Radically different antioxidants: thermally generated carbon-centered radicals as chain-breaking antioxidants.

A new class of thermally activated chain-breaking antioxidants is presented. Dimers of persistent carbon-centered radicals are able to inhibit the autoxidation of cumene and styrene with better rate constants than the commercial antioxidant Irganox HP-136 and 3,5-di-tert-butyl-4-hydroxyanisole. A dramatic increase in antioxidant activity is observed with increasing temperature as more dimers dissociate to their corresponding persistent radicals.