Electron impact studies on oximes: Mass spectra of the condensation products of aniline,phenol and thiophenol with benzhydroximoyl chloride

The condensation products derived from aniline, phenol and thiophenol by treatment with benzhydroximoyl chloride, exhibited a stepwise (in the first two cases) or concerted (in the third case) loss of OH. and C6H5N from the corresponding skeletally rearranged molecular ions, affording C6H5C?X]⁺ ions (where X = NH or o or S) when subjected to electron impact. The process has been substantiated by deuterium labelling and exact mass measurements. The base peaks in all the spectra were due to the aniline, phenol and thiphenol radical ions as the case may be, obtained by a shift prior to fragmentation of the oxime hydrogen to the heteroatom contained in these ions.