On the Relation Between Reactivity and Selectivity

Can one relate in a systematic fashion changes in the nature of the reactants to changes in the magnitude of the reaction rate constant? It is suggested that such correlations can be given a precise meaning and that the inverse correlation high selectivity—low reactivity is indeed valid. What need not always be true is that a single selectivity index (e.g., location of the transition state) suffices to quantitatively describe the correlation. When a single selectivity index does suffice we prove the reactivity—selectivity principle including the Hammond postulate.