Process for producing 3,4-enedioxy thiophene

Abstract

The invention provides a method for preparing 3, 4-ethylenedioxythiophene (EDOT for short). Firstly, thiodiglycolic acid and methanol generate dimethyl 2, 2'-thiobisacetate through an esterification reaction under the catalysis of an acid, and then the dimethyl 2, 2'-thiobisacetate is condensed with diethy-aceto oxalate under the catalysis of sodium methoxide to obtain 2, 5-dimethyl carboxylate-3, 4-dihydroxy-thiophene; then the 2, 5-dimethyl carboxylate-3, 4-dihydroxy-thiophene and a cyclic esterification reagent are cyclic-esterified to generate 2, 5-dimethyl carboxylate-3, 4-ethylenedioxythiophene under the cocatalysis of copper powder or cuprous oxide and potassium carbonate, and 2, 5-dicarboxylic acid-3, 4-ethylenedioxythiophene is obtained through alkaline saponification and acid regulation; and finally a copper catalyst remained in the cyclic esterification reaction is used for catalytic decarboxylation in specific pyridine solvents, and the high-purity EDOT is obtained throughreduced pressure distillation. The method has higher yield in the preparation of the EDOT, has low impurity content, and meets the requirement of electronic chemicals.

Description

technical field [0001] The invention relates to a preparation method of 3,4-ethylenedioxythiophene (hereinafter referred to as EDOT), which is a monomer of conductive polymer polyethylenedioxythiophene (PEDOT). Background technique [0002] Polyethylenedioxythiophene is a new type of conductive polymer, which was first synthesized by German Bayer company in 1991. It has the advantages of high conductivity, good environmental stability, easy film production and good transparency. It is used in antistatic packaging , Preparation of organic light-emitting diodes, preparation of organic solar cells, electrochemical capacitors and other fields have important applications, and are expected to be used as superconducting materials and information storage materials in the field of plastic electronic chip devices. Therefore, polyethylenedioxythiophene has become the focus in the field of conducting polymer research. Therefore, developing a suitable synthetic process to produce EDOT (...

AI Technical Summary

Problems solved by technology

[0021] The EDOT process reported in the current literature using thiodiglycolic acid as the starting material has the weakness of low yields in cycloetherification and decarboxylation reactions.

Especially for the decarboxylation reaction, if the solvents reported in the literature are used, the following problems generally exist: the color of the obtained EDOT product is dark, the peculiar smell is heavy (often with a smell different from the smell of EDOT), the residual solvent content is high, and the single impurity High content, low storage stability, etc., so it cannot meet the requirements of EDOT as an electronic product

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