Spectral, kinetics, and redox properties of the transients formed on one-electron oxidation of 4,4 '-thiodiphenol: A pulse radiolysis study

The transient absorption bands (lambda(max) = 330, 525 nm, k(f) = 5 X 10(9) dm(3) mol(-1) s(-1)) Obtained on pulse radiolysis of (NO)-O-2-saturated ne utral aqueous solution of 4,4'-thiodiphenol (TDPH) are due to the reaction of TDPH with (OH)-O-. radicals and are assigned to phenoxyl radical formed on fast deprotonation of the solute radical cation. The reaction of specifi c one-electron oxidants (Cl-2(.-), Br-2(.-), N-3(.), Tl2+, CCl3OO.) with TD PH also produced similar transient absorption bands. The phenoxyl radicals are also produced on pulse radiolysis of N-2-saturated solution of TDPH in 1,2-dichloroethane. The nature of transient absorption spectrum obtained on reaction of (OH)-O-. radicals with TDPH is not affected in acidic solution s, showing that OHadduct is not formed in neutral solutions. The oxidation potential for the formation of phenoxyl radical is determined to be 0.98 V. (C) 1999 John Wiley G Sons, Inc. Int I Chem Kinet 31: 603-610. 1999.