2-Chloro-1,3-thiazole-4-carboxylic acid

41731-52-6

5198-87-8

The general procedure for the synthesis of 2-chloro-1,3-thiazole-4-carboxylic acid from ethyl 2-chlorothiazole-4-carboxylate was as follows: 14.0 g (73.1 mmol) of ethyl 2-chlorothiazole-4-carboxylate was slowly added to 11.0 g (0.17 mol, 85% purity) of potassium hydroxide in a solution of ethanol/water (1:3, 200 mL), keeping the reaction temperature at 0 °C. The reaction mixture was stirred at room temperature for 16 hours before being diluted with water and washed twice with ether. Subsequently, the aqueous layer was acidified to pH=5.5 with concentrated hydrochloric acid and stirring was continued at room temperature for three days. The precipitate formed was collected by filtration and dried under vacuum at 40°C to give 7.0 g (56% yield, 95% purity) of 2-chloro-1,3-thiazole-4-carboxylic acid as a brown solid product.