Trapping and identification of free radicals in the oxidation of some substituted hydrazines

Abstract

Free radicals produced during treatment of substituted aroylhydrazines with sodium hydride in the presence of air have been scavenged with 2-methyl-2-nitrosopropane. The resulting stable nitroxides were examined by e.s.r. spectroscopy. A number of heterocyclic nitroxides were generated in this manner and by oxidation of heterocyclic amines with pentyl nitrite and also by oxidation of hydrazines by metallic oxides. Product analysis of some of these reactions carried out in the absence of nitrosobutane has shown a good correspondence between the structure of the trapped radical and the probable major reaction intermediates. The results provide further evidence for the versatility of the radical-scavenging (spin-trapping) technique. Phenylation by oxidation of phenyldrazine with silver oxide in suitable solvents has been shown to be critically dependent on the concentration of phenylhydrazine in the reaction medium.