2,5-Thiophenedicarboxylic acid, 3,4-dihydroxy- synthesis

Yield:14282-58-7 0.7 g

Reaction Conditions:

with sodium acetate;sodium hydroxide in water at 100 - 120; for 4.5 h;Inert atmosphere;

Steps:

1.c Synthesis of 3,4-dihydroxy-2,5-dicarboxylic acid thiophene

In a 1-liter four-necked flask, 24.4 g (0.18 mol) of sodium acetate · trihydrate (reagent special grade, manufactured by Kishida Chemical Co., Ltd) and 3 . 1 g (74.8 mmol) of sodium hydroxide (special grade reagent, manufactured by Kishida Chemical Co., Ltd.) were charged, and the mixture was heated to 120 ° C. Thereto, 1.3 g (5.0 mmol) of 3,4-dihydroxy-2,5- dicarboxylic acid thiophene diethyl ester obtained in b) and 5.0 g of water were added and stirred at 120 ° C for 1.5 hours, further, the reaction was continued at 100 ° C for 3 hours. After completion of the reaction, 62.3 g of water and 33.2 g (0.32 mol) of 35% hydrochloric acid were added to the reaction solution at 25 to 30 ° C, and the reaction solution was extracted with ethyl acetate and washed with water and anhydrous magnesium sulfate (Specialgrade reagent,manufactured by Kanto Chemicalinc) was added & dehydrated and then concentrated at 55 ° C/16 to 20 mmHg to obtain 0.7 g of a brown solid.

References:

JP5998836,2016,B2 Location in patent:Paragraph 0059; 0064