Chemical reactivity of sulphur dioxide with unsaturated drying oils

Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the chemical reaction occurring between sulphur dioxide (SO 2 ) and unsaturated drying oils present in typical alkyd paints. Specifically, linolenic acid, linoleic acid, and oleic acid were studied. It was found that prior exposure of linolenic and linoleic acids to SO 2 would suppress the DSC exotherm associated with the autooxidative crosslinking reaction. Similar behavior had been noted previously when a fully formulated alkyd paint was exposed to SO 2 and then scanned in the DSC. Oleic acid was unreactive toward SO 2 , due to the lack of any doubly activated allylic hydrogen atoms (...)