclohexanone via Wolff-rearrangement The first known example is the ring contracted Wolff rearrangement product of α-diazocamphor, and subsequent kinetic hydration of the ketene from the more sterically accessible "endo" face, to give exo-1,5,5-trimethylbicyclo[2.1.

If water is evaporated too quickly, the membrane dries, resistance across it increases, and eventually it will crack, creating a gas "short circuit" where hydrogen and oxygen combine directly, generating heat that will damage the fuel cell. If the water is evaporated too slowly, the electrodes will flood, preventing the reactants from reaching the catalyst and stopping the reaction. Methods to manage water in cells are being developed like electroosmotic pumps focusing on flow control. Just as in a combustion engine, a steady ratio between the reactant and oxygen is necessary to keep the fuel cell operating efficiently.

Its function is to bind the water molecule that produces a nucleophilic attack on the ATP's γ-phosphate bond, while the nucleotide is strongly bound to subdomains 3 and 4. The slowness of the catalytic process is due to the large distance and skewed position of the water molecule in relation to the reactant. It is highly likely that the conformational change produced by the rotation of the domains between actin's G and F forms moves the Glu137 closer allowing its hydrolysis. This model suggests that the polymerization and ATPase's function would be decoupled straight away.

Supercritical hydrolysis is a chemical engineering process in which water in the supercritical state can be employed to achieve a variety of reactions within seconds. To cope with the extremely short times of reaction on an industrial scale, the process should be continuous. This continuity enables the ratio of the amount of water to the other reactant to be less than unity which minimizes the energy needed to heat the water above 374 C, the critical point. Application of the process to biomass provides simple sugars in near quantitative yield by supercritical hydrolysis of the constituent polysaccharides.

The aldol reaction may exhibit "substrate-based stereocontrol", in which existing chirality on either reactant influences the stereochemical outcome of the reaction. This has been extensively studied, and in many cases, one can predict the sense of asymmetric induction, if not the absolute level of diastereoselectivity. If the enolate contains a stereocenter in the alpha position, excellent stereocontrol may be realized. Aldol reaction with enolate-based stereocontrol In the case of an E enolate, the dominant control element is allylic 1,3-strain whereas in the case of a Z enolate, the dominant control element is the avoidance of 1,3-diaxial interactions.

Recall, in this mechanism protonation of the carbanion (either by the conjugate acid or by solvent) is faster than loss of the leaving group. This means after the carbanion is formed, it will quickly remove a proton from the solvent to form the starting material. If the reactant contains deuterium at the β position, a primary kinetic isotope effect indicates that deprotonation is rate determining. Of the three E1cB mechanisms, this result is only consistent with the E1cBirr mechanism, since the isotope is already removed in E1cBanion and leaving group departure is rate determining in E1cBrev.

The concept of plotting the free energies of reaction of various elements with a given gas-phase reactant may be extended beyond oxidation reactions. The original paper by Ellingham explicitly to the reduction of both oxygen and sulfur by metallurgical processes, and anticipated the use of such diagrams for other compounds, including chlorides, carbides, and sulfates. The concept is generally useful for studying the comparative stability of compounds across a range of partial pressures and temperatures. The construction of an Ellingham diagram is especially useful when studying the stability of compounds in the presence of a reductant.

Reactions that proceed in the forward direction to approach equilibrium are often described as spontaneous, requiring no input of free energy to go forward. Non-spontaneous reactions require input of free energy to go forward (examples include charging a battery by applying an external electrical power source, or photosynthesis driven by absorption of electromagnetic radiation in the form of sunlight). Different chemical reactions are used in combinations during chemical synthesis in order to obtain a desired product. In biochemistry, a consecutive series of chemical reactions (where the product of one reaction is the reactant of the next reaction) form metabolic pathways.

A reaction catalyzed by a reductase enzyme Dehydrogenases oxidize a substrate by transferring hydrogen to an electron acceptor, common electron acceptors being NAD+ or FAD. This would be considered an oxidation of the substrate, in which the substrate either loses hydrogen atoms or gains an oxygen atom (from water). The name "dehydrogenase" is based on the idea that it facilitates the removal (de-) of hydrogen (-hydrogen-), and is an enzyme (-ase). Dehydrogenase reactions come most commonly in two forms: the transfer of a hydride and release of a proton (often with water as a second reactant), and the transfer of two hydrogens.

The intramolecular Heck reaction may be used to form rings of a variety of sizes and topologies. β-Hydride elimination need not be the final step of the reaction, and tandem methods have been developed that involve the interception of palladium alkyl intermediates formed after migratory insertion by an additional reactant. This section discusses the most common ring sizes formed by the intramolecular Heck reaction and some of its tandem and asymmetric variants. 5-Exo cyclization, which establishes a five-membered ring with an exocyclic alkene, is the most facile cyclization mode in intramolecular Heck reactions.

Analogously to the in situ IR experiments described above, in situ UV-visible absorbance spectroscopy may be used to monitor the course of a reaction, provided a reagent or product shows distinctive absorbance in the UV spectral region. The rate of reactant consumption and/or product formation may be abstracted from the change of absorbance over time (by application of Beer's Law), again leading to classification as an integral technique. Due to the spectral region utilized, UV-vis techniques are more commonly utilized on inorganic or organometallic systems than on purely organic reactions, and examples include exploration of the samarium Barbier reaction.

Conversion and its related terms yield and selectivity are important terms in chemical reaction engineering. They are described as ratios of how much of a reactant has reacted (X — conversion, normally between zero and one), how much of a desired product was formed (Y — yield, normally also between zero and one) and how much desired product was formed in ratio to the undesired product(s) (S — selectivity). There are conflicting definitions in the literature for selectivity and yield, so each author's intended definition should be verified. Conversion can be defined for (semi-)batch and continuous reactors and as instantaneous and overall conversion.

Friedel–Crafts alkylation involves the alkylation of an aromatic ring with an alkyl halide using a strong Lewis acid, such as aluminium chloride, ferric chloride, or other MXn reagent, as catalyst. The general mechanism for tertiary alkyl halides is shown below. :Mechanism for the Friedel Crafts alkylation For primary (and possibly secondary) alkyl halides, a carbocation-like complex with the Lewis acid, [R(+)\---(X--- MXn)(–)] is more likely to be involved, rather than a free carbocation. This reaction suffers from the disadvantage that the product is more nucleophilic than the reactant because alkyl groups are activators for the Friedel–Crafts reaction.

450 px Correlation diagrams, which connect the molecular orbitals of the reactant to those of the product having the same symmetry, can then be constructed for the two processes.The conservation of orbital symmetry. Acc. Chem. Res., Volume 1, Issue 1, 1968, Pages 17–22 Roald Hoffmann and Robert B. Woodward 850 px These correlation diagrams indicate that only a conrotatory ring opening of 3,4-dimethylcyclobutene is symmetry allowed whereas only a disrotatory ring opening of 5,6-dimethylcyclohexa-1,3-diene is symmetry allowed. This is because only in these cases would maximum orbital overlap occur in the transition state.

If the ring opening of 3,4-dimethylcyclobutene were carried out under photochemical conditions the resulting electrocyclization would be occur through a disrotatory mode instead of a conrotatory mode as can be seen by the correlation diagram for the allowed excited state ring opening reaction. 550px Only a disrotatory mode, in which symmetry about a reflection plane is maintained throughout the reaction, would result in maximum orbital overlap in the transition state. Also, once again, this would result in the formation of a product that is in an excited state of comparable stability to the excited state of the reactant compound.

A proton-exchange membrane, or polymer-electrolyte membrane (PEM), is a semipermeable membrane generally made from ionomers and designed to conduct protons while acting as an electronic insulator and reactant barrier, e.g. to oxygen and hydrogen gas. This is their essential function when incorporated into a membrane electrode assembly (MEA) of a proton-exchange membrane fuel cell or of a proton-exchange membrane electrolyser: separation of reactants and transport of protons while blocking a direct electronic pathway through the membrane. PEMs can be made from either pure polymer membranes or from composite membranes, where other materials are embedded in a polymer matrix.

The multistep reaction mechanism begins with deprotonation of the alcohol, followed by the oxygen-anion attacking the adjacent trichloromethyl position to form an epoxide. The azide then opens this ring by an SN2 reaction to give a 2-azido structure whose stereochemistry is inverted compared to the original 2-hydroxy. The oxygen, having become attached to the first carbon of the chain during the epoxide formation, simultaneously displaces a second chlorine atom there to form an acyl chloride. An additional nucleophilic reactant, such as hydroxide or an alkoxide, then triggers an acyl substitution there to produce a carboxylic acid or ester.

A PES is a conceptual tool for aiding the analysis of molecular geometry and chemical reaction dynamics. Once the necessary points are evaluated on a PES, the points can be classified according to the first and second derivatives of the energy with respect to position, which respectively are the gradient and the curvature. Stationary points (or points with a zero gradient) have physical meaning: energy minima correspond to physically stable chemical species and saddle points correspond to transition states, the highest energy point on the reaction coordinate (which is the lowest energy pathway connecting a chemical reactant to a chemical product).

Synthese eines substituierten Butenolids mit Diethylmesoxalat With guanidines, a functionalized imidazolone is produced in 85% yield. Synthese von Imidazolonen mit Diethylmesoxalat Diethyl oxomalonate is a versatile reactant in the Baylis-Hillman reaction and forms the corresponding multifunctional compounds with acrylates, acrylonitrile, or methyl vinyl ketone catalysed by DABCO. Baylis–Hillman reaction mit Diethylmesoxalat Diethyl oxomalonate reacts with the Grignard compound formed from 1-iodo-2-chloromethylbenzene and isopropylmagnesium chloride to give 2-bis- carboxyethyl-isobenzofuran. Synthese von Isobenzofuranen mit Diethylmesoxalat Diethyl oxomalonate is added to terminal double bonds of alkenes in an ene reaction to give 1-hydroxy-1-alkylmalonic esters.

