A kinetic electron spin resonance study of ring fission in methyl-substituted cyclobutylmethyl radicals

Abstract

Rate constants for the ring-opening reactions of cis- and trans-2-methylcyclobutylmethyl, cis- and trans-3-methylcyclobutylmethyl, and 2,2-dimethylcyclobutylmethyl radicals have been determined over a range of temperatures by kinetic e.s.r. spectroscopy. For the limited series of cyclobutylmethyl radicals the activation energies for ring-opening show a linear correlation with the enthalpies of the rearrangements. Barriers to internal rotation of the trans methyl groups have been determined from exchange broadening in the e.s.r. spectra of trans-2-methylcyclobutylmethyl and 2,2-dimethylcyclobutylmethyl radicals.