Mass spectra of thioamides derived from resorcinol and its methyl ethers

The electron ionization-induced fragmentation patterns of thioamides, deriv ed from resorcinol and its methyl ethers, are studied. Fragmentation pathwa ys depend both on the N-substituent group and the benzene ring substituents (OH or OCH3 groups). Primary fragmentations, common for all compounds stud ied, are the eliminations of H-., SH., NHR. and CNHR. radicals. The mechani sm of the SH. elimination is different for the 2-OH and 2-OCH3 derivatives. Rationalization for this observation, proved by deuterium labelling, is gi ven.