Pulse radiolysis study of some substituted thiophenols in aqueous solutions

Spectral and kinetic properties of the transient species formed by the reaction of substituted thiophenols such as 4-methyl thiophenol (MTP) and thiosalicylic acid (TSA) with e(aq)(-) H-atom, OH radicals and one electron oxidants, viz. N-3 and Br-2(-) radicals and one-electron reductants such as CO2H and CH3)(2)COH radicals have been studied by pulse radiolysis technique. One electron oxidation leads to the formation of phenylthiyl type of radicals (R6H4S.) OH radicals react with MTP by addition to the benzene ring as well as by one-electron oxidation to give both hydroxycyclohexadienyl type of radicals and CH3C6H4S. type radicals whereas in the case of TSA the 390 nm band which is due to the hydroxycyclohexadienyl type of radical was not observed. In acidic solutions H-atoms, COOH and (CH3)(2)COH radicals abstract H atom from the -SH group of MTP and produce a species which is identical to that obtained by OH radical reaction under the same conditions, thus acting as oxidants. Similar reactions were not observed in the case of TSA. The phenylthiyl type of radicals were found to be non-oxidising in nature. (C) 1999 Elsevier Science Ltd. All rights reserved.