Boron Trifluoride Catalyzed Hydrolysis of Nitriles

The hydrolysis of nitriles catalyzed by boron trifluoride is a reliable and high yield process for conversion to the corresponding amide. Other methods give variable yields and may result in a significant quantity of acid being formed, whereas the procedure given below frequently results in yields above 90%. 

A solution of 3 g of the nitrile, water (5 moles per mole of nitrile), and 20 g of boron trifluoride-acetic acid complex is heated (mantle or oil bath) at 115-120° for 10 minutes. The solution is cooled in an ice bath with stirring and is carefully made alkaline by the slow addition of 6 A sodium hydroxide (about 100 ml). The mixture is then extracted three times with 100-ml portions of 1 1 ether-ethyl acetate, the extracts are dried over anhydrous sodium sulfate, and the solvent is evaporated on a rotary evaporator to yield the desired amide. The product may be recrystallized from water or aqueous methanol. Examples are given in Table 7.1. 

---