Mass spectrometric study of the isomerism of aromatic aldoximes

Abstract

When small samples of 2- and some 3-substituted benzaldoximes are evaporated into the ion source of a mass spectrometer, the records of molecular-ion current with time show two maxima. These maxima have been shown to be due to the syn and anti isomers of the benzaldoximes, which have different heats of sublimation. These differences may represent the heats of polymerisation of the monomers, assuming that the non-planar anti isomers exist in the monomeric form. A mass spectrometric method of identifying the isomers and estimating their heats of sublimation has been developed.