Reduction Potentials of Naphthoxyl and Pyridoxyl Radicals in Aqueous Solutions

Published

June 19, 1998

Author(s)

T N. Das, Pedatsur Neta

Abstract

Reduction potentials of 1- and 2-naphthoxyl, 2-, 3-, and 4-pyridoxyl, and 4-phenylphenoxyl radicals in alkaline aqueous solutions were determined by pulse radiolysis. The potential of 1-naphthoxyl was determined to be 0.59 V vs. NHE from the redox equilibrium involving 1-naphthol, 3-methylphenol, and their radicals. The reduction potential of the 3-methylphenoxyl radical (0.73 V) was obtained from its equilibrium with the phenoxyl radical. The potential for 2-naphthoxyl (0.71 V) was obtained from equilibrium with the phenoxyl radical. The reduction potentials of the three pyridoxyl radicals were measured from the equilibria with the 4-cyanophenoxyl radical. The values were found to be 1.18 V for 2-pyridoxyl, 1.06 V for 3-pyridoxyl, and 1.24 V for 4-pyrodoxyl. The reduction potential of 4-phenylphenoxyl radical (0.93 V) was obtained from equlibrium with the I₂.^- radical. From these reduction potentials and the known pK_a values of the phenolic compounds we estimated the O-H bond dissociation energies.

Citation

Journal of Physical Chemistry

Volume

102

Issue

35

Pub Type

Journals

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Keywords

naphthols, naphthoxyl, pulse radiolysis, pyridols, pyridoxyl, reduction potentials

Citation

Das, T. and Neta, P. (1998), Reduction Potentials of Naphthoxyl and Pyridoxyl Radicals in Aqueous Solutions, Journal of Physical Chemistry, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=831498 (Accessed October 11, 2025)