Abstract
The Alkyl-Oxygen fission of Carboxylic Esters. Reactions of p-Methoxybenzhydrol and some of Its Esters. The object of the present investigation is to show that although alkyl-oxygen fission in carboxylic esters denoted by the mechanism is unusual, it is by no means rare, especially when the group R has electron-releasing properties. The following secondary alcohols and their hydrogen phthalic esters have been prepared. p-Methoxybenzhydrol o-Methoxybenzhydrol a-Methyl anisyl alcohol Phenyl methyl carbinol a-Methyl piperonyl alcohol a-Phenyl piperonyl alcohol Of these alcohols p-methoxybenzhydrol is the most satisfactory from the experimental point of view, as it is crystalline, and can readily be resolved into its optically active forms. The reactions of this alcohol and several of its esters are described in considerable detail. The preparation of dextrorotatory p-methoxybenzhydrol, and the optically active acid phthalic esters of a-methyl anisyl alcohol and phenyl piperonyl carbinol is also described. Alkyl-oxygen fission occurs very readily with esters of p-methoxybenzhydrol, a-methyl anisyl alcohol and to a less extent with those of phenyl methyl carbinol. In the case of p-methoxybenzhydrol and -methyl anisyl alcohol it Is presumably the powerful electron-releasing effect of the p-methoxyl group which causes alkyl-oxygen fission to occur so readily under appropriate conditions. The esters of o-methoxybenzhydrol, methyl and phenyl piperonyl carbinols also show alkyl-oxygen fission, particularly in their reactions with sodium p-toluene sulphinate and with dilute aqueous sodium hydroxide. The resolution of propenylethinyl carbinol is described. The acid phthalio ester of this alcohol is readily resolved into the d- and the l - form by means of cinchonidine in ethyl acetate solution.