To a solution of 100 g. (2.0 moles) of 98% sodium cyanide in 400 ml. of water, contained in a 3-l. round-bottomed flask fitted with a Hershberg stirrer, is added 118 g. (2.2 moles) of ammonium chloride. The mixture is stirred at room temperature under a properly ventilated hood. When the ammonium chloride has dissolved, a solution of 212 g. (2.0 moles) of benzaldehyde in 400 ml. methanol is added in one portion. The reaction begins rapidly, the temperature rising to about 45°. Stirring is continued for 2 hours. The heterogeneous mixture, after dilution with 1 l. of water, is extracted with 1 l. of benzene, and the aqueous layer is discarded. The benzene layer is washed with three 50-ml. portions of water, and the aminonitrile is extracted, in the form of its hydrochloride, by shaking the benzene solution with 6 N hydrochloric acid, first with one 600-ml. portion and then with two 300-ml. portions.

The combined acid extracts are placed in a 3-l. round-bottomed flask and refluxed for 2 hours (Note 1). The hydrolysate is diluted with water to bring its volume to about 2 l. and is then subjected to distillation under reduced pressure (20–30 mm.) to remove all benzaldehyde and other volatile substances (Note 2). To remove some resinous matter deposited in the course of the hydrolysis, the mixture is treated with 10 g. of Norit and filtered through a Büchner funnel. The yellow filtrate is transferred to a 3-l. beaker. It is stirred by hand with a thick glass rod while ammonium hydroxide (sp. gr. 0.90) is added through a dropping funnel until the liquid is faintly alkaline to litmus (Note 3). The mixture becomes quite hot and acquires a strong odor of benzaldehyde. The amino acid separates in the form of yellow crystals. The mixture is cooled to room temperature, and the crystals are collected on a 15-cm. Büchner funnel. After washing with about 1 l. of water in small portions to remove the ammonium chloride, the solid is washed successively with 150 ml. of ethyl ether, three 50-ml. portions of hot 95% ethanol, and finally with about 500 ml. of water. The crystals, when dried by suction, weigh 220 to 240 g. (Note 4). Drying is completed in a vacuum desiccator over phosphorus pentoxide. The yield of crude amino acid is 102–116 g. (34–39%).

For purification, the product is dissolved in 800 ml. of 1 N sodium hydroxide, 500 ml. of ethanol is added, and the solution is filtered. The filtrate is transferred to a 2-l. beaker and is heated to the boiling point. Then 160 ml. of 5 N hydrochloric acid is slowly added, through a dropping funnel, while stirring by hand. The mixture is cooled to room temperature and is filtered with suction. The product is washed with 100 ml. of ethanol, then with 200 ml. of water, and is dried in a vacuum desiccator over phosphorus pentoxide. The nearly white, lustrous platelets have no definite melting point (Note 5). The yield of pure amino acid is 98–112 g. (33–37%) (Note 6).