The kinetics of the reactions of three trans-dioxoruthenium(VI) porphyrin derivatives with organic sulfides were measured. These trans-dioxoruthenium(VI) species were competent oxidants and reacted rapidly with thioanisoles to generate corresponding sulfoxides. Typical second-order rate constants determined for sulfoxidation reactions are 8-60 M-1s-1, which are 3 orders of magnitude larger in comparison with those of well studied alkene epoxidations and activated C-H bond oxidations by the same dioxo species. Various para-substituted thioanisoles react in a narrow kinetic range with the same dioxo species. The kinetic results obtained in this study indicate a concerted oxygen atom transfer and/or electron transfer followed by oxygen transfer mechanism from oxidant to sulfide. Competition kinetic reactions with a catalytic amount of porphyrin ruthenium(II) species and a terminal oxidant give relative rate constants for sulfoxidation of competing substrates that are consistantly smaller than the ratios of absolute rate constants, implying a multiple oxidant model for sulfoxidation reactions.

Kinetic studies of oxygen atom transder reaction from trans-dioxoruthenium(VI) porphyrins to sulfides

243rd National Meeting (2012)

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