Phenylacetic acid from Benzyl Cyanide [2]
In a silica basin of about 35 cm. diameter, a mixture of 2.5 kilos of benzyl cyanide [3] and 7.5 kilos of 70% sulfuric acid is warmed until a few
bubbles of gas appear. The heating is at once stopped, since a very vigorous action now ensues. As the vapors evolved are injurious to health, the
basin is covered when the reaction begins with a sliding cover from which the vapors can be led into water. As soon as the reaction ceases, the
product is poured upon crushed ice in a large, earthenware vessel. Crude phenyl acetic acid, contaminated on the surface with phenyl acetamide, is
precipitated on cooling. In order to remove the amide, the acid is dissolved in lukewarm dilute soda solution. The amide remains undissolved and can
be filtered off, while the phenyl acetic acid goes into solution as sodium salt and is reprecipitated in a sufficiently pure state by the addition of
dilute mineral acid. After drying it is acceptably pure. |
