Kinetic applications of electron paramagnetic resonance spectroscopy. 34. Rate constants for spin trapping. 2. Secondary alkyl radicals

The cyclization of the secondary 6-hepten-2-yl radical to form the primary 2-methylcyclopentylcarbinyl radical has been studied by kinetic EPR spectroscopy. The rate constant for this cyclization, kc, can be represented by log (kc/s-1) = (9.8 \ub1 0.3) -(6.4 \ub1 0.3)/\u3b8 where \u3b8 = 2.303RT kcal/mol. This cyclization has been used as a standard to measure the absolute rate constants for the spin trapping of secondary alkyls in benzene at 40\ub0C by a few of the more commonly employed spin traps. These results are compared with the previously determined4 kT values for trapping primary alkyl radicals under the same conditions. Relative kT values for trapping of the tertiary 2-phenylprop-2-yl radical have also been measured. \ua9 1979 American Chemical Society.Peer reviewed: YesNRC publication: Ye