Preparation method of 3,4-ethylenedioxythiophene
A method of preparing 3,4-ethylenedioxythiophene is provided. The preparation is performed by microwave heating to greatly increase the yield and decrease the reaction time, energy consumption, solvent usage, and environmental damage.
1. 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.
2. The method of claim 1 , wherein an equivalent ratio of the 2,2′-thiodiacetic acid and the ethanol in the step (1) is 1/12-1/6.
3. 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;
(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, wherein an equivalent ratio of the diethyl thioglycolate and diethyl oxalate is 1/2-1;
(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.
4. The method of claim 3 , wherein an equivalent ratio of the first electron donor and the diethyl thioglycolate in the step (2) is not less than 2.
5. The method of claim 3 , wherein an equivalent ratio of the first electron donor and the diethyl thioglycolate in the step (2) is 2-4.
6. 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;
(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, wherein an equivalent ratio of the 2,5-diethoxycarbonyl-3,4-dihydroxythiophene and 1,2-dihaloethane is 1/3 -1;
(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.
7. The method of claim 6 , wherein an equivalent ratio of the second electron donor and 2,5-diethoxycarbonyl-3,4-dihydroxythiophene in the step (3) is not less than 2.
8. The method of claim 6 , wherein an equivalent ratio of the second electron donor and 2,5-diethoxycarbonyl-3,4-dihydroxythiophene in the step (3) is 2-4.
9. 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;
(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, wherein an equivalent ratio of the 2,5-diethoxycarbonyl-3,4-ethylenedioxythiophene and NaOH is 1/5-1/3; 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.
10. 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;
(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, wherein an equivalent ratio of Cu 2 Cr 2 O 5 and the 2,5-dicarboxy-3,4-ethylenedioxythiophene is 0.2-0.7.