An Improved Procedure for the Synthesis of 3,4-ethylenedioxythiophene

Abstract

An improved procedure for the synthesis of 3,4-ethylenedioxythiophene is reported starting from ethyl chloroacetate. Reaction with sodium sulfide gave diethyl thiodiglycolate which was then reacted with diethyl oxalate, and then 1,2-dibromoethane to give 2,5-dicarbethoxy-3,4-ethylenedioxythiophene. Hydrolysis, and decarboxylation gave 3,4-ethylenedioxythiophene in 16% overall yield. The structures of the key intermediates in synthetic routes were confirmed, and every step was optimised, to give a procedure suitable for large-scale industrial production.