The ring-opening reactions of cyclobutylmethyl and cyclobutenylmethyl radicals

Abstract

Rate constants for the ring-opening reactions of cyclobutylmethyl, 1-cyclobutyl-1-methylethyl, and cyclobut-2-enylmethyl radicals have been determined over a range of temperatures by kinetic e.p.r. spectroscopy. The results can be represented by equations (i)–(iii), respectively. The results are compared with those for ring, log (k₃/s^–1)=(13.1 ± 1.4)-(49.8 ± 7.5 kJ mol^–1)/2.3RT(i) log (k₅/s^–1)=(13.6 ± 1.6)-(58.1 ± 9.0 kJ mol^–1)/2.3RT(ii) log (k₁₀/s^–1)=(12.2 ± 1.4)-(42.2 ± 8.0 kJ mol^–1)/2.3RT(iii) opening of other cycloalkylmethyl radicals. The rate constants for self-reaction of n-pentyl radicals in toluene solution have also been measured over a temperature range and found to fit relation (iv). log (2k_t/dm³ mol^–1 s^–1)=(12.3 ± 0.7)-(10.5 ± 3.0 kJ mol^–1)/2.3RT(iv)