Mechanism and Kinetics of the Photocatalyzed Oxidation of p-Phenylenediamines by Peroxydisulfate in the Presence of Tri-2,2'-bipyridylylruthenium(II)

Abstract

The autocatalytic oxidation ofp-phenylenediamines with peroxydisulfate can be strongly enhanced by irradiation in the presence of tri-2,2’-bipyridylylruthenium(II). R~( b p y ) 3~a+ct s as photosensitizer and photocatalyst. First, R~( b p y ) 3~is+ fo rmed by quenching excited R~*(bpy)3~w+it h S 2 0 ~ ~ T- .h en the ruthenium(II1) complex oxidizesp-phenylenediamine. The resulting R~( b p y ) 3~ca+n start the cycle again. The photocatalytic oxidation of N,N-diethyl-p-phenylenediaminea s well as the dark reactions were studied with stopped-flow techniques. The mechanism of this complex reaction is discussed in detail.