On the Mechanism of the Reaction of Nitrosobenzenes with Benzenethiol: the Intermediacy of Aminoxyls and Their Deoxygenation

The reaction of benzenethiol with several substituted nitrosobenzenes carried out inside the cavity of an EPR spectrometer evidences the formation of adducts through the detection of the corresponding thionitroxides. The macroscale reaction of benzenethiol with nitrosobenzene confirmed the formation of the adduct and clarified the nature of the intermediates. The formation of azoxybenzene, aniline and nitrobenzene shows that an electron-transfer process between nitrosobenzene and benzenethiol is in competition with nucleophilic addition of the latter to the former compound. The identification of S-phenylbenzenethiosulphinate as well as the isolation of compound 9, bearing a sulphinyl group on a benzene ring, implies the formation of a sulphinyl radical, which is considered to be responsible for the formation of the sulphinylamide. The formation of the sulphenamide, the main reaction product, is attributed to the interaction of thiyl radicals with the intermediate thionitroxides. The crystal structure of S-methyl-S-phenyl-N-(o-sulphonylphenyl)benzenesulphilimine the unexpected product of the methylation of compound 9, is also described.