Virtually every reaction in a living cell requires an enzyme to lower the activation energy of the reaction. These molecules recognize specific reactant molecules called substrates; they then catalyze the reaction between them. By lowering the activation energy, the enzyme speeds up that reaction by a rate of 1011 or more; a reaction that would normally take over 3,000 years to complete spontaneously might take less than a second with an enzyme. The enzyme itself is not used up in the process and is free to catalyze the same reaction with a new set of substrates.

Since many hydrogenation reactions such as hydrogenolysis of protecting groups and the reduction of aromatic systems proceed extremely sluggishly at atmospheric temperature and pressure, pressurised systems are popular. In these cases, catalyst is added to a solution of reactant under an inert atmosphere in a pressure vessel. Hydrogen is added directly from a cylinder or built in laboratory hydrogen source, and the pressurized slurry is mechanically rocked to provide agitation, or a spinning basket is used. Recent advances in electrolysis techonology have led to the development of high pressure hydrogen generators, which generate hydrogen up to 100 bar (1400 PSI) from water.

A concentration cell produces a small voltage as it attempts to reach chemical equilibrium, which occurs when the concentration of reactant in both half- cells are equal. Because an order of magnitude concentration difference produces less than 60 millivolts at room temperature, concentration cells are not typically used for energy storage. A concentration cell generates electricity from the reduction in the thermodynamic free energy of the electrochemical system as the difference in the chemical concentrations in the two half-cells is reduced. The same reaction occurs in the half-cells but in opposite directions, increasing the lower and decreasing the higher concentration.

The chemical reactions in the cell may involve the electrolyte, the electrodes, or an external substance (as in fuel cells that may use hydrogen gas as a reactant). In a full electrochemical cell, species from one half-cell lose electrons (oxidation) to their electrode while species from the other half-cell gain electrons (reduction) from their electrode. A salt bridge (e.g., filter paper soaked in KNO3, NaCl, or some other electrolyte) is often employed to provide ionic contact between two half-cells with different electrolytes, yet prevent the solutions from mixing and causing unwanted side reactions.

Concerns have also surfaced over the accuracy of the Benesi–Hildebrand method as certain conditions cause these calculations to become invalid. For instance, the reactant concentrations must always obey the assumption that the initial concentration of the guest ([G]0) is much larger than the initial concentration of the host ([H]0). In the case when this breaks down, the Benesi–Hildebrand plot deviates from its linear nature and exhibits scatter plot characteristics. Also, in the case of determining the equilibrium constants for weakly bound complexes, it is common for the formation of 2:1 complexes to occur in solution.

As with other procedures predicated on biochemical alteration followed by sequencing, the development of high-throughput sequencing has removed the limitations requiring prior knowledge of sites of interest and primer design. The method causes a lot of RNA degradation, so it is necessary to start with a large amount of sample, or use effective normalisation techniques to account for amplification biases. One final limitation is that, for CMC labelling of pseudouridine to be specific, it is not complete, and therefore nor is it quantitative. A new reactant that could achieve a higher sensitivity with specificity would be beneficial.

Today hydrogen is mainly used in chemical industry as a reactant in ammonia production and methanol synthesis, and in refinery processes for hydrocracking. Moreover, there is a growing interest in its use as energy carrier and as fuel in fuel cells. More than 50% of hydrogen is currently produced from steam reforming of natural gas, due to low costs and the fact that it is a mature technology. Traditional processes are composed by a steam reforming section, to produce syngas from natural gas, two water gas shift reactors which enhance hydrogen in syngas and a pressure swing adsorption unit for hydrogen purification.

It is used in thermal printers, particularly in inexpensive or lightweight devices such as adding machines, cash registers, and credit card terminals. The surface of the paper is coated with a solid-state mixture of dye and a suitable matrix; a combination of a fluoran leuco dye for example. When the matrix is heated above its melting point, the dye reacts with the acid, shifts to its colored form, and the changed form is then conserved in a metastable state when the matrix solidifies back quickly enough. The reactant acid in thermal paper is often bisphenol A (BPA).

There are two objections to associating this activation energy with the threshold barrier for an elementary reaction. First, it is often unclear as to whether or not reaction does proceed in one step; threshold barriers that are averaged out over all elementary steps have little theoretical value. Second, even if the reaction being studied is elementary, a spectrum of individual collisions contributes to rate constants obtained from bulk ('bulb') experiments involving billions of molecules, with many different reactant collision geometries and angles, different translational and (possibly) vibrational energies—all of which may lead to different microscopic reaction rates.

In this process electrons are effectively introduced at the cathode as a reactant and removed at the anode as a product. In chemistry, the loss of electrons is called oxidation, while electron gain is called reduction. When neutral atoms or molecules, such as those on the surface of an electrode, gain or lose electrons they become ions and may dissolve in the electrolyte and react with other ions. When ions gain or lose electrons and become neutral, they may form compounds that separate from the electrolyte. Positive metal ions like Cu2+ deposit onto the cathode in a layer.

A diagram of this particular synthesis as it applies to the preparation of etonitazene is shown below. 500px A particularly novel, high-yielding synthesis of etonitazene was developed by FI Carroll and MC Coleman in the mid-1970s The authors were tasked with the preparation of large quantities of etonitazene, but found the conventional synthesis to be inadequate. The problem with the conventional synthesis was the lability of the imino ether reactant, 2-(4-Ethoxyphenyl)-acetimidic acid ethyl ester (prepared by reacting 4-ethoxyphenylacetonitrile with ethanolic HCl). The imino ether necessitated the use of anhydrous reaction conditions and was inconvenient to prepare in large quantities.

DOTA linked to the monoclonal antibody tacatuzumab and chelating yttrium-90 Whole-body PET scan using 18F-FDG showing intestinal tumors and non-specific accumulation in bladder Radiolabeling is a technique used to track the passage of a molecule that incorporates a radioisotope through a reaction, metabolic pathway, cell, tissue, organism, or biological system. The reactant is 'labeled' by replacing specific atoms by their isotope. Replacing an atom with its own radioisotope is an intrinsic label that does not alter the structure of the molecule. Alternatively, molecules can be radiolabeled by chemical reactions that introduce an atom, moiety, or functional group that contains a radionuclide.

Whereas transition metals sometimes attract most of the attention in the study of catalysis, small organic molecules without metals can also exhibit catalytic properties, as is apparent from the fact that many enzymes lack transition metals. Typically, organic catalysts require a higher loading (amount of catalyst per unit amount of reactant, expressed in mol% amount of substance) than transition metal(-ion)-based catalysts, but these catalysts are usually commercially available in bulk, helping to reduce costs. In the early 2000s, these organocatalysts were considered "new generation" and are competitive to traditional metal(-ion)-containing catalysts. Organocatalysts are supposed to operate akin to metal-free enzymes utilizing, e.g.

US: Springer. pp. 281–288. Silver carbonate on celite oxidizes alcohols through single electron oxidation by the silver cations Even weakly associating functionalities such as olefins can interfere with the association of the reactant alcohol with Fetizon's reagent The rate limiting step of this reaction is proposed to be the initial association of the alcohol to the silver ions. As a result, the presence of even weakly associating ligands to the silver can inhibit the reaction greatly. As a result, even slightly polar solvents of any variety, such as ethyl acetate or methyl ethyl ketone, are avoided when using this reagent as they competitively associate with the reagent.

Additional polar functionalities of the reactant should also be avoided whenever possible as even the presence of an alkene can sometimes reduce the reactivity of a substrate 50 fold. Commonly employed solvents such as benzene and xylene are extremely non-polar and further acceleration of the reaction can be achieved through the use of the more non-polar heptane. The solvent is also typically refluxed to drive the reaction with heat and remove the water generated by the reaction through azeotropic distillation. Steric hindrance of the hydrogen alpha to the alcohol is a major determination of the rate of oxidation as it effects the rate of association.

As most components of ambient air possess a lower proton affinity than H2O (e.g. N2, O2, Ar, CO2, etc.) the H3O+ ions only react with VOC trace components and the air itself acts as a buffer gas. Moreover, due to the low concentrations of trace components one can assume that the total number of H3O+ ions remains nearly unchanged, which leads to the equation In equation () [RH+] is the density of product ions, [H3O+]0 is the density of reagent ions in absence of reactant molecules in the buffer gas, is the reaction rate constant and is the average time the ions need to pass the reaction region.

Albumin is considered a negative acute phase reactant, which means that as inflammation and other acute physiologic processes occur, its levels decrease. This is in contrast to acute phase reactants like C-reactive protein (CRP), whose levels increase with inflammatory processes. With respect to mechanism, inflammation leads to decreased production of albumin as a result of increased levels of cytokines, specifically IL-1, IL-6, and TNF-α. In patients with the overwhelming infections common in sepsis and septic shock, hypoalbuminemia occurs as a result of the combinatorial effects of decreased synthesis as above, increased utilization by tissues, and increased transcapillary leakage from blood vessels due to increased vascular permeability.

