The photochemically induced reaction of sulfur dioxide with alkanes and carbon monoxide

Abstract— The gas phase photochemical reactions of SO₂ induced by 3130 Å radiation have been studied in the presence of added alkanes or added CO. The quantum yields obtained in the reactions with the low molecular weight alkanes employed are lower than those obtained by previous workers. The quantum yields were found to be pressure dependent increasing slowly with increasing pressure. A stoichiometric ratio of one SO₂ removed per molecule of hydrocarbon consumed was observed only under experimental conditions of [SO₂] < [RH]. For reaction mixtures where [SO₂] < [RH] the ratio of [SO₂]/[RH] reacted always exceeded unity. The quantum yields decreased slightly with increasing temperature. In all the alkane reaction systems studied, the deposition of viscous, nonvolatile reaction products was observed. In the experiments with added CO, the quantum yields were computed with respect to the rate of CO₂ formation. At 25°C and equal pressures of SO₂ and CO, φco₂ was observed to be 0.005 and it decreased slightly with increasing temperature. The results obtained are interpreted in terms of the sulfoxidation of the alkanes and the oxidation of CO proceeding by way of a ³SO₂ reaction intermediate.