Retentive solvolysis. Part XI. Retentive phenolyses of optically active secondary and tertiary systems without a group imposing configurational restriction

Abstract

The rate, product distribution, and stereochemical course for phenolyses of 17 compounds, including three p-substituted 1-phenylethyl systems, eight m- or p-substituted 2,2-dimethyl-1-phenylpropyl systems, 1-phenylpropyl, 2-methyl-1-phenylpropyl, p-chlorodiphenylmethyl, and 1-methyl-1-phenylpropyl p-nitrobenzoate, and 1-ethyl-1,5-dimethylhexyl chloride and trifluoroacetate have been investigated. The titrimetric rate constants for p-substituted 1-phenylethyl p-nitrobenzoates and for m- or p-substituted 2,2-dimethyl-1-phenylpropyl p-nitrobenzoates follow the Yukawa–Tsuno correlation in pure phenol as solvent. All phenyl ethers, major products of phenolyses, show net retention of configuration: in particular, the extent of retention was 97.4% for 2,2-dimethyl-1-(p-nitrophenyl)propyl phenyl ether and 90.0% for 2,2-dimethyl-1-phenylpropyl phenyl ether in the presence of triethylamine. C-Alkylated products are formed to a small extent and show net inversion in ten phenolyses examined; among these, o- and p-(2,2-dimethyl-1-phenylpropyl) phenol which are produced from the p-nitrobenzoate show almost completely inverted configuration. Variations the polarimetric and titrimetric rates, in the product yield, and in the extent of retention have been examines for various concentrations of added base in the phenolyses of eight selected substrates. On the basis of these results, the mechanism and stereochemical course of the phenolyses are discussed by the use of a generalized scheme, previously proposed for the phenolyses of 1-phenylethyl systems. The maximum rotations and the absolute configurations of the compounds have been determined by chemical or n.m.r. shift reagent methods.