Method for synthesizing 2-methoxy-4-amino-5-ethylsulfonyl benzoic acid in two steps

Abstract

The invention discloses a method for synthesizing 2-methoxy-4-amino-5-ethylsulfonyl benzoic acid in two steps. The method comprises the following steps of: (a) reacting 2-methoxy-4-acetaminomethyl benzoate with chlorosulfonic acid for 6-9 hours in a reactor and then carrying out hydrolysis separation to obtain 2-methoxy-4-acetamino-5-sulfonylchloromethyl benzoate; and (b) reacting the obtained 2-methoxy-4-acetamino-5-sulfonylchloromethyl benzoate with sodium sulfite and diethyl sulfate for 6-9 hours under the reflux condition and finally carrying out the operations such as aciding out with hydrochloric acid to obtain the target product 2-methoxy-4-amino-5-ethylsulfonyl benzoic acid, wherein the mole ratio of 2-methoxy-4-acetaminomethyl benzoate to chlorosulfonic acid is 1:(5-8); and the mole ratio of 2-methoxy-4-acetamino-5-sulfonylchloromethyl benzoate to sodium sulfite to diethyl sulfate is 1:(4-6):(2-3). The method has the advantages that the process route is simple; the product yield is high; the total yield can reach 75%; the purity reaches 99.5%; the product has good quality and white appearance; the defects of long synthetic route, low yield, poor product quality and the like in the original processes are overcome so that the method is more suitable for industrial production requirements; and a new method is provided for synthesizing 2-methoxy-4-amino-5-ethylsulfonyl benzoic acid.