Studies of the reactions of anhydrosulphites of α-hydroxycarboxylic acids. Part VI. Anhydrosulphite synthesis and characterisation

Abstract

The reaction of thionyl chloride with α-hydroxycarboxylic acids has been studied under conditions which favour anhydrosulphite formation. The most important impurity is shown to be the appropriate α-chloroacid chloride. The removal of this species is essential for controlled polymerisation of the anhydrosulphite, and is best achieved by chemical rather than physical methods. Physical data and characteristic spectral features of the ring are presented for several purified anhydrosulphites.