A re-examination of the Friedel–Crafts acetylation of 2-bromonaphthalene

Abstract

Acetylation of 2-bromonaphthalene (I) gives mixtures of 1-acetyl-7-bromonaphthalene (II) and 2-acetyl-6-bromonaphthalene (III), in the ratio (II)/(III) of 0·53 in nitrobenzene, 2·2 in carbon disulphide, and 3·3 in chloroform. Competitive Perrier acetylation shows that the rate of attack on compound (I) is one seventh that on naphthalene. The 8-position of compound (I) is 0·58 times as reactive, and the 6-position 0·63 times as reactive, as the α- and β-positions, respectively, of naphthalene. It is shown that rearrangement is not responsible for the formation of β-isomers in the acetylation of compound (I) or of naphthalene.