The advantage of a gas phase reaction over a comparable liquid phase process is the control of moisture from the ambient environment, which often results in cross polymerization of the silane leading to particulates on the treated surface. Often a heated sub- atmospheric vacuum chamber is used to allow precise control of the reactants and water content. Additionally the gas phase process allows for easy treatment of complex parts since the coverage of the reactant is generally diffusion limited. Microelectromechanical Systems (MEMS) sensors often use molecular vapor deposition as a technique to address stiction and other parasitic issues relative to surface-to-surface interactions.

This distinction makes sense only when the equilibrium so favors the products to cause the complete consumption of one of the reactants. In studies of reaction kinetics, the rate of progress of the reaction may be limited by the concentration of one of the reactants or catalysts. In multi-step reactions, a step may be rate-limiting in terms of production of the final product. In vivo in an organism or an ecologic system, such factors as those may be rate-limiting, or in the overall analysis of a multi-step process including biologic, geologic, hydrologic, or atmospheric transport and chemical reactions, transport of a reactant may be limiting.

In general terms, the free energy change (ΔG) of a reaction determines whether a chemical change will take place, but kinetics describes how fast the reaction is. A reaction can be very exothermic and have a very positive entropy change but will not happen in practice if the reaction is too slow. If a reactant can produce two products, the thermodynamically most stable one will form in general, except in special circumstances when the reaction is said to be under kinetic reaction control. The Curtin-Hammett principle applies when determining the product ratio for two reactants interconverting rapidly, each going to a distinct product.

Usually this occurs when a molecule becomes ionized, often as the result of an interaction with cosmic rays. This positively charged molecule then draws in a nearby reactant by electrostatic attraction of the neutral molecule's electrons. Molecules can also be generated by reactions between neutral atoms and molecules, although this process is generally slower. The dust plays a critical role of shielding the molecules from the ionizing effect of ultraviolet radiation emitted by stars. Mathematician Jason Guillory in his 2008 analysis of 12C/13C isotopic ratios of organic compounds found in the Murchison meteorite indicates a non-terrestrial origin for these molecules rather than terrestrial contamination.

An alternative mechanism is schiff base formation using the free amine from a lysine residue, as seen in the enzyme aldolase during glycolysis. Some enzymes utilize non-amino acid cofactors such as pyridoxal phosphate (PLP) or thiamine pyrophosphate (TPP) to form covalent intermediates with reactant molecules.Toney, M. D. "Reaction specificity in pyridoxal enzymes." Archives of biochemistry and biophysics (2005) 433: 279-287Micronutrient Information Center, Oregon State University Such covalent intermediates function to reduce the energy of later transition states, similar to how covalent intermediates formed with active site amino acid residues allow stabilization, but the capabilities of cofactors allow enzymes to carryout reactions that amino acid side residues alone could not.

A favorable reaction is one in which the change in free energy ∆G° is negative (exergonic) or in other words, the free energy of product, G°product, is less than the free energy of the starting materials, G°reactant. ∆G°> 0 (endergonic) corresponds to an unfavorable reaction. The ∆G° can be written as a function of change in enthalpy (∆H°) and change in entropy (∆S°) as ∆G°= ∆H° – T∆S°. Practically, enthalpies, not free energy, are used to determine whether a reaction is favorable or unfavorable, because ∆H° is easier to measure and T∆S° is usually too small to be of any significance (for T < 100 °C).

This results in some of the fuel's energy being used to "assist" the electrolysis process and can reduce the overall cost of hydrogen produced. However, observing the entropy component (and other losses), voltages over 1.48 V are required for the reaction to proceed at practical current densities (the thermoneutral voltage). In the case of water electrolysis, Gibbs free energy represents the minimum work necessary for the reaction to proceed, and the reaction enthalpy is the amount of energy (both work and heat) that has to be provided so the reaction products are at the same temperature as the reactant (i.e. standard temperature for the values given above).

Small differences in mass between stable isotopes of the same element can lead to a phenomenon called an "isotope effect," where heavier or lighter isotopes are preferentially incorporated into different natural materials depending on the materials' chemical composition or physical state. Isotope effects are divided into two main groups: kinetic isotope effects and equilibrium isotope effects. A kinetic isotope effect occurs when a reaction is irreversible, meaning that the reaction only proceeds in the direction from reactants to products. Kinetic isotope effects cause isotopic fractionation—meaning that they affect the isotopic composition of reactant and product compounds—because the mass differences between stable isotopes can affect the rate of chemical reactions.

Closed systems containing substances undergoing a reversible chemical reaction can also exhibit negative feedback in accordance with Le Chatelier's principle which shift the chemical equilibrium to the opposite side of the reaction in order to reduce a stress. For example, in the reaction : N2 \+ 3 H2 ⇌ 2 NH3 \+ 92 kJ/mol If a mixture of the reactants and products exists at equilibrium in a sealed container and nitrogen gas is added to this system, then the equilibrium will shift toward the product side in response. If the temperature is raised, then the equilibrium will shift toward the reactant side which, because the reverse reaction is endothermic, will partially reduces the temperature.

The equilibrium constant of a chemical reaction is the value of its reaction quotient at chemical equilibrium, a state approached by a dynamic chemical system after sufficient time has elapsed at which its composition has no measurable tendency towards further change. For a given set of reaction conditions, the equilibrium constant is independent of the initial analytical concentrations of the reactant and product species in the mixture. Thus, given the initial composition of a system, known equilibrium constant values can be used to determine the composition of the system at equilibrium. However, reaction parameters like temperature, solvent, and ionic strength may all influence the value of the equilibrium constant.

Raman spectroscopy is one of the easiest methods to integrate into a heterogeneous operando experiment, as these reactions typically occur in the gas phase, so there is very low litter interference and good data can be obtained for the species on the catalytic surface. In order to use Raman, all that is required is to insert a small probe containing two optical fibers for excitation and detection. Pressure and heat complications are essentially negligible, due to the nature of the probe. Operando confocal Raman micro-spectroscopy has been applied to the study of fuel cell catalytic layers with flowing reactant streams and controlled temperature.

In these models the phase paths can "spiral in" towards zero, "spiral out" towards infinity, or reach neutrally stable situations called centres where the path traced out can be either circular, elliptical, or ovoid, or some variant thereof. This is useful in determining if the dynamics are stable or not. Other examples of oscillatory systems are certain chemical reactions with multiple steps, some of which involve dynamic equilibria rather than reactions that go to completion. In such cases one can model the rise and fall of reactant and product concentration (or mass, or amount of substance) with the correct differential equations and a good understanding of chemical kinetics.

The reaction mechanism varies with reactant and reaction conditions with the fragmentation taking place in a concerted reaction or taking place in two steps with a carbocationic intermediate when the nucleofuge leaves first or taking place in two steps with an anionic intermediate when the electrofuge leaves first. The carbanionic pathway is more common and is facilitated by the stability of the cation formed and the leaving group ability of the nucleofuge. With cyclic substrates, the preferred geometry of elimination is for the sigma bond that drives out the leaving group to being anti to it, analogous to the conformational orientation in the E2 mechanism of elimination reactions.

A crystal of sodium acetate trihydrate (length 1.7 centimetres) For laboratory use, sodium acetate is inexpensive and usually purchased instead of being synthesized. It is sometimes produced in a laboratory experiment by the reaction of acetic acid, commonly in the 5–8% solution known as vinegar, with sodium carbonate ("washing soda"), sodium bicarbonate ("baking soda"), or sodium hydroxide ("lye", or "caustic soda"). Any of these reactions produce sodium acetate and water. When a sodium and carbonate ion-containing compound is used as the reactant, the carbonate anion from sodium bicarbonate or carbonate, reacts with hydrogen from the carboxyl group (-COOH) in acetic acid, forming carbonic acid.

The law was devised by French general Guillaume Piobert in 1839 to explain the behavior of gunpowder, but it has subsequently been applied to other solid propellants. Description of the reaction as burning may cause confusion with simple atmospheric combustion of solid materials where a similar reaction progression may be attributed to availability of the oxygen reactant only at the surface of the solid being consumed by the reaction. In the case of single-phase propellant grains, the progression is attributed to heat transfer from the surface of the solid of energy necessary to initiate the reaction. The heat transfer rate increases with pressure; and smokeless powder reaction rates vary with pressure as described by Paul Vieille in 1893.

When the rate of interconversion between A and B is much faster than either k1 or k2, then the Curtin–Hammett principle tells us that the C:D product ratio is not equal to the equilibrium A:B reactant ratio, but is instead determined by the relative energies of the transition states (i.e., difference in the absolute energies of the transition states). If reactants A and B were at identical energies, the product ratio would depend only on the activation barriers of the reactions leading to each respective product. However, in a real-world scenario, the two reactants are likely at somewhat different energy levels, although the barrier to their interconversion must be low for the Curtin–Hammett scenario to apply.

In 1925, with G.E. Briggs, Haldane derived a new interpretation of the enzyme kinetic law of Victor Henri in 1903, better known as the 1913 Michaelis–Menten equation. Leonor Michaelis and Maud Menten assumed that enzyme (catalyst) and substrate (reactant) are in fast equilibrium with their complex, which then dissociates to yield product and free enzyme. By contrast, at almost the same time, Donald Van Slyke and G. E. Cullen treated the binding step as an irreversible reaction. The Briggs–Haldane equation was of the same algebraic form as both of the earlier equations, but their derivation is based on the quasi-steady state approximation, which is the concentration of intermediate complex (or complexes) does not change.

