Mass spectra of 5‐styryl and 5‐acylpyrazoles

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High‐resolution, electron‐impact, mass‐spectrometric measurements have been made on three types of pyrazoles. Type 1 comprised ethyl 5‐styrylpyrazole‐3‐carboxylates having in the α‐position of the styryl group either a hydrogen atom, a methyl, or a phenyl group. Type II were 1,3,5‐trisubstituted pyrazoles having phenyl (or p‐substituted phenyl) groups in position 1, amide or carboxylate groups in position 3, and styryl (or α‐substituted styryl) groups in position 5. Type III differed from type II in possessing a readily cleaved acyl or aroyl group instead of the styryl group. The compounds containing styryl groups gave significant ions corresponding to the formation of polycyclic heteroaromatic rings, in addition to various other fragments derived from such rings. Intensities and accurate mass‐measurements are given for all ions having intensities exceeding 5% of the base peak. Copyright © 1974 Journal of Heterocyclic Chemistry

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Journal of Heterocyclic Chemistry