SUBSTITUENT EFFECT STUDIES OF ARYL-ASSISTED SOLVOLYSES .2. THE ACETOLYSIS OF 2-PHENYL-2-(SUBSTITUTED PHENYL)ETHYL P-TOLUENESULFONATES

The substituent effect on the acetolysis of 2-phenyl-2-(substituted phenyl)ethyl p-toluenesulfonates had a nonlinear LArSR correlation and was explicable in terms of a competitive aryl-assisted mechanism involving the X-substituted phenyl-assisted (k(M)X) pathway and the unsubstituted phenyl-assisted (k(N)X) pathway. By the application of the iterative nonlinear least-squares method based on the LArSR Eq., the substituent effect on the overall k(t) was dissected into the best-fit k(M) correlation of rho(M) = -3.53 with r(M) = 0.60, and the k(N) correlation of rho(N) = -0.88 with sigma0. The rho(M) and r(M) values for the effects of assisting aryl substituents are quite close to those of the 2-methyl-2-phenylpropyl system and the small rho(N) value with unexalted sigma0 constant for the unassisting aryls is compatible to the remote beta-aryl effect. The relative rates of competing pathways dissected based on the substituent effect analysis agreed completely with the ratio of respective aryl migration products determined by the C-13-tracer method. Exact rate-product correlation demonstrates that this system involves two discrete aryl-assisted pathways, k(M)X and k(N)X, which do not cross over.