Title: Chapter 2 Linear Free Energy Relationship and Kinetic Isotope Effect
1Chapter 2 Linear Free Energy Relationship and
Kinetic Isotope Effect
2Substituent Effects
- Field effects
- Inductive effects
- Resonance effects
- Polarizability effects
- Steric effects
- Solvation effects
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4Hammett Plots-- a general method for examining
changes in charges during a reaction.
KX
s log (KX/KH)
5Hammett Plots
sr log (KX/KH) sr log (kX/kH)
- Rho values
- When rgt1lt the reaction under study is more
sensitive to substitents than benzoic acid, and
negative charge is building during the reaction. - When 0ltrlt1, 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.
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9P. Jr. Wentworth, A. Datta, S. Smith, A.
Marshall, L. J. Partridge, and G. M. Blackburn,
J. Am. Chem. Soc., 1997, 119, 2315
10J. P. Richard, and W. P. Jencks, J. Am. Chem.
Soc., 1982, 104, 4689.
11J. Lehman, and G. C. Lloyd-Jones, Tetrahedron,
1995, 8863
12Kinetic Isotope Effect
- Stretching vibration
- Bending vibration
n m-1/2
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m reduced mass
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