CHARACTERIZATION OF TRANSIENTS FORMED IN AQUEOUS-SOLUTIONS OF SUBSTITUTED ALKYL SULFIDES - A PULSE-RADIOLYSIS STUDY

The transient optical absorption band (lambda(max) = 340 nm) formed on reaction of OH radicals with substituted alkyl sulfides, S(CH2CO2R)2, R = CH3, C2H5, C3H7, C4H9 in neutral aqueous solutions has been assig ned to the OH adduct. The yield, lifetime and molar absorption coeffic ient of this band is found to decrease with increasing chain length of R. The OH adduct of S(CH2CO2CH3)2 is able to undergo an electron tran sfer reaction with Br-, I- and SCN-. In acidic solutions, dimer radica l cations are formed at high solute concentration. The observed rate c onstant for the decay of dimer radical cations is deconvoluted to diff erent processes and the deprotonation is found to be the rate-determin ing step. The yield and lifetime are found to decrease with increasing chain length of R. The high concentration of acid required for their formation is discussed. Cl2.- and SO4.- are able to undergo one-electr on transfer reactions with S(CH2CO2CH3)2 with rate constants of 1.9 x 10(9) and 1.4 x 10(10) dm3 mol-1 s-1, respectively. The dimer radical cation is found to be a strong oxidizing agent and is able to oxidize Br- with a rate constant of 2.2 x 10(9) dm3 mol-1 S-1.