Crystallography shows that the enzyme is a Class I aldolase, so the mechanism proceeds via the formation of a Schiff base with Lys167 at the active site. A nearby residue, Lys201, is critical to reaction by increasing the acidity of protonated Lys167, so Schiff base formation can occur more readily. As equilibrium of the reaction as written lies on the side of reactant, DERA can also used to catalyze the backward aldol reaction. The enzyme has been found to exhibit some promiscuity by accepting various carbonyl compounds as substrates: acetaldehyde can be replaced with other small aldehydes or acetone; and a variety of aldehydes can be used in place of D-glyceraldehyde 3-phosphate.

Ferritin, a routine investigation for anemia, is an acute-phase reactant, and may be elevated in states of inflammation, thereby falsely indicating that iron stores are adequate. Because sTfR is insensitive to inflammation, it can detect anemia in patients with preexisting inflammatory states, and is particularly useful in distinguishing between the anemia of chronic disease and anemias caused by lack of iron intake. To date, the conventionally identified soluble transferrin receptor has not been itself implicated in intracellular delivery of transferrin and associated iron stores. A soluble receptor for any ligand could also refer to a molecule present is solution (for example a secretory protein) which would bind with the target ligand and then effect cellular delivery.

NMR spectroscopy is often the method of choice for monitoring reaction progress, where substrate consumption and/or product formation may be observed over time from the change of peak integration relative to a non-reactive standard. From the concentration data, the rate of reaction over time may be obtained by taking the derivative of a polynomial fit to the experimental curve. Reaction progress NMR may be classified as an integral technique as the primary data collected are proportional to concentration vs. time. While this technique is extremely convenient for clearly defined systems with distinctive, isolated product and/or reactant peaks, it has the drawback of requiring a homogeneous system amenable to reaction in an NMR tube.

An isodesmic reaction is a chemical reaction in which the type of chemical bonds broken in the reactant are the same as the type of bonds formed in the reaction product. This type of reaction is often used as a hypothetical reaction in thermochemistry. An example of an isodesmic reaction is :CH3− \+ CH3X -> CH4 \+ CH2X− (1) :X = F, Cl, Br, I Equation 1 describes the deprotonation of a methyl halide by a methyl anion. The energy change associated with this exothermic reaction which can be calculated in silico increases going from fluorine to chlorine to bromine and iodine making the CH2I− anion the most stable and least basic of all the halides.

The Nazarov cyclization reaction is a named electrocyclic reaction converting divinylketones to cyclopentenones. A classic example is the thermal ring-opening reaction of 3,4-dimethylcyclobutene. The cis isomer exclusively yields cis,trans-hexa-2,4-diene whereas the trans isomer gives the trans,trans diene:The preparation and isomerization of - and -3,4-dimethylcyclobutene. Tetrahedron Letters, Volume 6, Issue 17, 1965, Pages 1207-1212 Rudolph Ernst K. Winter Dimethylcyclobutene isomerization This reaction course can be explained in a simple analysis through the frontier- orbital method: the sigma bond in the reactant will open in such a way that the resulting p-orbitals will have the same symmetry as the HOMO of the product (a hexadiene).

Hg(C6F5)2 is a better RT reagent to use with lanthanides than HgPh2 because it does not require a step to activate the metal. However, phenyl-substituted lanthanide complexes are more thermally stable than the pentafluorophenyl complexes. The use of HgPh2 led to the synthesis of a ytterbium complex with different oxidation states on the two Yb atoms: :Yb(C10H8)(THF)2 \+ HgPh2 → YbIIYbIIIPh5(THF)4 In the Ln(C6F5)2 complexes, where Ln = Yb, Eu, or Sm, the Ln–C bonds are very reactive, making them useful in RTLE reactions. Protic substrates have been used as a reactant with the Ln(C6F5)2 complex as shown: Ln(C6F5)2 \+ 2LH → Ln(L)2 \+ 2C6F5H.

Jones and others have responded that they do not believe that thermite was used, but rather a form of thermite called nano-thermite, a nanoenergetic material developed for military use, propellants, explosives, or pyrotechnics. Historically, explosive applications for traditional thermites have been limited by their relatively slow energy release rates. But because nano-thermites are created from reactant particles with proximities approaching the atomic scale, energy release rates are far improved. The NIST report provides an analysis of the structural response of the building only up to the point where collapse begins, and asserts that the enormous kinetic energy transferred by the falling part of the building makes progressive collapse inevitable once an initial collapse occurs.

Physical organic chemists use the mathematical foundation of chemical kinetics to study the rates of reactions and reaction mechanisms. Unlike thermodynamics, which is concerned with the relative stabilities of the products and reactants (ΔG°) and their equilibrium concentrations, the study of kinetics focuses on the free energy of activation (ΔG‡) -- the difference in free energy between the reactant structure and the transition state structure—of a reaction, and therefore allows a chemist to study the process of equilibration. Mathematically derived formalisms such as the Hammond Postulate, the Curtin-Hammett principle, and the theory of microscopic reversibility are often applied to organic chemistry. Chemists have also used the principle of thermodynamic versus kinetic control to influence reaction products.

One-pot preparation of 7-Hydroxyquinoline In chemistry a one-pot synthesis is a strategy to improve the efficiency of a chemical reaction whereby a reactant is subjected to successive chemical reactions in just one reactor. This is much desired by chemists because avoiding a lengthy separation process and purification of the intermediate chemical compounds can save time and resources while increasing chemical yield. An example of a one-pot synthesis is the total synthesis of tropinone or the Gassman indole synthesis. Sequential one-pot syntheses can be used to generate even complex targets with multiple stereocentres, such as oseltamivir, which may significantly shorten the number of steps required overall and have important commercial implications.

In chemical kinetics, the overall rate of a reaction is often approximately determined by the slowest step, known as the rate-determining step (RDS) or rate-limiting step. For a given reaction mechanism, the prediction of the corresponding rate equation (for comparison with the experimental rate law) is often simplified by using this approximation of the rate-determining step. In principle, the time evolution of the reactant and product concentrations can be determined from the set of simultaneous rate equations for the individual steps of the mechanism, one for each step. However, the analytical solution of these differential equations is not always easy, and in some cases numerical integration may even be required.

Selective non-catalytic reduction (SNCR) is a method to lessen nitrogen oxide emissions in conventional power plants that burn biomass, waste and coal. The process involves injecting either ammonia or urea into the firebox of the boiler at a location where the flue gas is between to react with the nitrogen oxides formed in the combustion process. The resulting product of the chemical redox reaction is molecular nitrogen (N2), carbon dioxide (CO2), and water (H2O). Urea (NH2CONH2) reacts similarly to and is easier to handle and store than the more dangerous ammonia (NH3), so it is the reactant of choice: :NH2CONH2 \+ H2O -> 2NH3 \+ CO2 The reduction happens according to (simplified):Duo et al., 1992 Can.

When alkenes and alkynes are subjected to hydrogenation reaction by treating them with hydrogen in the presence of palladium or platinum or nickel catalyst, they produce alkanes. In this reaction powdered catalyst is preferred to increase the surface area so that adsorption of hydrogen on the catalyst increases. In this reaction the hydrogen gets attached on the catalyst to form a hydrogen-catalyst bond which leads to weakening of H-H bond, thereby leading to the addition of hydrogen on alkenes and alkynes. The reaction is exothermic because the product alkane is stable as it has more sigma bonds than the reactant alkenes and alkynes due to conversion of pi bond to sigma bonds.Harikiran.

The other helices were not found to host residues critical for catalytic activity, and may serve in structural roles. Mycobacterium tuberculosis bifunctional histidine/tryptophan biosynthesis isomerase (PriA) () possesses the ability to catalyse two reactions: (i) HisA reaction: the conversion of N-[(5-phosphoribosyl) formimino]-5-aminoimidazole-4-carboxamide ribonucleotide (ProFAR) to N-[(5-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamide ribonucleotide (PRFAR), and (ii) TrpF reaction: N-(5’-phosphoribosyl)-anthranilate (PRA) to 1-(O-carboxyphenylamino)- 1’-deoxyribulose-5’-phosphate (CdRP). PriA is a TIM barrel enzyme that accommodates both substrates using active site loops (loops 1, 5, and 6, extended βα loops at the C-terminal end of the β-barrel) that change conformation depending on the reactant present.

Diethyl oxomalonate is the diethyl ester of mesoxalic acid (ketomalonic acid), the simplest oxodicarboxylic acid and thus the first member (n = 0) of a homologous series HOOC–CO–(CH2)n–COOH with the higher homologues oxalacetic acid (n = 1), α-ketoglutaric acid (n = 2) and α-ketoadipic acid (n = 3) (the latter a metabolite of the amino acid lysine). Diethyl oxomalonate reacts because of its highly polarized keto group as electrophile in addition reactions and is a highly active reactant in pericyclic reactions such as the Diels-Alder reactions, cycloadditions or ene reactions. At humid air, mesoxalic acid diethyl ester reacts with water to give diethyl mesoxalate hydrate and the green-yellow oil are spontaneously converted to white crystals.

Such reactions (summarized in formula below) involve the removal of two hydrogen atoms from the reactant (R), in the form of a hydride ion (H−), and a proton (H). The proton is released into solution, while the reductant RH is oxidized and NAD reduced to NADH by transfer of the hydride to the nicotinamide ring. :RH + NAD → NADH + H + R; From the hydride electron pair, one electron is transferred to the positively charged nitrogen of the nicotinamide ring of NAD, and the second hydrogen atom transferred to the C4 carbon atom opposite this nitrogen. The midpoint potential of the NAD/NADH redox pair is −0.32 volts, which makes NADH a strong reducing agent.

