High-resolution mass spectrometry. Part IV. Behaviour of isothiazoles under electron impact

The mass spectral behaviour of a number of isothiazoles has been studied. It appears feasible to determine the position of substitution of these compounds from their mass spectra. Some of the ions in the spectra of the three monomethylisothiazoles are considered to arise from ring-expanded molecular ions. The anomalous elimination of carbon monoxide occurs from isothiazole-4-carboxamide.