In this sense the figure of coarctate pup is extremely various.
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The most well-known example of a coarctate transition state is that of the epoxidation of an olefin by dimethyldioxirane.Formally, the "butterfly mechanism" of peracid epoxidation is also coarctate. However, the 1s orbital associated with the hydrogen atom cannot undergo productive overlap as a result of its symmetry (see Herges, 2015). Therefore, the orbital symmetry rules developed for coarctate reactions do not apply.
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Formally, the epoxidation of alkenes with peracids can also be considered a coarctate reaction.
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The coarctate is immobile and strongly sclerotized, and it has reduced mouthparts, legs, and musculature.
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The coarctate or pseudopupal stages are those in which hibernation or diapause occurs most frequently.
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Examples of linear, pericyclic, and coarctate transition states In the classification of organic reactions by transition state topology, a coarctate reaction (from L. coarctare "to constrict") is a third, comparatively uncommon topology, after linear topology and pericyclic topology (itself subdivided into Hückel and Möbius topologies).
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Exarate pupae have their legs and other appendages free and extended. Coarctate pupae develop inside the larval skin.
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Since the pupal case is formed by the larval skin, the pupa within is said to be coarctate.
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The wild perennial grass species Porteresia coarctate Tateoka formerly O. coarctata Roxb. is considered as a potential source of genes for salinity tolerance.
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Having cilia. Cilium (plural cilia). A lash; used to designate the hairs on the mantle, gills, etc. Clavate. Club-shaped. Coarctate. Pressed together, narrowed. Concave.
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Herbs like Sesuvium portulacastrum, Suaeda maritima, Suaeda monoica and Salicornia brachiatta and grasses like Aeluropus lagopoides, Porteresia coarctate and Myriostachya wightiana are found in the sanctuary.
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Coarctate pupae develop inside the larval skin. Insects undergo considerable change in form during the pupal stage, and emerge as adults. Butterflies are a well-known example of insects that undergo complete metamorphosis, although most insects use this life cycle. Some insects have evolved this system to hypermetamorphosis.
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Some insects undergo diapause as pupa. In this stage, the insect's physiology and functional structure, both internal and external, change drastically. Pupae can be classified into three types: obtect, exarate, and coarctate. Obtect pupae are compact, with the legs and other appendages enclosed, such as a butterfly chrysalis.
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The larva grows and eventually becomes a pupa, a stage marked by reduced movement and often sealed within a cocoon. There are three types of pupae: obtect, exarate or coarctate. Obtect pupae are compact, with the legs and other appendages enclosed. Exarate pupae have their legs and other appendages free and extended.
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Reactions of linear topology are the most common, and consist of all transformations whose transition states are acyclic, including addition, elimination, substitution, and (some types of) fragmentation reactions. In contrast, in pericyclic reactions, the atoms under chemical change form a closed cycle, and include reactions like the Diels-Alder reaction and Cope rearrangement, among many others. In contrast to these types of reactions, a coarctate reaction is characterized by a doubly cyclic transition state, in which at least one atom undergoes the simultaneous making and breaking of two bonds. Thus, the topology of the transition state of a coarctate reaction is a constricted cycle that meets with itself (resembling a figure eight) while the topology of pericyclic and linear reactions are a circle (or Möbius strip) and line segment, respectively.
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The pupae take various forms. In some groups, particularly the Nematocera, the pupa is intermediate between the larval and adult form; these pupae are described as "obtect", having the future appendages visible as structures that adhere to the pupal body. The outer surface of the pupa may be leathery and bear spines, respiratory features or locomotory paddles. In other groups, described as "coarctate", the appendages are not visible.
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The reaction is considered to be concerted (the numbers in the mechanism below are for simplification). The butterfly mechanism allows ideal positioning of the O-O sigma star orbital for C-C Pi electrons to attack. Because two bonds are broken and formed to the epoxide oxygen, this is formally an example of a coarctate transition state. :Butterfly Mechanism Hydroperoxides are also employed in catalytic enantioselective epoxidations, such as the Sharpless epoxidation and the Jacobsen epoxidation.
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