Preparation method of highly selective 3-methyl-2-nitrobenzoic acid

Abstract

The invention discloses a preparation method of 3-methyl-2-nitrobenzoic acid. 3-methylbenzoic acid alkyl ester is used as raw material in nitrification, two-grade selectivity and high yield are realized, and the amount of waste acid was reduced. In nitrification product, only 3-methyl 2-nitrobenzoic acid alkyl ester and 3-methyl-4-nitrobenzoic acid alkyl ester are hydrolyzed after separation to obtain 3-methyl 2-Nitrobenzoic acid and 3-methyl-4-nitrobenzoic acid. The process is simple, and suitable for industrial production.

Description

technical field

[0001] The invention belongs to the field of organic synthesis, and specifically relates to a preparation method of 3-methyl-2-nitrobenzoic acid. Background technique

[0002] 3-Methyl-2-nitrobenzoic acid is the raw material for the synthesis of 2-amino-5-chloro-N,3-dimethylbenzamide, and is widely used in the pesticide and pharmaceutical markets.

[0003] At present, known about the preparation method of 3-methyl-2-nitrobenzoic acid mainly contains following several kinds:

[0004] In the literature Qin Tao's master's thesis of Nanjing University of Science and Technology "Study on the Nitration Selectivity of Meta-Substituted Toluene", 3-methyl-2- Methyl nitrobenzoate produces a large amount of waste acid during the reaction, which is difficult to handle.

[0005] Literature Tetrahedron Letters, 47 (49): 8651–8652; 2006; 3-methylbenzoic acid was used as raw material, urea mononitrate or nitrourea was used as nitrating reagent to synthesize crude 3-methyl-...