Electron transfer from the benzophenone ketyl radical anion to 9,10-anthraquinone-2-sulphonate and methylviologen in water—propan-2-ol mixtures

https://doi.org/10.1016/1010-6030(88)85002-0Get rights and content

Abstract

The electron transfer reaction between the benzophenone ketyl radical anion ((C6H5)2CO−radical dot and (i) the 9,10-anthraquinone-2-sulphonate anion (AQS) and (ii) the methylviologen cation (MV2+) was studied in a 1:1 (v/v) water—propan-2-ol mixture using the technique of flash photolysis. The kinetics of the formation of the respective products 9,10-anthraquinone-2-sulphonate radical anion (AQS−radical dot) and the methylviologen radical cation (MV+radical dot) were analysed by using the Runge—Kutta fourth-order numerical solution for the system of differential equations that pertain to the proposed kinetic scheme. Equilibrium constants for the reactions (C6H5)2CO−radical dot + AQS ⇌ (C6H5)CO + AQS−radical dot and (C6H5)2CO−radical dot + MV2+ ⇌ (C6H5)2CO + MV+radical dot were determined to be K1 = 2.7 X 103 and K2 = 1.9 X 104 respectively. The rates of the forward reactions were found to be 104 - 105 times slower than the rates reported in water-acetonitrile mixtures. It was also observed that the production of AQS−radical dot and MV+radical dot radicals continued for a considerable time after the complete decay of the benzophenone ketyl radical anion. The results suggest that this process involves the reaction between AQS or MV2+ and benzopinacol, a product of the photolysis.

References (29)

  • J.C. Scaiano et al.

    Chem. Phys. Lett.

    (1981)
  • M.B. Rubin

    Tetrahedron Lett.

    (1982)
  • S. Baral-Tosh et al.

    J. Phys. Chem.

    (1984)
  • K. Chandrasekaran et al.

    J. Am. Chem. Soc.

    (1981)
  • P. Hyde et al.

    J. Chem. Soc., Perkin Trans. II

    (1974)
  • H. Hayashi

    Bull. Chem. Soc. Jpn.

    (1980)
  • J.R. Brandon et al.

    J. Chem. Phys.

    (1970)
  • M.Z. Hoffman et al.

    Radiat. Phys. Chem.

    (1984)
  • C.K. Grätzel et al.

    J. Am. Chem. Soc.

    (1979)
  • A. Harriman

    J. Chem. Soc., Faraday Trans. II

    (1986)
  • C. Reichardt
  • O.I. Micic et al.

    J. Phys. Chem.

    (1974)
  • K.J. Nielsen
  • K.J. Johnson
    • View full text
    Copyright © 1988 Published by Elsevier B.V.