Friedel–Crafts acylations of aromatic hydrocarbons. Part VII. The acetylation and benzoylation of 2,3-dimethylnaphthalene

Abstract

The Friedel–Crafts acetylation or benzoylation of 2,3-dimethylnaphthalene affords mixtures of 1-, 5-, and 6-monoacyl, and 1,5- and 1,6-diacyl derivatives. The proportions of these products depend on the reaction conditions. The main monobenzoylation product is 1-benzoyl-2,3-dimethylnaphthalene, but acetylation favours the formation of 1-acetyl-6,7-dimethylnaphthalene. This anomaly is explained in terms of the steric requirements of the acylation species. Competitive Perrier acetylation of 2,3-dimethylnaphthalene and naphthalene in chloroform solution gives the following relative reactivities of the nuclear positions: 1-naphthyl 1·00, 2-naphthyl 0·31, 2,3-dimethyl-1-naphthyl 1·59, 2,3-dimethyl-5-naphthyl 7·14, and 2,3-dimethyl-6-naphthyl 3·68. The corresponding values for benzoylation are 1·00, 0·04, 172, 38·2, and 7·7, respectively.