The results of the reaction of an (OH)-O-. radical with a number of functio
nalized organic sulfides reported here demonstrate that the pH, the nature
of the functional group and the chain length affect the nature of the (OH)-
O-. radical reaction with sulfides. The transient absorption spectrum (lamb
da(max) = 295 nm), formed on reaction of H-. atoms and (OH)-O-. radicals wi
th an aqueous solution of 2-(methylthio)ethanol and 2-(ethylthio)ethanol is
assigned to the alpha-thio radical. It decayed by second order kinetics wi
th 2k = 5.2 x 10(9) dm(3) mol(-1) s(-1) and was quenched by oxygen. The tra
nsient absorption spectra (lambda(max) = 480 and 500 nm respectively), obta
ined on reaction with (OH)-O-. radicals (pH = 1), are assigned to a sulfur
centered dimer radical cation. The variation of the transient absorbance wi
th pH showed an inflection point at pH = 2.1. The reaction of (OH)-O-. radi
cals (pH = 6) with 2,2'-thiodiethanoyl chloride showed the formation of alp
ha-thio radicals (lambda(max) = 300 nm) and an OH-adduct (lambda = 350-380
nm), whereas in acidic solutions, the transient spectrum (lambda(max) = 340
nm, tau = 0.8 mu s) is assigned to an intra-molecular radical cation with
a 4-membered ring configuration. The transient species (lambda(max) = 370 n
m, tau = 17 mu s) formed on reaction of (OH)-O-. radicals with a 3,3'-thiod
ipropionyl chloride is assigned to a 5-membered intra-molecular radical cat
ion and remained independent of pH. The OH-adduct (lambda(max) = 350 nm, pH
= 1 1) of 3,3'-thiodipropionamide is observed to undergo transformation to
an intra-molecular radical cation (lambda(max) = 370 nm). The transformati
on is not observed in acidic solutions and only an intra-molecular radical
cation (lambda(max) = 370 nm) is observed immediately after the pulse. The
contribution of alpha-thio radicals of 2,2'-thiodiethanamide decreased with
pH, and in neutral solutions (OH)-O-. radicals are observed to react mainl
y by (OH)-O-.-adduct formation whereas in acidic solutions (pH = 1), as int
ra-molecular radical cation (lambda(max),, = 335 nm) with a 4-membered ring
configuration is inferred to be the transient species.