Determination of Rate Constants for Reactions of Bichloride Anion Radical with Some Dipeptides in Aqueous Solution of KCl and K2S2O8 by Flash Photolysis

Abstract

Abstract Determination of rate constants for reactions of dichloride anion radical was conducted by conventional flash photolysis of aqueous solutions of KCl and K2S2O8, where no participation of HOCL−· is expected in decay kinetics of dichloride anion radical. The optimum conditions found for the determination are 0.1 mol dm−3 KCl and 10−4 mol dm−3 K2S2O8. Under the present experimental conditions, S2O82− serves to convert chloride ion to dichloride anion radical through reaction with hydrated electron produced by photolysis of chloride ion. For glycyltryptophan, the competition method was employed, because its transient absorption overlaps the absorption due to dichloride anion radical. The rate constants determined are almost the same as those obtained in N2O-saturated aqueous solution of KCl (1 mol dm−3). The reactivity of dipeptides toward dichloride anion radical is discussed.