Chapter 2 Linear Free Energy Relationship and Kinetic Isotope Effect

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

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

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)

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

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

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

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