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Chapter 2 Linear Free Energy Relationship and Kinetic Isotope Effect

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Presentation on theme: "Chapter 2 Linear Free Energy Relationship and Kinetic Isotope Effect"— Presentation transcript:

1 Chapter 2 Linear Free Energy Relationship and Kinetic Isotope Effect

2 Substituent Effects Field effects Inductive effects Resonance effects
Polarizability effects Steric effects Solvation effects

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4 Hammett Plots-- a general method for examining changes in charges during a reaction.
Sigma values KX s = log (KX/KH)

5 Hammett Plots sr = log (KX/KH) sr = log (kX/kH) Rho values
When r>1< the reaction under study is more sensitive to substitents than benzoic acid, and negative charge is building during the reaction. When 0<r<1, the reaction is less sensitive to substituents than benzoic acid, but negative charge is still building When r is equal to or close to 0, the reaction shows no substituent effects. When r is negative, the reaction is creating positive charge. sr = log (KX/KH) sr = log (kX/kH)

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9 P. Jr. Wentworth, A. Datta, S. Smith, A. Marshall, L. J. Partridge,
and G. M. Blackburn, J. Am. Chem. Soc., 1997, 119, 2315

10 J. P. Richard, and W. P. Jencks, J. Am. Chem. Soc.,
1982, 104, 4689.

11 J. Lehman, and G. C. Lloyd-Jones, Tetrahedron, 1995, 8863

12 Kinetic Isotope Effect
Stretching vibration Bending vibration n m-1/2 m: reduced mass

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