[1] C. A. 14, 3500 (1920).
[2] J. Am. Pharm. Assoc. 11, 599 (1922).
III
BENZYL CYANIDE
C6H5CH2Cl + NaCN—> C6H5CH2CN + NaCl
Prepared by ROGER ADAMS and A. F. THAL Checked by O. KAMM and A. O. MATTHEWS.
1. Procedure
IN a 5-l. round-bottom flask, fitted with a stopper holding a reflux condenser and separatory funnel, are placed 500 g. of powdered sodium cyanide (96-98 per cent pure) and 450 cc. of water. The mixture is warmed on a water bath in order to dissolve most of the sodium cyanide, and then 1 kg. of benzyl chloride (b. p. 170-180'0) mixed with 1 kg. of alcohol is run in through the separatory funnel in the course of one-half to three-quarters of an hour. The mixture is then heated with a reflux condenser on the steam bath for four hours, cooled and filtered with suction to remove most of the sodium chloride. It is well to wash the filtered salt with a small portion of alcohol in order to remove any benzyl cyanide which may have been mechanically held. The flask is now fitted with a condenser, and as much alcohol as possible is distilled off on the steam bath. The residual liquid is cooled, filtered if necessary, and the layer of benzyl cyanide separated. This crude benzyl cyanide is now placed in a Claisen distilling flask and distilled in vacuo, the water and alcohol coming over first, and finally the cyanide. It is advantageous to use a fractionating column or, better still, a Claisen flask with a modified side-arm[1] (Vol. I, p. 40, Fig. 3) which gives the same effect as a fractionating column. The material is collected from 135-140'0/38 mm. (115-120'0/10 mm.). The yield is 740-830 g. (80-90 per cent of the theoretical amount).
[1] J. Am. Chem. Soc. 39, 2718 (1917). 2. Notes
The quality of the benzyl chloride markedly affects the yield of pure benzyl cyanide. If a poor technical grade is used, the yields will not be more than 60-75 per cent of the theoretical, whereas consistent results of about 85 per cent or more were always obtained when a product was used that boiled over 10'0. The technical benzyl chloride at hand yielded on distillation about 8 per cent of high-boiling material; a technical grade from another source was of unusual purity and boiled over a 2'0 range for the most part.