A Study of Selected Ions in the Mass Spectra of Benzenethiol and Deuterated Benzenethiol

Partial mass spectra are presented for benzenethiol, C/sub 6/H/sub 5/SH, and deuterated benzenethiol, C/sub 6/H/sub 5/SD. The changes in ion intensities that result from deuterium labeling were studied to determine the structure of the parent ion before fragmentation. A seven-membered ring structure for the parent ion is proposed as precursor for some of the ions studied, whereas the six- membered ring structure for the parent is proposed as precursor for the other ions. Appearance potentials were obtained for several product ions from deuterated benzenethiol, C/sub 6/H/sub 5/SD, and were used to determine heats of formation of the ions and establish processes by which they are formed. The parent ion is the only intermediate between the molecule, C/sub 6/H/sub 5/SD, and the product ions at m/e = 34, 45, 46, 67, 77, 84, 85, and 109. A proposed process for the formation of each of the ions is discussed. When ring cleavage of the parent ion takes place, ring closure in one of the fragments also takes place. (auth)