Kinetic applications of electron paramagnetic resonance spectroscopy. 31. Rate constants for spin trapping. 1. Primary alkyl radicals

Rate constants for the addition of primary alkyl radicals to most of the commonly employed spin traps have been determined at 40°C using the [1-13C]-5-hexenyl radical as the primary standard. In the presence of a spin trap there is a competition between direct addition of this radical to give a 13C labeled spin adduct and its cyclization to the cyclopentylmethyl radical which, when it adds to the trap, gives an unlabeled spin adduct. The results obtained with this radical have been extended by means of competitive experiments using pairs of spin traps and the 1-hexyl radical. Additional rate data has been obtained by measurement of spin adduct concentrations under steady-state conditions.