A tr esr study of the reactions of excited organic triplet molecules with inorganic sulfur oxoanions

Abstract

The reactions of excited triplet ketones including benzophenone, 4,4'dihydroxybenzophenone, and acetone with inorganic sulfur oxoanions: sulfite (SO 3 = ), metabisulfite (S 2 O 5 = ), and dithionite (S 2 O 4 = ) in solution were studied by TR ESR. Observation of radical anion intermediates polarized by the Triplet Mechanism demonstrated the reactions of electron transfer from the sulfur dianions to the organic triplet states. Thus, electron transfer from SO 3 = to the triplet organic carbonyl compounds gave rise to the SO 3 -* radical; reactions with metabisulfite and dithionite were more complex and may be interpreted as occurring via electron transfer to the carbonyl system followed by dissociation of the S-S bond in the resulting sulfur oxoanion radical. The initial radical ion pairs thus formed consist of pairs of anion radicals, one organic and one inorganic.