Electron spin resonance studies of aliphatic nitroxides. Part III. A conformational study of radicals from 4-alkylpiperidines and piperazine

Abstract

The e.s.r. spectra of the nitroxide radicals produced by oxidation of 4-methyl-, 4-n-propyl-, and 4-t-butyl-piperidine, piperazine, and 4-N-methylpiperazine have been measured in aqueous solution. The spectra have been analysed in terms of a fast exchange between two unequally populated chair forms and estimates have been made of the free-energy differences between conformational isomers.