A kind of method taking thiophene-2-formic acid as raw material synthesis 5-chlorothiophene-2-formic acid
A technology of chlorothiophene and formic acid, applied in the field of synthesizing 5-chlorothiophene-2-carboxylic acid, can solve the problems of high reagent price, high corrosion of LDA, unfavorable amplification, etc., achieve simple operation and post-treatment, facilitate industrial production, and solve The effect of dealing with the problem
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Embodiment 1
[0032] Add 392g of concentrated sulfuric acid to the reactor with stirring and thermometer, cool down to 0°C, add 128g of thiophene-2-carboxylic acid, at -5~5°C, add 80g of trichloroisocyanuric acid in batches, add 4h, TLC point The plate method is used to monitor the reaction to reach the end point, and the reaction solution obtained after the reaction is crystallized in ice water equivalent to twice the volume of the reaction solution, filtered, washed with water to obtain 200 g of the crude product, and the crude product is dissolved in dichloromethane equivalent to twice the mass of the crude product , washed twice with water, each time with 50 g of water, then concentrated the organic phase, and then recrystallized with ethanol equivalent to 3 times the volume of the concentrated organic phase to obtain 133.7 g of pure product, with a purity of 98.3% and a yield of 82.2%.
Embodiment 2
[0034] Add 484g of acetic acid and 18g of water into the reactor with stirring and thermometer, lower the temperature to 10°C, add 128g of thiophene-2-carboxylic acid, control the temperature at 10-30°C, add 134g of trichloroisocyanuric acid in batches, and complete the addition within 4 hours , TLC point plate method to monitor the reaction to reach the end point, add the reaction solution obtained after the reaction to crystallize in ice water equivalent to 2 times the volume of the reaction solution, filter, wash with water to obtain 194g of crude product, and dissolve the crude product in ice water equivalent to 2 times the mass of the crude product In dichloromethane, wash with water twice, each time with 50g of water, then concentrate the organic phase, and recrystallize with ethanol equivalent to 3 times the volume of the concentrated organic phase to obtain 118.5g of pure product, with a purity of 97.6%, and a yield of 72.9 %.
Embodiment 3
[0036] Add 392g of acetic acid and 509g of dichloromethane into the reactor with stirring and thermometer, cool down to 10°C, add 128g of thiophene-2-carboxylic acid, control the temperature at 10-20°C, add 118g of trichloroisocyanuric acid in batches, 4h After adding, let it stand, separate the liquids, wash the water layer twice with 50ml of dichloromethane, combine the organic phases to concentrate, and recrystallize with ethanol equivalent to 3 times the volume of the concentrated organic phase to obtain 113.8g of pure product with a purity of 98.6%. , yield 70.0%.
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