Synthetic method of 5-chloro-2-thiophenecarboxylic acid

The invention discloses a synthetic method of 5-chloro-2-thiophenecarboxylic acid. 2-bromo-5-chlorothiophene reacts with magnesium to generate a Grignard reagent of 5-chloro-2-thienylmagnesium bromide, and then the 5-chloro-2-thienylmagnesium bromide reacts with dry ice and is hydrolyzed under the acid condition to generate the 5-chloro-2-thiophenecarboxylic acid. The synthetic method is simple, and the yield and purity of the product are high. The reaction equation is shown in the figure.