Action of base on non-enolisable carbonyl compounds. Part II. Cleavage of some anthraquinones

Abstract

Anthraquinone, several methoxyanthraquinones, and 1- and 2-chloroanthraquinone are cleaved in high yield to afford mixtures of benzoic and/or phthalic acids when treated for up to 4 h with an excess of the butoxide–water reagent in 1,2-dimethoxyethane at ca. 85°. In favourable cases cleavage can be conveniently effected at 20°. To determine how substituents affect the pattern of cleavage the mixtures of acids produced were esterified and the mixtures of esters analysed by g.l.c. Phenanthrene-9,10-quinone undergoes a benzilic acid rearrangement when treated with the butoxide–water reagent and in the presence of oxygen a high yield of biphenyl-2-carboxylic acid is obtained.