Patent ID: 8461355

Claim:
A method of preparing 3,4-ethylenedioxythiophene, comprising: (1) mixing 2,2′-thiodiacetic acid and ethanol and then adding sulfuric acid as a catalyst in a microwave reactor heated by a 2.45 GHz microwave at a power of 500-1000 W to perform an esterification reaction for 15-30 minutes to obtain diethyl thioglycolate, wherein an equivalent ratio of the sulfuric acid and the 2,2′-thiodiacetic acid is no more than 1; (2) mixing the diethyl thioglycolate and diethyl oxalate and then adding to a first solution containing a first electron donor in the microwave reactor heated by the 2.45 GHz microwave at a power of 100-500 W to perform a condensation reaction for 20-60 minutes to obtain 2,5-diethoxycarbonyl-3,4-dihydroxythiophene; (3) mixing the 2,5-diethoxycarbonyl-3,4-dihydroxythiophene and 1,2-dihaloethane and then adding to a second solution containing a second electron donor in the microwave reactor heated by the 2.45 GHz microwave at a power of 500-1000 W to perform an etherification reaction for no more than 30 minutes to obtain 2,5-diethoxycarbonyl-3,4-ethylenedioxythiophene; (4) mixing the 2,5-diethoxycarbonyl-3,4-ethylenedioxythiophene and NaOH in the microwave reactor heated by the 2.45 GHz microwave at a power of 500-1200 W to perform a hydrolysis reaction for no more than 20 minutes to obtain 2,5-dicarboxy-3,4-ethylenedioxythiophene; and (5) mixing the 2,5-dicarboxy-3,4-ethylenedioxythiophene and Cu 2 Cr 2 O 5 in the microwave reactor heated by the 2.45 GHz microwave at a power of 500-1200 W to perform a decarboxylation reaction for no more than 30 minutes to obtain 3,4-ethylenedioxythiophene.