Conformational interconversion in the 1,1,4,4-tetramethyltetralin-2-ketyl radical anion by electron spin resonance

Abstract

A moderately stable ketyl free radical containing two protons bonded to the carbon atom in the α-position of the carbonyl group has been prepared by alkali metal reduction of 1,1,4,4-tetramethyl-2-tetralone. The e.s.r. spectrum shows a line broadening effect which is explained on the basis of the conformational interconversion of the radical anion between two equivalent conformations. The thermodynamic parameters of the process are obtained and their dependence on the counter ion is discussed.