Rate constants of the recombination of alkyl radicals with nitroxide b
iradicals in dioxane and ethyl benzene exceed rate constants with 'par
ent' mono radicals by 10%-50%. The difference in reactivity is attribu
ted to spin catalysis of the recombination reaction which occurs in th
e encounter pair of an alkyl radical with one of the biradical termini
by the second spin-carrying terminus.