Ion—molecule reactions in hydrogen sulfide, methanethiol and 2-thiapropane

Abstract

The ion—molecule reactions in H 2S, CH 3SH, and (CH 3) 2S were observed at pressures up to 400 millitorr, using a quadrupole mass spectrometer with a single electron-impact ion source. Rate constants were measured for the disappearance of most primary ions and the appearance of several secondary ions, and mechanisms are proposed for the reactions observed. In all three cases, the major ion produced was the M + 1 ion (where M represents the mass of the parent ion), which reacted further to give the 2M + 1 ion. Charge exchange between the neutral gas and primary ions to produce the parent ion was observed in CH 3SH and (CH 3) 2S and is suspected in H 2S. In the cases of CH 3SH and (CH 3) 2S, an additional reaction sequence originating with the (M − 1) ion was observed, while in H 2S an additional sequence originating with the S + ion was found.