An explanation of some anomalous electron spin resonance spectra derived from alkoxy- and bromo-benzoquinones

Abstract

Alkaline solutions of alkoxybenzoquinones in various alcohols undergo rapid exchange, the alkoxy-groups being replaced by the solvent alcohol. Reduction of the resulting quinones gives e.s.r. spectra compatible with this alkoxy exchange.

2- and 3-Bromo-5-t-butyl-1,4-benzoquinones give preponderantly isomeric methoxyquinones when briefly treated with methanolic alkali. An addition–elimination mechanism is suggested for this rearrangement, and various dihydroquinonoid products have been isolated in support of this mechanism.

The reaction of 2,3-dibromo-5-t-butyl-1,4-benzoquinone with methanolic alkali leads chiefly to 3-methoxy-5-t-butyl-1,4-benzoquinone and related compounds. The position of substitution is strongly influenced by solvation of the intermediate anion, and can be reversed in dimethyl sulphoxide.