Sterically hindered aromatic compounds. XI. Spectral and product studies of the decomposition of N-nitrosoacetanilides

Article abstract of DOI:10.1139/v82-090

Decomposition of N-nitroso-2,4,6-tri-tert-butylacetanilide (1) in benzene forms products 2,4,6-tri-tert-butylphenyl acetate (3), 3-(3,5-di-tert-butylphenyl)-2-acetoxy-2-methylpropane (4), and hydrocarbons 3-(3,5-di-tert-butylphenyl)-and 1-(3,5-di-tert-butylphenyl)-2-methylpropene (5 and 6) explained by a reactive aryl cation (2), the rearranged products (4, 5, 6) originating from a 1,5-hydride shift from an ortho tert-butyl group in 2.In contrast, decomposition of 1 in triethylamine forms products 1,3,5-tri-tert-butylbenzene (10), 2,4,6-tri-tert-butylacetanilide (15), and 2-(3,5-di-tert-butylphenyl)-2-methylpropanal oxime (13), expected of a free radical pathway.Electron spin resonance evidence is given for intermediates formed by rearrangement of the 2,4,6-tri-tert-butylphenyl radical and spin trapped by the nitroso group of 1.CIDNP and esr studies on the dediazoniation of N-nitrosoacetanilide and aniline in the presence of tertiary amines support the proposed electron transfer mechanism.The results are briefly discussed in terms of the role of steric effects and electron transfer in the dediazoniation of nitrosoacetanilides and diazonium salts.