Studies in solvolysis. Part IX. Some commente on anion-cation combination reactions

The general validity of the Ritchie equation log (k n /k 0 ) = N + is evaluated on the basis of the bimolecular rate constants for various nucleophiles attacking crystal violet, malachite green, and the tris-p-anisylmethyl carbonium ion. A more general form of the Ritchie equation is required to accommodate the data viz. log (k n /k 0 ) = S + N + (S + = constant) for the most reactive carbonium ion. The latter modified form of the Ritchie equation is analogous to the Swain-Scott equation log (k 0 /k n ) = sn and the new form follows the usual relationship between reactivity and selectivity, i.e. the value of S + for the tris-p-anisylmethyl carbonium ion is less than unity.