Bulletin of the Korean Chemical Society

Korean Chemical Society (대한화학회)
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Kinetic Studies on the Reduction of 1-Benzyl-3-cyanoquinolinium Cations by Sodium Borohydride and the Applicability Marcus Theory

  • Han, In-Sook (Department of Science Education, Kangweon National University) ;
  • Lee, Chang-Kiu (Department of Chemistry, Kangweon National University) ;
  • Han, In-Sup (Department of Chemistry, Kangweon National University)
  • Published : 1987.04.20
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Abstract

The reduction of a series of 1-substituted benzyl-3-cyanoquinolinium ions (p-$cH_3$, H, p-Br, m-F, p-CN) by sodium borohydride has been investigated. In all cases the products from these reactions were found to be 1, 2-dihydroquinolines over 82% yields. Rates of reduction were measured in basic condition and in solvent system consisting of 4 parts of isopropyl alcohol and 1 part of water by volume. Second order rate constants were obtained for these reactions. When the ratio of [$OH^-$] to [$BH_4^-$] becomes large the observed rate constants ($K_{obs}$) decrease by a small factor. Reaction scheme and rate law are discussed. Bronsted ${\alpha}(=\frac{d\;In\;k}{d\;In\;K})$ obtained by using the value of equilibrium constant K, which was obtained previously, was not 0. Instead, a value of 0.36 was obtained which indicated that the reduction by borohydride was structure-dependent according to the Marcus formalism even though the reaction rate was close to the diffusion limit.

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References

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