An ionic equation is a chemical equation in which electrolytes are written as dissociated ions. Ionic equations are used for single and double displacement reactions that occur in aqueous solutions. For example, in the following precipitation reaction: :CaCl2 + 2AgNO3 -> Ca(NO3)2 + 2 AgCl(v) the full ionic equation is: :Ca^2+ + 2Cl^- + 2Ag+ + 2NO3^- -> Ca^2+ + 2NO3^- + 2AgCl(v) or, with all physical states included: :Ca^2+(aq) + 2Cl^-(aq) + 2Ag+(aq) + 2NO3^{-}(aq) -> Ca^2+(aq) + 2NO3^{-}(aq) + 2AgCl(v) In this reaction, the Ca2+ and the NO3− ions remain in solution and are not part of the reaction. That is, these ions are identical on both the reactant and product side of the chemical equation.

One driver of protein evolution is the optimization of such catalytic activities, although only the most crucial enzymes operate near catalytic efficiency limits, and many enzymes are far from optimal. Important factors in enzyme catalysis include general acid and base catalysis, orbital steering, entropic restriction, orientation effects (i.e. lock and key catalysis), as well as motional effects involving protein dynamics Mechanisms of enzyme catalysis vary, but are all similar in principle to other types of chemical catalysis in that the crucial factor is a reduction of energy barrier(s) separating the reactants from the products. The reduction of activation energy (Ea) increases the fraction of reactant molecules that can overcome this barrier and form the product.

Photoexcitation is the first step in a photochemical process where the reactant is elevated to a state of higher energy, an excited state. The first law of photochemistry, known as the Grotthuss–Draper law (for chemists Theodor Grotthuss and John W. Draper), states that light must be absorbed by a chemical substance in order for a photochemical reaction to take place. According to the second law of photochemistry, known as the Stark-Einstein law (for physicists Johannes Stark and Albert Einstein), for each photon of light absorbed by a chemical system, no more than one molecule is activated for a photochemical reaction, as defined by the quantum yield.Calvert, J. G.; Pitts, J. N. Photochemistry.

In contrast to indirect methanol fuel cells, where methanol is reacted to hydrogen by steam reforming, DMFCs use a methanol solution (usually around 1M, i.e. about 3% in mass) to carry the reactant into the cell; common operating temperatures are in the range 50-120 °C, where high temperatures are usually pressurized. DMFCs themselves are more efficient at high temperatures and pressures, but these conditions end up causing so many losses in the complete system that the advantage is lost;Dohle, H.; Mergel, J. & Stolten, D.: Heat and power management of a direct-methanol-fuel-cell (DMFC) system, Journal of Power Sources, 2002, 111, 268-282. therefore, atmospheric-pressure configurations are currently preferred.

Binding affinity is a measure of dynamic equilibrium of the ratio of on-rate (kon) and off-rate (koff) under specific concentrations of reactants. The affinity constant, Ka, is the inverse of the dissociation constant, Kd. The strength of complex formation in solution is related to the stability constants of complexes, however in case of large biomolecules, such as receptor-ligand pairs, their interaction is also dependent on other structural and thermodynamic properties of reactants plus their orientation and immobilization. There are several methods to investigate protein–protein interactions existing with differences in immobilization of each reactant in 2D or 3D orientation. The measured affinities are stored in public databases, such as the Ki Database and BindingDB.

In contrast, for SOFC function neither inefficient carbon capture from exhaust gases nor air separation is required: the only required interaction of the anode and cathode reactant streams is the transfer of oxygen from cathode side (air) to anode side (fuel). All carbon, excepting the negligible amount in atmospheric air coming in at the cathode, will enter the module with fuel on the anode side, and it must exit the anode as carbon dioxide and carbon monoxide. By designing the SOFC module to keep anode and cathode off-gas streams separated, dilution of that carbon-rich stream with atmospheric nitrogen from the cathode side is avoided, allowing simple and inexpensive carbon dioxide separation and capture downstream.

When using Kröger–Vink notation for both intrinsic and extrinsic defects, it is imperative to keep all masses, sites, and charges balanced in each reaction. If any piece is unbalanced, the reactants and the products do not equal the same entity and therefore all quantities are not conserved as they should be. The first step in this process is determining the correct type of defect and reaction that comes along with it; Schottky and Frenkel defects begin with a null reactant (∅) and produce either cation and anion vacancies (Schottky) or cation/anion vacancies and interstitials (Frenkel). Otherwise, a compound is broken down into its respective cation and anion parts for the process to begin on each lattice.

Considering the reaction of nitrogen gas with hydrogen gas to form ammonia: : ⇌ ΔH = -92kJ mol−1 Note the number of moles of gas on the left-hand side and the number of moles of gas on the right-hand side. When the volume of the system is changed, the partial pressures of the gases change. If we were to decrease pressure by increasing volume, the equilibrium of the above reaction will shift to the left, because the reactant side has a greater number of moles than does the product side. The system tries to counteract the decrease in partial pressure of gas molecules by shifting to the side that exerts greater pressure.

The string method and uses splines connecting the points, , to measure and enforce distance constraints between the points and to calculate the tangent at each point. In each step of an optimization procedure, the points might be moved according to the force acting on them perpendicular to the path, and then, if the equidistance constraint between the points is no-longer satisfied, the points can be redistributed, using the spline representation of the path to generate new vectors with the required spacing. Variations on the string method include the growing string method, in which the guess of the pathway is grown in from the end points (that is the reactant and products) as the optimization progresses.

Laminar flow reactors employ the characteristics of laminar flow to achieve various research purposes. For instance, LFRs can be used to study fluid dynamics in chemical reactions, or they can be utilized to generate special chemical structures such as carbon nanotubes. One feature of the LFR is that the residence time (The time interval during which the chemicals stay in the reactor) of the chemicals in the reactor can be varied by either changing the distance between the reactant input point and the point at which the product/sample is taken, or by adjusting the velocity of the gas/fluid. Therefore the benefit of a laminar flow reactor is that the different factors that may affect a reaction can be easily controlled and adjusted throughout an experiment.

In other cases, the solid reactants do not need to be melted, but instead can react through a solid-state reaction route. In this method the reactants are repeatedly finely ground into a paste, and then heated to a temperature where the ions in neighbouring reactants can diffuse together during the time the reactant mixture remains in the oven. Other synthetic routes use a solid precursor with the correct stoichiometric ratio of non-volatile ions, which is heated to drive off other species. In some reactions between highly reactive metals (usually from Group 1 or Group 2) and highly electronegative halogen gases, or water, the atoms can be ionized by electron transfer, a process thermodynamically understood using the Born–Haber cycle.

Beyond the inner wall of the containment vessel one of several test blanket modules will be placed. These are designed to slow and absorb neutrons in a reliable and efficient manner, limiting damage to the rest of the structure, and breeding tritium for fuel from lithium-bearing ceramic pebbles contained within the blanket module following the following reactions: : + → + : + → + + where the reactant neutron is supplied by the D-T fusion reaction. Energy absorbed from the fast neutrons is extracted and passed into the primary coolant. This heat energy would then be used to power an electricity-generating turbine in a real power station; in ITER this generating system is not of scientific interest, so instead the heat will be extracted and disposed of.

The charge (many elementary charges) may be transferred in any portion from one body to another. # Marcus separates the fast electron polarisation Pe and the slow atom and orientation polarisation Pu of the solvent on grounds of their time constants differing several orders of magnitude. # Marcus separates the inner sphere (reactant + tightly bound solvent molecules, in complexes + ligands) and the outer sphere (free solvent ) # In this model Marcus confines himself to calculating the outer sphere energy of the non-equilibrium polarization of the "transition state". The outer sphere energy is often much larger than the inner sphere contribution because of the far reaching electrostatic forces (compare the Debye-Hückel theory of electrochemistry). Marcus’ tool is the theory of dielectric polarization in solvents.

One cation replaces another. A cation is a positively charged ion or a metal. When it is written in generic symbols, it is written out like this: :X + YZ → XZ + Y Element X has replaced Y in compound YZ to become a new compound XZ and the free element Y. This is an oxidation–reduction reaction wherein element Y is reduced from a cation into the elemental form and element X is oxidized from the elemental form into a cation. Some examples are: # Cu + 2AgNO3 -> 2Ag(v) + Cu(NO3)2 # Fe + Cu(NO3)2 -> Fe(NO3)2 + Cu(v) # Ca + 2H2O -> Ca(OH)2 + H2 (^) # Zn + 2HCl -> ZnCl2 + H2 (^) If the reactant in elemental form is not the more reactive metal, then no reaction will occur.

When attached to certain functional groups in a reactant molecule, trimethylsilyl groups may also be used as temporary protecting groups during chemical synthesis or some other chemical reactions. In chromatography, derivitization of accessible silanol groups in a bonded stationary phase with trimethylsilyl groups is referred to as endcapping. In an NMR spectrum, signals from atoms in trimethylsilyl groups in compounds will commonly have chemical shifts close to the tetramethylsilane reference peak at 0 ppm. Also compounds, such as high temperature silicone "stopcock" grease, which have polysiloxanes (often called silicones) in them will commonly show peaks from their methyl groups (attached to the silicon atoms) having NMR chemical shifts close to the tetramethylsilane standard peak, such as at 0.07 ppm in CDCl3.

Studying them has yielded important insights into reaction mechanisms, enzyme structure and function, catalysis, and the immune system itself. Enzymes function by lowering the activation energy of the transition state of a chemical reaction, thereby enabling the formation of an otherwise less-favorable molecular intermediate between the reactant(s) and the product(s). If an antibody is developed to bind to a molecule that is structurally and electronically similar to the transition state of a given chemical reaction, the developed antibody will bind to, and stabilize, the transition state, just like a natural enzyme, lowering the activation energy of the reaction, and thus catalyzing the reaction. By raising an antibody to bind to a stable transition-state analog, a new and unique type of enzyme is produced.

