Kinetic Studies of Solvolysis. XIV. The Solvolysis of Optically Active α-Phenylethyl Chloride in Binary Mixtures of Methanol and Phenol —The SN1 Methanolysis with the Retention of the Configuration—

Abstract

Abstract The competitive SN1 methanolysis and SN1 phenolysis of optically-active α-phenylethyl chloride in the presence of added triethylamine give α-phenylethyl methyl ether and α-phenylethyl phenyl ether, both with a net inverted configuration, in 50 wt% methanolic phenol, whereas in 85–95 wt% methanolic phenol both the methyl and the phenyl ether have been obtained with a net retained configuration. In the intermediate solvent range (e.g., 75 wt% methanolic phenol), the methyl ether possesses a net inverted configuration, while the phenyl ether has a net retained configuration. Over the entire solvent range examined, the o- and p-α-phenylethylphenols (the C-alkylation products) possess net inverted configurations. This heretofore unusual retained steric course of the methanolysis is explained by the SNi-like four-center attack of a methanol molecule from the retentive side of the SN1 ion-pair intermediate. Much as in the retentive hydrolysis in the aqueous phenols, the specific solvation of the phenol molecules to the SN1 ion-pair intermediate may be suggested as a factor which assists the retentive attack of the methanol molecule.