Kinetic Studies of Solvolysis. XIII. The Solvolyses of Optically-active α-Phenylethyl Chloride in Binary Mixtures of Phenol and Water—The Sn1 Hydrolysis with the Retention of the Configuration

Abstract

Abstract The competitive Sn1 hydrolysis and Sn1 phenolysis of optically-active α-phenylethyl chloride in aqueous phenols (75 to 90 wt% phenol) give partially-retained α-phenylethyl alcohol and α-phenylethyl phenyl ether in the presence of added triethylamine at 14 and 30°C. The extent of the retention of the configuration is almost independent of the reaction temperature, whereas it shows a tendency to increase from 13 to 23% for the alcohol and from 5 to 20% for the ether with an increase in the phenol concentration. A predominant four-center (Sni-like) attack of a water molecule, with the assistance of a specific solvation of phenol molecules, has been suggested as a possible interpretation for the unusual hydrolysis with a retained steric course for this simple secondary alkyl system. In connection with the nature of the specific solvation of phenol molecules, the applicability of the concept of the back-side shielding of the Sn1 ion-pair intermediate by a phenol molecule has been discussed.