For a chemical reaction or process an energy profile (or reaction coordinate diagram) is a theoretical representation of a single energetic pathway, along the reaction coordinate, as the reactants are transformed into products. Reaction coordinate diagrams are derived from the corresponding potential energy surface (PES), which are used in computational chemistry to model chemical reactions by relating the energy of a molecule(s) to its structure (within the Born–Oppenheimer approximation). The reaction coordinate is a parametric curve that follows the pathway of a reaction and indicates the progress of a reaction. Figure 1: Reaction Coordinate Diagram: Starting material or reactant A convert to product C via the transition state B. Qualitatively the reaction coordinate diagrams (one-dimensional energy surfaces) have numerous applications.

In very old concrete where the calcium hydroxide has been leached from the leachate seepage path, the chemistry may revert to that similar to "speleothem" chemistry in limestone cave. This is where carbon dioxide enriched rain or seepage water forms a weak carbonic acid, which leaches calcium carbonate (CaCO3) from within the concrete structure and carries it to the underside of the structure. When it contacts the atmosphere, carbon dioxide degasses and calcium carbonate is precipitated to create calthemite deposits, which mimic the shapes and forms of speleothems. This degassing chemistry is not common in concrete structures as the leachate can often find new paths through the concrete to access free calcium hydroxide and this reverts the chemistry to that previously mentioned where CO2 is the reactant.

However, in the case of a chemical rocket, hydrogen is a reactant and reducing agent, not a product. An oxidizing agent, most typically oxygen or an oxygen- rich species, must be introduced into the combustion process, adding mass and chemical bonds to the exhaust species. An additional advantage of light molecules is that they may be accelerated to high velocity at temperatures that can be contained by currently available materials - the high gas temperatures in rocket engines pose serious problems for the engineering of survivable motors. Liquid hydrogen (LH2) and oxygen (LOX, or LO2), are the most effective propellants in terms of exhaust velocity that have been widely used to date, though a few exotic combinations involving boron or liquid ozone are potentially somewhat better in theory if various practical problems could be solved.

Isotope effects are recurring patterns in the partitioning of heavy and light isotopes across different chemical species or compounds, or between atomic sites within a molecule. These isotope effects can come about from a near infinite number of processes, but most of them can be narrowed down into two main categories, based on the nature of the chemical reaction creating or destroying the compound of interest: (1) Kinetic isotope effects manifest in irreversible reactions, when one isotopologue is preferred in the transition state due to the lowest energy state. The preferred isotopologue will depend on whether the transition state of the molecule during a chemical reaction is more like the reactant or the product. Normal isotope effects are defined as those which partition the lighter isotope into the products of the reaction.

In 2008, professor Jeremy P. Meyers, in the Electrochemical Society journal Interface wrote, "While fuel cells are efficient relative to combustion engines, they are not as efficient as batteries, due primarily to the inefficiency of the oxygen reduction reaction. ... [T]hey make the most sense for operation disconnected from the grid, or when fuel can be provided continuously. For applications that require frequent and relatively rapid start-ups ... where zero emissions are a requirement, as in enclosed spaces such as warehouses, and where hydrogen is considered an acceptable reactant, a [PEM fuel cell] is becoming an increasingly attractive choice [if exchanging batteries is inconvenient]". The practical cost of fuel cells for cars will remain high, however, until production volumes incorporate economies of scale and a well-developed supply chain.

Daniel Thomas Gillespie (15 August 1938 – 19 April 2017) was a physicist who is best known for his derivation in 1976 of the stochastic simulation algorithm (SSA), also called the Gillespie algorithm. The SSA is a procedure for numerically simulating the time evolution of the molecular populations in a chemically reacting system in a way that takes account of the fact that molecules react in whole numbers and in a largely random way. Since the late 1990s, the SSA has been widely used to simulate chemical reactions inside living cells, where the small molecular populations of some reactant species often invalidate the differential equations of traditional deterministic chemical kinetics. Gillespie's original derivation of the SSA began by considering how chemical reactions actually occur in a well-stirred dilute gas.

Loss of acetic acid then gives the sigma-allyl C,O-benzoate complex 4, which quickly equilibrates to the pi-allyl haptomer 5. Catalytic cycle 1-2 Coordination of the aldehyde to the iridium results in the formation of a closed chair-like transition state with the allyl moiety, followed by generation of the homoallyl iridium alkoxide 6. This species is presumed to be stable due to coordination of the double bond with the metal, disabling beta- hydride elimination. Exchange of the homoallyl alcohol with another molecule of the reactant alcohol or with another alcohol (isopropanol, or an alcohol that can act as a terminal reductant and turn over the catalytic cycle) opens a coordination site on the iridium (7) and allows for beta-hydride elimination, giving 8 and turning over the catalytic cycle.

The term stereospecific reaction is ambiguous, since the term reaction itself can mean a single- mechanism transformation (such as the Diels–Alder reaction), which could be stereospecific, or the outcome of a reactant mixture that may proceed through multiple competing mechanisms, specific and non-specific. In the latter sense, the term stereospecific reaction is commonly misused to mean highly stereoselective reaction. Chiral synthesis is built on a combination of stereospecific transformations (for the interconversion of existing stereocenters) and stereoselective ones (for the creation of new stereocenters), where also the optical activity of a chemical compound is preserved. The quality of stereospecificity is focused on the reactants and their stereochemistry; it is concerned with the products too, but only as they provide evidence of a difference in behavior between reactants.

The saddle point represents the highest energy point lying on the reaction coordinate connecting the reactant and product; this is known as the transition state. A reaction coordinate diagram may also have one or more transient intermediates which are shown by high energy wells connected via a transition state peak. Any chemical structure that lasts longer than the time for typical bond vibrations (10−13 – 10−14s) can be considered as intermediate. Figure 5:Potential Energy Surface and Corresponding 2-D Reaction Coordinate Diagram derived from the plane passing through the minimum energy pathway between A and C and passing through B A reaction involving more than one elementary step has one or more intermediates being formed which, in turn, means there is more than one energy barrier to overcome.

An electrode typically consists of carbon support, Pt particles, Nafion ionomer, and/or Teflon binder. The carbon support functions as an electrical conductor; the Pt particles are reaction sites; the ionomer provides paths for proton conduction, and the Teflon binder increases the hydrophobicity of the electrode to minimize potential flooding. In order to enable the electrochemical reactions at the electrodes, protons, electrons and the reactant gases (hydrogen or oxygen) must gain access to the surface of the catalyst in the electrodes, while the product water, which can be in either liquid or gaseous phase, or both phases, must be able to permeate from the catalyst to the gas outlet. These properties are typically realized by porous composites of polymer electrolyte binder (ionomer) and catalyst nanoparticles supported on carbon particles.

Ethyl acrylate is used in the production of polymers including resins, plastics, rubber, and denture material.Ethyl acrylate Hazardous Substance Fact Sheet, New Jersey Department of Health and Senior Services Ethyl acrylate is a reactant for homologous alkyl acrylates (acrylic esters) by transesterification with higher alcohols through acidic or basic catalysis. In that way speciality acrylates are made accessible, e.g. 2-ethylhexyl acrylate (from 2-ethylhexanol) used for pressure-sensitive adhesives, cyclohexyl acrylate (from cyclohexanol) used for automotive clear lacquers, 2-hydroxyethyl acrylate (from ethylene glycol) which is crosslinkable with diisocyanates to form gels used with long-chain acrylates (from C18+ alcohols) as comonomer for comb polymers for reduction of the solidification point of paraffin oils and 2-dimethylaminoethyl acrylate (from dimethylaminoethanol) for the preparation of flocculants for sewage clarification and paper production.

The reversible reaction N2O4(g) ⇌ 2NO2(g) is endothermic, so the equilibrium position can be shifted by changing the temperature. When heat is added and the temperature increases, the reaction shifts to the right and the flask turns reddish brown due to an increase in NO2. This demonstrates Le Chatelier's principle: the equilibrium shifts in the direction that consumes energy. When heat is removed and the temperature decreases, the reaction shifts to the left and the flask turns colorless due to an increase in N2O4: again, according to Le Chatelier's principle. The effect of changing the temperature in the equilibrium can be made clear by 1) incorporating heat as either a reactant or a product, and 2) assuming that an increase in temperature increases the heat content of a system.

Three other efficient methods can be used involving continuous operation of mechanical equipment: chemical reactant like calcium nitrate can be continuously added in the sewerage water to impair the H2S formation, an active ventilation through odor treatment units to remove H2S, or an injection of compressed air in pressurized mains to avoid the anaerobic condition to develop. In sewerage areas where biogenic sulfide corrosion is expected, acid resistant materials like calcium aluminate cements, PVC or vitrified clay pipe may be substituted to ordinary concrete or steel sewers. Existing structures that have extensive exposure to biogenic corrosion such as sewer manholes and pump station wet wells can be rehabilitated. Rehabilitation can be done with materials such as a structural epoxy coating, this epoxy is designed to be both acid resistant and strengthen the compromised concrete structure.

