Phenylcyclohexylcarbinol: Some Reactions of the Optically-Active Alcohol and its Derivatives.

(1) Recent theories of the nature of optical rotatory power are reviewed with special reference to those of Kuhn and Born, and the chemical implications of the quantum-mechanical treatments of Kirkwood and of Condon, Eyring and co-workers. The importance of Kuhn's vicinal effect in systematic studies of the relation between chemical structure and optical rotatory power, and the relation between selective absorption and rotatory dispersion, are discussed. (2) Methods are presented for the complete resolution of phenylcyelohexylcarbinol and the preparation of several optically-active derivatives. Some simple kinetic studies of these preparative reactions are discussed in the light of current views on the mechanisms of reactions of this type. (3) Ultraviolet absorption spectra are presented for phenyl- cyclohexylcarbinol and five derivatives. These are interpreted on the basis of established correlations between ultraviolet absorption and chemical structure. In all the compounds examined the principle chromophore is the phenyl group of the carbinol. (4) The rotatory dispersions of phenylcyclohexylcarbinol and several derivatives in a variety of solvents are expressed in the form of one-term two-constant Drude equations. These are used, in conjunction with ultraviolet absorption data, to iden- tify the groups from which the first (long-wave) optically-active absorption bands originate. Experimental evidence and simple theoretical arguments both show that the vicinal effects of the n-hexyl, cyclohexyl and phenyl groups, when two are attached to the same asymmetric centre, are not identical as was suggested by Kuhn. (5) Racemisation measurements on optically-active phenylcyclo- hexylearbinyl acetate and formate by an alkyl-oxygen fission process in several solvents, notably acetic and formic acids, are given in the form of first-order rate constants. Compari-son with similar data for l-naphthylmethylcarbinyl and phenyl -methylcarbinyl esters indicate that promotion of alkyl-oxygen fission of the esters by electron release from the carbinyl group is slightly less in phenyleyclohexylcarbinol than in phenylmethylcarbinol. This difference is correlated with other characteristics of the cyclohexyl group related to its electron-release tendency. In agreement with these results the optically-active hydrogen phthalate of the carbinol undergoes alkaline hydrolysis to the carbinol without racemisation under a variety of experimental conditions