Electron spin resonance spectroscopy as an analytical tool

Abstract

Monomethoxy- and dimethoxy-p-benzoquinones have been investigated in alkaline aqueous methanol and ethanol by electron spin resonance spectroscopy. All compounds show solvent exchange of the methoxy group(s). 2,6-Dimethoxy-p-benzoquinone dissolved in aqueous ethanol exhibits spectra of three radicals, due to partial exchange of none, one and two methoxy groups. Computer simulations demonstrate that γ-protons of the ethoxy group(s) give rise to splittings comparable to the linewidths. Monomethoxy-p-benzoquinone undergoes alkoxylation solely leading to the 2,5 analogue.