Professor Jeremy P. Meyers, in the Electrochemical Society journal Interface in 2008, wrote, "While fuel cells are efficient relative to combustion engines, they are not as efficient as batteries, due primarily to the inefficiency of the oxygen reduction reaction (and ... the oxygen evolution reaction, should the hydrogen be formed by electrolysis of water).... [T]hey make the most sense for operation disconnected from the grid, or when fuel can be provided continuously. For applications that require frequent and relatively rapid start-ups ... where zero emissions are a requirement, as in enclosed spaces such as warehouses, and where hydrogen is considered an acceptable reactant, a [PEM fuel cell] is becoming an increasingly attractive choice [if exchanging batteries is inconvenient]".Meyers, Jeremy P. "Getting Back Into Gear: Fuel Cell Development After the Hype". The Electrochemical Society Interface, Winter 2008, pp.

When an isosbestic plot is constructed by the superposition of the absorption spectra of two species (whether by using molar absorptivity for the representation, or by using absorbance and keeping the same molar concentration for both species), the isosbestic point corresponds to a wavelength at which these spectra cross each other. A pair of substances can have several isosbestic points in their spectra. When a 1-to-1 (one mole of reactant gives one mole of product) chemical reaction (including equilibria) involves a pair of substances with an isosbestic point, the absorbance of the reaction mixture at this wavelength remains invariant, regardless of the extent of reaction (or the position of the chemical equilibrium). This occurs because the two substances absorb light of that specific wavelength to the same extent, and the analytical concentration remains constant.

The objective of the project is the proof of concept of a highly efficient Power-to-Gas technology by thermally integrating high temperature electrolysis (SOEC technology) with CO2-methanation. Through the thermal integration of exothermal methanation and steam generation for the high temperature steam electrolysis conversion efficiency > 85% (higher heating value of produced methane per used electrical energy) are theoretically possible. The process consists of a pressurized high-temperature steam electrolysis and a pressurized CO2-methanation module. The project was completed in 2017 and achieved an efficiency of 76% for the prototype with an indicated growth potential of 80% for industrial scale plants. The operating conditions of the CO2-methanation are a gas pressure of 10 - 30 bar, a SNG production of 1 - 5.4 m3/h (NTP) and a reactant conversion that produces SNG with H2 < 2 vol.

From the above thermodynamic construct, EMC Activation results in a highly amorphous phase that can be justified as a large \Delta H_A and also a large \Delta H_d increase. The benefits of the EMC Activation being large in H means that an EMC's reactivity is less temperature dependent. In terms of any reaction's thermodynamic impetus, a reactant's overall H is not T dependent, meaning that a material having undergone HEBM with a corresponding elevation of H can react at a lower temperature (as the "activated" reactant is rendered less reliant on the temperature-dependent function T \Delta S for its onward progression). Further, an EMC's reaction can exhibit physical mechanisms at extremely small scales "with the formation of thin SiO2 layers" to aid a reaction's pathway—with the suggestion that EMC Activation increases the ratio of favourable reaction sites.

As an extension of the fluidized bed family of separation processes, the flash reactor (FR) (or transport reactor) employs turbulent fluid introduced at high velocities to encourage chemical reactions with feeds and subsequently achieve separation through the chemical conversion of desired substances to different phases and streams. A flash reactor consists of a main reaction chamber and an outlet for separated products to enter downstream processes. FR vessels facilitate a low gas and solid retention (and hence reactant contact time) for industrial applications which give rise to a high throughput, pure product and less than ideal thermal distribution when compared to other fluidized bed reactors. Due to these properties as well as its relative simplicity FRs have the potential for use for pre-treatment and post-treatment processes where these strengths of the FR are prioritized the most.

When the reaction is exothermic (ΔH is negative and energy is released), heat is included as a product, and when the reaction is endothermic (ΔH is positive and energy is consumed), heat is included as a reactant. Hence, whether increasing or decreasing the temperature would favor the forward or the reverse reaction can be determined by applying the same principle as with concentration changes. Take, for example, the reversible reaction of nitrogen gas with hydrogen gas to form ammonia: :N2(g) + 3 H2(g) ⇌ 2 NH3(g) ΔH = -92 kJ mol−1 Because this reaction is exothermic, it produces heat: :N2(g) + 3 H2(g) ⇌ 2 NH3(g) + heat If the temperature were increased, the heat content of the system would increase, so the system would consume some of that heat by shifting the equilibrium to the left, thereby producing less ammonia.

However, the extremely rapid heating rates can result in incomplete reactions between Zr and B, the formation of stable oxides of Zr, and the retention of porosity. Stoichiometric reactions have also been carried out by reaction of attrition milled (wearing materials by grinding) Zr and B powder (and then hot pressing at 600 °C for 6 h), and nanoscale particles have been obtained by reacting attrition milled Zr and B precursor crystallites (10 nm in size). Reduction of ZrO2 and HfO2 to their respective diborides can also be achieved via metallothermic reduction. Inexpensive precursor materials are used and reacted according to the reaction below: ZrO2 \+ B2O3 \+ 5Mg → ZrB2 \+ 5MgO Mg is used as a reactant in order to allow for acid leaching of unwanted oxide products. Stoichiometric excesses of Mg and B2O3 are often required during metallothermic reductions in order to consume all available ZrO2.

For the chemical reaction, A ----> P We can write ( –rA) = k (CA)n (8) (rA) = – k (CA)n (9) Where, ( –rA) = rate of disappearance of A (rA) = rate of formation of A k = reaction rate constant CA = Concentration of reactant A n = order of reaction with respect to component A For first order reaction, n = 1 and accordingly, –rA = k CA The reaction kinetics involved in biochemical operations is comparatively difficult to obtain than the chemical reaction kinetics. In biochemical operations, the cell kinetics is used for the unstructured models where balanced growth condition is assumed. The following equation is used to represent the net rate of cell mass growth: r1 = μx (10) where μ is the specific growth rate or specific growth rate coefficient(s−1). Here, μ is analogous to first order rate constant k but however, μ is not a constant.

It is possible that labeling at one position could distinguish between only two of several possible mechanisms, while placing the isotopic label at a different position could distinguish between three potential mechanisms or provide insight into transition states or intermediates, etc. After the interpretational value is established it is relevant to consider the practical aspects, such as whether or not the synthesis of the proposed reactant is possible, and how easy or difficult it is to distinguish the predicted products for each proposed mechanism and starting materials. For the Claisen rearrangement, labeling by addition of a single methyl group produces an under-labeled system. The resulting crossover experiment would not be useful as a mechanistic study since the products of an intermolecular or intramolecular mechanism are identical. center To have a sufficiently labeled system, both “halves” of the molecule that would separate in an intermolecular mechanism must be labeled.

A secondary kinetic isotope effect is observed when no bond to the isotopically-labeled atom in the reactant is broken or formed. Secondary kinetic isotope effects tend to be much smaller than primary kinetic isotope effects; however, secondary deuterium isotope effects can be as large as 1.4 per deuterium atom, and techniques have been developed to measure heavy-element isotope effects to very high precision, so secondary kinetic isotope effects are still very useful for elucidating reaction mechanisms. For the aforementioned nucleophilic substitution reactions, secondary hydrogen kinetic isotope effects at the α-carbon provide a direct means to distinguish between SN1 and SN2 reactions. It has been found that SN1 reactions typically lead to large secondary kinetic isotope effects, approaching to their theoretical maximum at about 1.22, while SN2 reactions typically yield primary kinetic isotope effects that are very close to or less than unity.

If the chemical system is at low pressure, this enables scientists to observe the energy distribution of the products of a chemical reaction before the differences in energy have been smeared out and averaged by repeated collisions. The absorption of a photon of light by a reactant molecule may also permit a reaction to occur not just by bringing the molecule to the necessary activation energy, but also by changing the symmetry of the molecule's electronic configuration, enabling an otherwise inaccessible reaction path, as described by the Woodward–Hoffmann selection rules. A 2+2 cycloaddition reaction is one example of a pericyclic reaction that can be analyzed using these rules or by the related frontier molecular orbital theory. Some photochemical reactions are several orders of magnitude faster than thermal reactions; reactions as fast as 10−9 seconds and associated processes as fast as 10−15 seconds are often observed.

Trifluoroperacetic acid can be easily prepared by an Organic Syntheses process of treating trifluoroacetic anhydride with a concentrated (90%) aqueous solution of hydrogen peroxide: : \+ -> \+ As the anhydride will form trifluoroacetic acid in contact with water, an excess of the anhydride also serves to remove the solvent from the peroxide reactant: : \+ -> 2 A more dilute hydrogen peroxide solution (30%) can be used to form trifluoroperacetic acid for some reactions from trifluoroacetic acid. : \+ -> \+ In order to avoid the danger of handling pure or highly concentrated solutions of hydrogen peroxide, hydrogen peroxide – urea can be used to give the peracid. This method involves no water, so it gives a completely anhydrous peracid, which is an advantage when the presence of water leads to side reactions during certain oxidation reactions. : \+ -> \+ \+ In cases where a pH buffering agent is needed for a synthesis and where the presence of water is tolerated, another approach has been developed.

Absorption of radiation by reactants of a reaction at equilibrium increases the rate of forward reaction without directly affecting the rate of the reverse reaction. The rate of a photochemical reaction is proportional to the absorption cross section of the reactant with respect to the excitation source (σ), the quantum yield of reaction (Φ), and the intensity of the irradiation. In a reversible photochemical reaction between compounds A and B, there will therefore be a "forwards" reaction of A→B at a rate proportional to σa × ΦA→B and a "backwards" reaction of B→A at a rate proportional to σb × ΦB→A. The ratio of the rates of the forward and backwards reactions determines where the equilibrium lies, and thus the photostationary state is found at: σa × ΦA→B / σb × ΦB→A If (as is always the case to some extent) the compounds A and B have different absorption spectra, then there may exist wavelengths of light where σa is high and σb is low.

