The influence of crown ethers on cation migration processes. Part 6.—The 1,4-naphthoquinone radical anion

Abstract

The radical anion of 1,4-naphthoquinone has been prepared by alkali-metal reduction, employing Li, Na, K and Cs, in 1,2-dimethoxyethane in the presence of 18-crown-6, 15-crown-5 and 12-crown-4. Linewidth alternation is observed in the e.s.r. spectra of some of these systems owing to intramolecular cation migration between equivalent sites adjacent to the two carbonyl groups. In some systems a species is observed with a much narrower spectrum than that observed in the absence of a crown ether. Remarkably, it is apparent that the crown ethers do not appear to show great specificity towards the counterions which match the size of their cavities.