Intramolecular van der Waals-London Cohesions and Chemical Reactivity: The Transition State in the Bimolecular Nucleophilic Displacement Reaction of Halide Ion with Alkyl Halide

Abstract

The intramolecular London-van der Waals cohesions in the transition states Hal^½-. . . CH₃ . . . Hal^½- in which both halogen atoms are identical should be greater than the following : Hal=F, 0.09 ; Hal=Cl, 0.6₄ ; Hal=Br, 0.9₄ ; Hal=I, 1.1₅ kcal/mole. It is concluded that these cohesions make a significant contribution to the observed increase in the velocity of the above displacement reaction as the polarizability of either entering or leaving halogen atom increases.