Mass spectra of some 2‐(4′‐butyl‐3,′5′‐dimethylpyrazol‐1′‐yl)‐6‐substituted benzothiazoles

The fragmentation of the title compounds on electron impact has been studied and the major processes interpreted. The base peak invariably appears at [M  43] + whose origin from the butyl chain has been traced with the help of metastable ion studies and accurate mass measurements. Loss of methyl cyanide, involving the decomposition of the pyrazole moiety, is observed only from the fragment ions.