Mass spectral fragmentation of thioesters. 1—Identification of low energy, slow processes

A variety of thiol and thion esters, including acetates and benzoates with n-butyl and β-phenethyl alkyl groups, have been studied by electron impact mass spectrometry. Several rearrangement ions were documented and their persistence in low voltage and field ion spectra demonstrated. Among the significant ions found in the rich thion spectra, the most general requires O to S rearrangement of the alkyl group and subsequent cleavage to yield acyl ions (CH3CO or PhCO). This process is more important in longer chain compounds than in the methyl and ethyl homologues studied previously.