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Issue 8, 1999
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Investigations on the nature and redox properties of the transients formed on pulse radiolysis of aqueous solutions of 2-(phenylthio)ethanol

Abstract

The radical cation of 2-(phenylthio)ethanol (PTE)+, generated on reaction of specific one-electron oxidants Cl2-, Tl2+, SO4-, CCl3OO, Br2-, by pulse radiolysis in aqueous solutions of PTE exhibits absorption bands at 315 and 530 nm. Pulse radiolysis of PTE in 1,2-dichloroethane also produced a similar transient absorption spectrum. The hydroxyl radicals are observed to react with a bimolecular rate constant of 7.5×109 d mol-1 s-1 and form absorption bands at 300, 365 and 530 nm. While the 530 nm band decayed by first order kinetics with k=2.1×104 s-1, other bands showed mixed kinetics. O- reacts exclusively by H atom abstraction forming a transient absorption band in 290–330 nm region, H reacts both by H abstraction and H-adduct formation. Based on these studies, OH radicals are inferred to react by electron transfer, H abstraction and OH-adduct formation. The radical cation reacts with electron donors, I-, N3-, with a high rate constant value. In neutral solutions, eaq- reacts with a bimolecular rate constant of 7.1×108 d mol-1 s-1 and the transient absorption band at 360 nm (ε=1.4×103 d mol-1 cm-1) is assigned to H-adduct formed on protonation of radical anion (pKa=7.9). In basic solutions, the radical anion has very small absorption at 360 nm (ε=0.6×103 d mol-1 cm-1). The radical anion formed on reaction of eaq- with PTE at pH 12 is able to transfer an electron to MV2+ whereas at neutral pH, electron transfer is not possible. The reduction potential for the PTE/PTE- couple is determined to be -1.23 V.

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Article information


Phys. Chem. Chem. Phys., 1999,1, 1919-1926
Article type
Paper

Investigations on the nature and redox properties of the transients formed on pulse radiolysis of aqueous solutions of 2-(phenylthio)ethanol

V. B. Gawandi, H. Mohan and J. P. Mittal, Phys. Chem. Chem. Phys., 1999, 1, 1919
DOI: 10.1039/A809900F

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