STUDIES IN CHEMICAL-IONIZATION .27. OXIDATION REACTIONS OF DIBENZOTHIOPHENE SUBJECTED TO NEGATIVE CHEMICAL-IONIZATION WITH OXYGEN

Dibenzothiophene (1) suffers surface-catalyzed oxidation under CI(O2) conditions. While in the positive mode M++ is the only major ion and t hose of the oxidation products are of minor importance in the negative mode, essentially only ions stemming from oxidized species can be see n, the sulfone ion [M + 02]-. being the most important one. The ion m/ z 184 previously attributed to M-. is actually the anion of 2-sulfoben zoic acid cyclic anhydride. Structures for the various oxidation produ cts are proposed and the mechanisms leading to their formation are dis cussed.