Secondary Free Radial Intermediates in the Synthesis of 2-Methyl-6-Nitroindazole

摘要

Four distinct free radical intermediates were detected by electron spin resonance (e.s.r) spectroscopy during the spontaneous conversion of an isomeric mixture of 2,4 and 3,4-dinitro-N,N-dimethylbenzylamine to 2-methyl-6-nitroindazole. These spectra include an iminoxyl radical, R-N=N-O. (not reproducible); a dimethylnitroxyl radical, (CH3)2NO. (reproducible); and two structurally unidentified radicals (also reproducible). Free radial intermediates were detected only when the reaction was started by nitrating 4-nitro-N,N-dimethylbenzylamine. No free radicals were detected when the reaction was started by mixing separately prepared 2,4 and 3,4-dinitro-N,N-dimethyl-benzylamine. (3,4-dinitro-N,N-dimethylbenzylamine alone does not convert to 2-methyl-6-nitroindazole).