The formation of nitriles from the reaction between benzaldoxime (benzaldehyde oxime) and thiocarbonyl compounds by free radical mechanisms
Abstract
The reaction of benzaldoxime with thiobenzoyl and NN-dimethylthiocarbamoyl chlorides gives nitrile in 55–60% yield from both E- and Z-isomers. The thiobenzoyl group fragments to a mixture of biphenyl, dibenzoyl disulphide, and carbonyl sulphide, indicating a radical process. This is confirmed by studies of the decomposition of the adducts of benzaldoxime and aromatic isothiocyanates to nitrile, disubstituted urea, and carbonyl sulphide. Strong polarisations of the carbon nuclei of nitrile detected in the 13C n.m.r. spectra show that elimination proceeds in a radical cage. Polarisations in the hydrogen nuclei of side products are explained by a simultaneous rearrangement of the initial adduct through a radical pair, and escape of the iminyl radical to give imine by hydrogen atom abstraction.