Abstract
The reversibility of the benzoin condensation was demonstrated for the first time by Anderson and Jacobson at the University of Nebraska. They obtained benzaldehyde by reacting pure benzoin with sodium cyanide in a 95 ethyl alcohol solution. The benzaldehyde was recovered by ether extraction, and identified by conversion into benzal-phenylhydrazone. The ether extract on fractional distillation gave very little indication of the presence of benzyl alcohol. These investigators also determined the equilibrium constant for the reaction, |2C6H5CHO <- -> C6H5CHOHCOC6H5, |at approximately 79° C. in a 95 % ethyl alcohol solution. In this work, the weight of benzaldehyde present at equilibrium was taken as the difference between the weight of benzaldehyde or benzoin used and the benzoin found after equilibrium had been reached. Some of the experiments were performed in an atmosphere of nitrogen in order to prevent the oxidation of the benzaldehyde. The equilibrium constant found in using an atmosphere of nitrogen varied considerably from the constant found when the experiments were carried out in an atmosphere of air.