A convenient method for the preparation of 4 - n - alkyl - 4'' -cyano - p - terphenyl

Abstract

A new and general procedure for the preparation of 4-n-alkyl-4'' -cyano-p-terphenyl is described starting from p-terphenyl. This procedure consists of the Friedel-Crafts reaction on p-terphenyl with an acyl halide and reducing the resulting ketone by the Wolff-Kishner method to the 4-n-alkyl-p-terphenyl. This is acylated with acetyl chloride to the corresponding 4-n-alkyl-4''- acetyl-p-terphenyl, which in turn is oxidised to the carboxylic acid. This acid is converted to the amide through its acid chloride. Dehydration of this amide affords the desired 4-n-alkyl-4''- cyano-p-terphenyl. This convenient method offers better yields than the procedure of Gray et al.1 and could also be utilised for the preparation of 4-n-alkoxy-, and 4-n-alkyl-4' -cyano biphenyls. In addition to the cyano derivatives, some intermediate compounds also exhibit mesomorphic properties.