Knowledge Bank

Reactions between ground state oxygen atoms and methanethiol, $CH3SH$, or methyl sulfide, $CH3SCH3$, have been observed in argon matrices using infrared spectroscopy. The reactions were initiated by visible (514.5 nm) photolysis of matrices containing ozone and the respective sulfur compounds. The methyl sulfide reaction was a straightforward addition of the oxygen atom to form dimethyl sulfoxide. Prolonged photolysis produced a number of weak bands attributed to dimethylsulfone, $CH3-SO2-CH3$. Methanethiol reactions with oxygen atoms produce a more complex result. Oxygen-18 enriched experiments revealed that the reaction product(s) contain only one oxygen atom. Group frequencies and isotopic shift data show that three distinct reaction products are formed, namely as (1) oxygen doubly bonded to sulfur, as in the methyl sulfide reaction, (2) oxygen singly bonded to carbon and sulfur, i.e., C-O-S, and (3) oxygen singly bonded to sulfur and hydrogen, i.e., S-O-H. These results will be compared to earlier work from this laboratory in which oxygen atom reactions with $H2S$ yielded only hydrogen thioperoxide, HSOH.