The Friedel-Crafts acylation of aromatic halogen derivatives. Part IV. The benzoylation of o-, m- and p-dichlorobenzenes

Abstract

The Friedel-Crafts benzoylation of the isomeric dichlorobenzenes has been studied in nitrobenzene solutuon. The ortho-isomer gives mainly 3,4-dichlorobenzophenone, with small yields of 2,3-dichlorobenzophenone, o- and p-chlorobenzophenone, and benzophenone. The meta-isomer gives mainly 2,4-dichlorobenzophenone together with a little of the 2,6-isomer. The para-isomer gives the normal 2,5-dichlorobenzophenone, and products of rearrangement (3,4-dichlorobenzophenone), and dechlorobenzoylation. Competitive acylations show that the ortho-isomer is more reactive, meta-isomer as reactive, and para-isomer less reactive, than calculated from the partial-rate factors of benzoylation of chlorobenzene.