Nitroxide radicals. Part VI. Stability of meta- and para-alkyl substituted phenyl-t-butylnitroxides

Abstract

Aryl-t-butylnitroxides with primary or secondary para-alkyl substituents disproportionate during isolation to the parent hydroxylamines and the corresponding quinone methide imine N-oxides. These usually react further to yield dimeric, trimeric, or polymeric hydroxylamines, some of which fragment to give amines and p-acylphenyl-t-butylhydroxylamines. Aryl-t-butylnitroxides with meta-alkyl substituents, which hinder attack at the para-position, or with tertiary alkyl para-substituents are sufficiently stable to be isolated.