In this case, the terminal carbon is a reactant that produces a primary addition product instead of a secondary addition product, in the case of propene. A new method of anti-Markovnikov addition has been described by Hamilton and Nicewicz, who utilize aromatic molecules and light energy from a low-energy diode to turn the alkene into a cation radical. Anti-Markovnikov behaviour extends to more chemical reactions than additions to alkenes. Anti- Markovnikov behaviour is observed in the hydration of phenylacetylene by auric catalysis, which gives acetophenone; although with a special ruthenium catalystcatalyst system based on in-situ reaction of ruthenocene with Cp and naphthalene ligands and a second bulky pyridine ligand it provides the other regioisomer 2-phenylacetaldehyde: Anti-Markovnikov hydration Anti-Markovnikov behavior can also manifest itself in certain rearrangement reactions. In a titanium(IV) chloride-catalyzed formal nucleophilic substitution at enantiopure 1 in the scheme below, two products are formed – 2a and 2b.

Reactions are known where the deuterated species reacts faster than the undeuterated analogue, and these cases are said to exhibit inverse kinetic isotope effects (IKIE). IKIE's are often observed in the reductive elimination of alkyl metal hydrides, e.g. (Me2NCH2CH2NMe2)PtMe(H). In such cases the C-D bond in the transition state, an agostic species, is highly stabilized relative to the C–H bond. An inverse effect can also occur in a multistep reaction if the overall rate constant depends on a pre- equilibria prior to the rate-determining step which has an inverse equilibrium isotope effect. For example, the rates of acid-catalyzed reactions are usually 2-3 times greater for reactions in D2O catalyzed by D3O+ than for the analogous reactions in H2O catalyzed by H3O+ This can be explained for a mechanism of specific hydrogen-ion catalysis of a reactant R by H3O+ (or D3O+). :H3O+ \+ R RH+ \+ H2O :RH+ \+ H2O → H3O+ \+ P The rate of formation of products is then d[P]/dt = k2[RH+] = k2K1[H3O+][R] = kobs[H3O+][R].

Photosynthesis and cellular respiration are distinct processes, as they take place through different sequences of chemical reactions and in different cellular compartments. The general equation for photosynthesis as first proposed by Cornelis van Niel is therefore: : + + → + + Since water is used as the electron donor in oxygenic photosynthesis, the equation for this process is: : + + → + + This equation emphasizes that water is both a reactant in the light-dependent reaction and a product of the light-independent reaction, but canceling n water molecules from each side gives the net equation: : + + → + Other processes substitute other compounds (such as arsenite) for water in the electron-supply role; for example some microbes use sunlight to oxidize arsenite to arsenate:Anaerobic Photosynthesis, Chemical & Engineering News, 86, 33, August 18, 2008, p. 36 The equation for this reaction is: : + + → + (used to build other compounds in subsequent reactions) Photosynthesis occurs in two stages. In the first stage, light-dependent reactions or light reactions capture the energy of light and use it to make the energy-storage molecules ATP and NADPH.

When the beetle feels threatened it opens a valve which allows the aqueous solution from the reservoir to reach the vestibule. The catalases lining the vestibule wall facilitate the decomposition of hydrogen peroxide, as in the following theoretical reaction: :H2O2(aq) -> H2O(l) + 1/2O2(g) The peroxidase enzymes facilitate the oxidation of the hydroquinones into quinones (benzene-1,4-diol into 1,4-benzoquinone and analogously for methylhydroquinone), as in the following theoretical reaction: :C6H4(OH)2(aq) -> C6H4O2(aq) + H2(g) The known net reaction, which further accounts for the theoretical reaction of the H2(g) and 1/2O2(g) products of the previous reactions, is: :C6H4(OH)2(aq) + H2O2(aq) -> C6H4O2(aq) + 2H2O(l) Benzoquinone This reaction is very exothermic, and the released energy raises the temperature of the mixture to near 100 °C, vaporizing about a fifth of it. The resultant pressure buildup forces the entrance valves from the reactant storage chambers to close, thus protecting the beetle's internal organs. The boiling, foul-smelling liquid is expelled violently through an outlet valve, with a loud popping sound.

NbB2 can be synthesized by stoichiometric reaction between constituent elements, in this case Nb and B. This reaction provides for precise stoichiometric control of the materials. Reduction of Nb2O5 (or NbO2) to niobium diboride can also be achieved via metallothermic reduction. Inexpensive precursor materials are used and reacted according to the reaction below: Nb2O5 \+ 2 B2O3 \+ 11 Mg → 2 NbB2 \+ 11 MgO Mg is used as a reactant in order to allow for acid leaching of unwanted oxide products. Stoichiometric excesses of Mg and B2O3 are often required during metallothermic reductions in order to consume all available niobium oxide. Borothermal reduction of NbO2 with elemental boron via solid‐state reaction was proposed by Jha and coworker to obtain nanorods (40 × 800 nm2), A variation of the borothermal reduction in molten salt was proposed by Ran and co‐worker using Nb2O5 with elemental boron to produce nanocrystals (61 nm). Nanocrystals of NbB2 were successfully synthesized by Zoli's reaction, a reduction of Nb2O5 with NaBH4 using a molar ratio M:B of 1:4 at 700 °C for 30 min under argon flow.

Using this value, the potential for any other weight of explosive may be determined by simple proportion. Using the principle of the initial and final state, and heat of formation table (resulting from experimental data), the heat released at constant pressure may be readily calculated. :m n :Qmp = viQfi \- vkQfk :1 1 where: :Qfi = heat of formation of product i at constant pressure :Qfk = heat of formation of reactant k at constant pressure :v = number of moles of each product/reactants (m is the number of products and n the number of reactants) The work energy expended by the gaseous products of detonation is expressed by: :W = P dv With pressure constant and negligible initial volume, this expression reduces to: :W = P·V2 Since heats of formation are calculated for standard atmospheric pressure (101 325 Pa, where 1 Pa = 1 N/m²) and 15°C, V2 is the volume occupied by the product gases under these conditions. At this point :W/mol = (101 325 N/m²)(23.63 l/mol)(1 m³/1000 l) = 2394 N·m/mol = 2394 J/mol and by applying the appropriate conversion factors, work can be converted to units of kilocalories.

STP, a reaction between three cubic meters of hydrogen gas and one cubic meter of nitrogen gas will produce about two cubic meters of ammonia. The law of combining volumes states that, when gases react together they do so in volume which bears simple whole number ratio provided that the temperature and pressure of the reacting gases and their products remain constant The ratio between the volumes of the reactant gases and the gaseous products can be expressed in simple whole numbers. For example, Gay-Lussac found that two volumes of hydrogen and one volume of oxygen would react to form two volumes of gaseous water. Based on Gay-Lussac's results, Amedeo Avogadro hypothesized that, at the same temperature and pressure, equal volumes of gas contain equal numbers of molecules (Avogadro's law). This hypothesis meant that the previously stated result :2 volumes of hydrogen + 1 volume of oxygen = 2 volume of gaseous water could also be expressed as :2 molecules of hydrogen + 1 molecule of oxygen = 2 molecule of water. It can also be expressed in another way of example, 100 mL of hydrogen combine with 50 mL of oxygen to give 100 mL of water vapour.

Soon thereafter, Linus Pauling proposed that the powerful catalytic action of enzymes could be explained by specific tight binding to the transition state species Because reaction rate is proportional to the fraction of the reactant in the transition state complex, the enzyme was proposed to increase the concentration of the reactive species. This proposal was formalized by Wolfenden and coworkers at University of North Carolina at Chapel Hill, who hypothesized that the rate increase imposed by enzymes is proportional to the affinity of the enzyme for the transition state structure relative to the Michaelis complex. Because enzymes typically increase the non-catalyzed reaction rate by factors of 1010-1015, and Michaelis complexes often have dissociation constants in the range of 10−3-10−6 M, it is proposed that transition state complexes are bound with dissociation constants in the range of 10−14 -10−23 M. As substrate progresses from the Michaelis complex to product, chemistry occurs by enzyme-induced changes in electron distribution in the substrate. Enzymes alter the electronic structure by protonation, proton abstraction, electron transfer, geometric distortion, hydrophobic partitioning, and interaction with Lewis acids and bases.

Consider the example burning of magnesium ribbon (Mg). When magnesium burns, it combines with oxygen (O2) from the air to form magnesium oxide (MgO) according to the following equation: :2Mg(s) + O2(g) → 2MgO(s) Magnesium oxide is an ionic compound containing Mg2+ and O2− ions whereas Mg(s) and O2(g) are elements with no charges. The Mg(s) with zero charge gains a +2 charge going from the reactant side to product side, and the O2(g) with zero charge gains a -2 charge. This is because when Mg(s) becomes Mg2+, it loses 2 electrons. Since there are 2 Mg on left side, a total of 4 electrons are lost according to the following oxidation half reaction: :2Mg(s) → 2Mg2+ \+ 4e− On the other hand, O2 was reduced: its oxidation state goes from 0 to -2. Thus, a reduction half reaction can be written for the O2 as it gains 4 electrons: :O2(g) + 4e− → 2O2− The overall reaction is the sum of both half reactions: :2Mg(s) + O2(g) + 4e− →2Mg2+ \+ 2O2− \+ 4e− When chemical reaction, especially, redox reaction takes place, we do not see the electrons as they appear and disappear during the course of the reaction.