Electron bombardment induced fragmentation of substituted oxathiolanes

The mass spectral fragmentation patterns of 1,3-oxathiolane and 2-, 4-, and 5-substituted oxathiolanes have been recorded. The various fragments have been identified by high-resolution mass spectrometry when appropriate. Of the five possible modes of ring cleavage to produce two- and three-atom fragments only two modes are actually observed. The mode of fragmentation of the 1,3-oxathiolane ring differs from that proposed for 1,3-dioxalane and in all probability occurs in multistep processes.