Effect of substituents in phenol and aniline nucleophiles on activation parameters in SNAr reactions |
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Authors: | Vladislav M Vlasov |
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Institution: | N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation |
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Abstract: | Changes of activation parameters, ΔH≠ and ΔS≠, with σ constants of substituents in the phenol and aniline nucleophiles for their SNAr reactions in various solvents give the δΔH≠ and δΔS≠ reaction constants which are linearly related. The dependence obtained, δΔH≠ versus δΔS≠, allow estimation of the contribution of changes of the internal enthalpy, δΔH≠int, to the enthalpy reaction constant, δΔH≠, which give a linear dependence on the Hammett reaction constants, ρ. The results obtained show that the substituent effects on the charge development in the transition state (TS) are governed by the magnitude of δΔH≠int. Copyright © 2009 John Wiley & Sons, Ltd. |
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Keywords: | activation parameter substituent effect transition state charge development |
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