4. The procedure from this point on can be simplified and improved as follows. After the addition of water to the
aluminum chloride complex,
100 cc. of concentrated hydrochloric acid (sp. gr. 1.18) is added and the
benzene is removed by steam distillation. The hot mixture is transferred to a
1-l. beaker, and the
β-benzoylpropionic acid separates as a colorless oil which soon solidifies. After cooling to 0°, it is collected, washed with a cold mixture of
50 cc. of concentrated hydrochloric acid and 150 cc. of water, and then with 200 cc. of cold water. The crude acid is dissolved in a solution of
75 g. of anhydrous sodium carbonate in 500 cc. of water by boiling for fifteen minutes. The solution is filtered by suction and the small amount of
aluminum hydroxide washed twice with 50-cc. portions of hot water. Four grams of charcoal is added to the hot filtrate; the solution is stirred for three to four minutes and then filtered with suction. The clear, colorless filtrate is transferred to a 2-l. beaker, cooled to 50–60°, and carefully acidified with
130 cc. of concentrated hydrochloric acid. After cooling to 0° in an
ice-salt bath the acid is filtered, washed well with water, dried overnight at room temperature, and finally dried to constant weight at 40–50°. The yield is
110–115 g. (
92–95 per cent of the theoretical amount). It melts at
114–115° and needs no further purification. (E. L. Martin and Louis F. Fieser, private communication.)
7. By evaporating the filtrate to a small volume and extracting with
ether, a further 3 g. of acid may be obtained.