Mechanisms of antioxidant action: the pro-oxidant stage in the function of thiodipropionate esters as antioxidants

The thermal decomposition of dimethyl sulphinyldipropionate alone and in the presence of 2,6-di-t-butyl-α-(3,5-di-t-butyl-4-oxo-2,5-cyclohexadiene-1-ylidene)p-tolyloxy (Galvinoxyl) was studied. Results show that radical intermediates capable of initiating oxidations are not produced under these conditions but radicals are formed from dimethyl sulphinyldipropionate in the presence of hydroperoxides. This reaction is probably responsible for the pro-oxidant effects associated with sulphoxides.