AN EXPLANATION OF SOME ANOMALOUS ELECTRON SPIN RESONANCE SPECTRA DERIVED FROM ALKOXY- AND BROMO-BENZOQUINONES

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.