Anthraquinone dyes. Part IV. Nitration of 2-(3-chloro-4-methyl-benzoyl)benzoic acid

Abstract

The principal product of the nitration of 2-(3-chloro-4-methylbenzoyl)benzoic acid is 2-(3-chloro-4-methyl-6-nitrobenzoyl)benzoic acid, formed in 70–80% yield. In addition, 10–15% of 2-(3-chloro-4-methyl-2-nitrobenzoyl)- and 2-(3-chloro-4-methyl-5-nitrobenzoyl)-benzoic acid are formed. This result is in disagreement with a semiquantitative estimate, based on sigma constants, from which 2-(3-chloro-4-methyl-5-nitrobenzoyl)-benzoic acid would be the principal reaction product expected. In a study of the nitration of 2-(3-chloro-4-methyl-benzoyl)benzoic acid, authentic specimens of 1,4-dichloro-2-methyl-, 1,2-dichloro-3-methyl-, and 2,3-dichloro-1-methyl-derivatives of anthraquinone were prepared.