Patent ID: 6369239
Filing Date: 2002-04-09
Classification: C07D,Y02P

Abstract:
A process for the preparation of 3,4-dialkoxythiophenes of the formula (I) or 3,4-alkylenedioxythiophenes of the formula (II) comprising(1) decarboxylating, respectively, a parent 3,4-dialkoxy-2,5-thiophenedicarboxylic acid of the general formula (III) â€ƒwherein R1 and R2 are straight-chain or branched alkyl having 1 to 15 carbon atoms, or a parent 3,4-alkylenedioxy-2,5-thiophenedicarboxylic acid of the general formula (IV) â€ƒwherein X is optionally substituted â€”(CH2)nâ€” and n is an integer from 1 to 12, in a solvent or diluent that has a higher boiling point than the decarboxylated product and is not an aromatic amine, and (2) separating the end product from the higher-boiling solvent or diluent by distillation.