1,2- and 1,4-Diacetoxylation of 1,3-butadiene via 2,5-dihydrothiophene 1,1-dioxide as a probable intermediate

Sulphur dioxide has been found to promote a novel liquid-phase oxidation of 1,3-butadiene in acetic anhydride with oxygen gas and catalytic amounts of concentrated protic acids (e.g. hydrobromic acid). 1,2-Diacetoxy-3-butene and 1,4-diacetoxy-2-butene together with small amounts of 1-hydroxy-2-acetoxy-3-butene and 1-hydroxy-4-acetoxy-2-butene are formed in the reaction.