Photochemical 2 + 2-cycloadditions of sulphur dioxide and ketenes in low-temperature matrices

Abstract

U.v. irradiation at 12 K of Ar or N₂ matrices containing ketenes and SO₂ yielded the corresponding 1,2-oxathietan-4-one 2-oxides as 2 + 2-cycloadducts; this reaction was shown to be distinct from the thermal 1 + 2-cycloaddition of ketene and SO₂. The 2 + 2-adducts decomposed on prolonged irradiation to CO₂, sulphur atoms, and the corresponding aldehydes or ketones, presumably via sulphines, which, however, could not be detected. Interpretation of the spectra was complicated by strong interactions between carbonyl compounds and SO₂, and this phenomenon was also explored.