Interaction of hydroxycinnamic acid derivatives with the Cl3COO radical: Apulse radiolysis study

The electron transfer reactions between the trichloromethylperoxyl radical (Cl3COO.) and hydroxycinnamic acid derivatives, including chlorogenic acid, sinapic acid, caffeic acid, ferulic acid and 3,4-(methylenedioxy)cinnamic acid, have been studied by pulse radiolysis. The hydroxycinnamic acid deriv atives, especially sinapic acid, are identified as good antioxidants for re duction of Cl3COO. via electron transfer reactions. From buildup kinetic an alysis of phenoxyl radical, the rate constant for reaction of Cl3COO. with sinapic acid has been determined to be 8.2 x 10(7) dm(3) mol(-1) s(-1), whi le the rate constants of electron transfer from other hydroxycinnamic acid derivatives to Cl3COO. were obtained to be about 2 x 10(7) dm(3) mol(-1) s( -1). The reaction of 3,4-(methylenedioxy) cinnamic acid with Cl3COO. was in vestigated as an evidence for the electron transfer mechanism.