Diphenyl (CAS NO.: ), which is known as Acetonitrile, diphenyl-, could be produced through the following synthetic routes.

A. α-Bromo-α-phenylacetonitrile (CAS NO.: ). In a well-ventilated hood, a dry 500-ml. round-bottomed three-necked flask is equipped with a sealed stirrer, an air condenser, and a cork carrying a dropping funnel and a thermometer. In the flask is placed 117 g. (1 mole) of benzyl cyanide. The thermometer is adjusted so that the bulb is immersed in the benzyl cyanide. The flask is placed in a bath and heated to 105–110° (inside temperature). With good stirring, 176 g. (1.1 moles) of bromine is added over a period of 1 hour; during the addition and for 15 minutes thereafter the temperature of the liquid is maintained at 105–110°. At the end of the heating period the evolution of hydrogen bromide gas has practically ceased. The dropping funnel is replaced by a cork carrying a glass tube reaching to within 2–3 cm. of the surface of the reaction mixture. Dry nitrogen is then led through the apparatus for 30 minutes. The hot mixture is poured into the 500-ml. addition funnel fitted to the apparatus to be used in the next step (see part B). The reaction flask is rinsed with 100 g. (1.3 moles) of dry benzene, and this is added to the bromonitrile. The benzene solution thus obtained is used immediately in the next step.

B. (CAS NO.: ). A dry 2-l. round-bottomed three-necked flask, equipped with a sealed stirrer, a 500-ml. dropping funnel, and a dry reflux condenser, is mounted on a steam bath. In the flask are placed 368 g. (4.7 moles) of dry benzene 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. 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 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).