NUCLEAR MAGNETIC RESONANCE SPECTRA OF METHYL SUBSTITUTED AZOXY COMPOUNDS

Abstract

“NMR spectra are used to establish the configuration of the \emph{cis} azoxy group, and to show the existence of two isomers in the mono-substituted compounds of this class. All the known mono-substituted and di-substituted p-methyl azo and azoxy compounds were prepared and the chemical shifts of the methyl peaks, relative to tetramethylsilane, were obtained. In the compound \emph{cis} p.p’-dimethylazoxybenzene two methyl peaks were seen (at 112.7 and 105.2 cps), clearly indicating the nonequivalence of the substituents and climinating the possibility of a symmetrical structure as: [FIGURE] and strongly indicating the structure: [FIGURE] for the \emph{cis} azoxy group, analogous to the known configuration of the corresponding \emph{trans} isomers. This contention is further strengthened by the spectral evidence for two isometic \emph{cis} azoxybenzenes from the oxidation of \emph{cis} p-methylazobenzene. Two methyl peaks of approximately the same intensity were seen (at 112.6 and 105.4 cps). Only the compound whose methyl resonance occurred at 112.6 cps was isolated, and on decompositions formed ($\alpha$) \emph{trans} p-methylazoxybenzene.[FIGURE] We believe this to be the first example reported of a mono-substituted \emph{cis} axozy compound.”