Preparation of phosphorus tribromide
phosphorus tribromide: A 500 ml three-necked flask, fitted with a mechanical stirrer, a dropping funnel and a reflux condenser, 28 grams of pure red phosphorus, and 200 ml of dry carbon tetrachloride (dried over anhydrous calcium chloride) are placed. 198 grams (or 63.5 ml) of dry bromine are placed in the dropping funnel and added to the vigorously stirred mixture of red phosphorus in tetrachloromethane at the rate of about few drops per second.
After all the bromine has been added, the reaction mixture is refluxed for 15 minutes at 80-90° C. The clear solution is then decanted (if necessary filtered) and the carbon tetrachloride is removed by distillation. The crude phosphorus tribromide is purified by distillation through the efficient column, by collecting fraction boiling at 166-169° C (mainly at 168° C). Phosphoras tribromide is additionally purified by redistillation and collecting fraction boiling at 170-171° C. The yield of phosphorus tribromide is 190 g.
A text book of practical organic chemistry, by A. I. Vogel, 189-190, 1974
