The ring-opening reactions of cyclobutylmethyl and cyclobutenylmethyl radicals

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).