The Electrophile Desolvation Process in Nucleophile - Electrophile Combination Reactions *

where k is the rate constant for a reaction of an electrophile with a given nucleophilic system, k 0 is dependent solely on the identity of the electrophile and N + is a parameter characteristic of the nucleophilic system. The most surprising result of this relation is its incompatibility with the reactivity-selectivity principle, because, since N + is independent of the electrophile, the relative reactivity of different electrophiles with a given nucleophilic system is constant and independent of said nucleophilic system, which implies that the selectivity of these kinds of reactions do not depend on their reactivity. To explain this fact, Ritchie concluded that there are not specific interactions between electrophile and nucleophile at the transition state, and that electrophile desolvation has not begun. On the contrary, Pross showed that experimental data could be interpreted much better by supposing that the electrophile had undergone partial desolvation at the transition state; the less extensive this desolvation the stronger the electrophile. Introducing the assumpti-0n that the degree of electrophile desolvation at the transition state is dependent