Phenylmethylene as intermediate in acid-catalyzed oxidation of styrene epoxide

Resumo

The absorption spectrum of iminium ylide (λ_max = 450 nm) has been registered under the conditions of acid-catalyzed consumption of styrene epoxide under the influence of p-toluenesulfonic acid (MeCN, Bu^tOH (90 vol.%) + chlorobenzene (10 vol.%), 343 K) in the presence of pyridine. The spectrum coincides with the spectrum of the ylide product of the interaction of pyridine with phenylcarbene of phenylmethylene formed in the conventional flash-photolytic preparation of carbene from diazo derivative. The result confirms the earlier assumption on the formation of the particles of carbene nature reacting with oxygen in the epoxy-acid system. In the absence of O₂ these particles destruct introduced hydroperoxides. The spectra of corresponding carbonyl oxide (λ_max ≈ 408, 400 nm) in the presence and absence of pyridine were recorded in acetonitrile.