Investigations on the nature of the transient species formed on pulse radiolysis of a aqueous solution of 4-(methylthio)benzoic acid

The transient absorption spectrum ( ̧max D 320, 400 and 550 nm) obtained on reaction of OH radicals with 4-(methylthio)benzoicacid is assigned to a solute radical cation with a positive charge on the benzene ring. The reaction with speciŽ c one-electron oxidants also produced similar spectrum and the oxidation potential for the formation of solute radical cation is estimated to be between 1.4 and 1.6 V vs NHE. The reaction of eaq with the solute showed the formation of a transient absorption band at 320 nm and is assigned to solute radical anion with reduction potential more negative than¡1.5 V.