B.
Diphenylacetonitrile. A dry
2-l. round-bottomed three-necked flask, equipped with a sealed stirrer, a
500-ml. dropping funnel, and a dry
reflux condenser (Note
2), is mounted on a
steam bath. In the flask are placed
368 g. (4.7 moles) of dry benzene (Note
5) and
133.5 g. (1 mole) of powdered anhydrous aluminum chloride. The stirrer is started, and the
benzene is heated to vigorous refluxing. The
α-bromo-α-phenylacetonitrile solution is added to the boiling mixture over a period of 2 hours in small portions (Note
7). After the addition is complete, the reaction mixture is refluxed for an additional hour. The flask is cooled, and the mixture is poured into a stirred mixture of 1 kg. of crushed ice and
100 ml. of concentrated hydrochloric acid in a
3-l. beaker.
The
benzene layer is separated. The aqueous layer is extracted with
500 ml. of ether in two equal portions. The
ether and
benzene solutions are combined and washed successively with 500 ml. of water,
250 ml. of saturated sodium bicarbonate solution, and 500 ml. of water. The organic layer is dried over
100 g. of anhydrous sodium sulfate. The drying agent is separated from the solution, and the solvents are removed by heating on a steam bath. The last traces of
benzene are removed by vacuum distillation from a
250-ml. Claisen flask heated on a steam bath. The residue weighs about 190 g. A receiver is connected directly to the side arm (Note
8) of the Claisen flask, and the product is distilled under reduced pressure. It boils at
122–125°/1–2 mm. and crystallizes to a yellow solid which melts at
68–70°. The solid is recrystallized from
isopropyl alochol (1 ml. per g.); the flask containing the filtered hot solution is placed on an asbestos mat, and the solution is allowed to cool only to room temperature without shaking or stirring. The crystals are then collected and washed on the funnel with chilled
isopropyl alcohol (one-fifth the volume used in the recrystallization). The product is dried in a
vacuum desiccator over concentrated
sulfuric acid or
phosphorus pentoxide. The yield of pure white product, melting at
74–75°, is
97–116 g. (
50–60% based on
benzyl cyanide) (Note
9).