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Diethyl 2,3-dihydro-thieno[3,4-b]-1,4-dioxine-5,7-dicarboxyl-ate
Abstract:
The title compound, C(12)H(14)O(6)S, is a dicarboxylic acid diethyl ester of 3,4-ethyl-enedioxy-thio-phene, which is a component of electrically conductive poly(3,4-ethyl-enedioxy-thio-phene) (PEDOT). The ethyl-ene group is disordered over two sites with occupancy factors 0.64 and 0.36. Both the carbonyl groups are coplanar with the thio-phene ring. The mol-ecules form centrosymmetric dimers with an R(2) (2)(12) coupling by inter-molecular C-H⋯O hydrogen bonds [3.333 (5) Å] at the ethoxy-carbonyl groups. The dimer units are arranged to form a ribbon-like mol-ecular sheet.
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Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...
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The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
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