To
68 g. (0.5 mole) of phenylacetic acid (Note
1) in a
1-l. flask fitted with a
reflux condenser and a system for absorbing
hydrogen chloride, is added
35 g. (0.25 mole) of phosphorus trichloride. The mixture is heated on a
steam bath for one hour. While the contents of the flask are still warm,
400 cc. of dry benzene is added. The
benzene solution of
phenylacetyl chloride is decanted from the residue of
phosphorous acid onto
75 g. (0.56 mole) of anhydrous aluminum chloride in a dry, 1-l. flask which can be fitted to the same condenser. The reaction is vigorous at first and cooling is necessary. The mixture is refluxed for one hour on a steam bath, then cooled and poured into a mixture of 500 g. of cracked ice and
200 g. of concentrated hydrochloric acid. The
benzene layer is separated, and the aqueous layer is extracted once with a mixture of
100 cc. of benzene and
100 cc. of ether (Note
2). The
ether-
benzene solution is washed once with 100 cc. of water (Note
3), and then dried over
40–50 g. of calcium chloride. The solution is filtered (Note
4) with suction into a
1-l. Claisen flask, and the solvent is removed by distillation under reduced pressure (Note
5); the residue consists of a brown oil which solidifies on cooling.
The crude material (
91–92 g.) is purified by distillation under reduced pressure from a
250-cc. Claisen flask (Note
6). The product distils at
160°/5 mm. (
172°/15 mm.;
200°/30 mm.) as a colorless oil which solidifies on cooling. The yield is
81–82 g. (
82–83 per cent of the theoretical amount based on the
phenylacetic acid used) of a product which melts at
53–54°. The product is recrystallized from
methyl alcohol, using 4 cc. of solvent for each gram of product (Note
7); the yield is
55–56 g. of crystals melting at
55–56°. An additional
7 g. of crystals melting at
55–56° is obtained by cooling the filtrate in an
ice-salt bath. On further cooling of the mother liquors, about
5 g. of crystals melting at
54–55° is obtained. The total yield of purified product is
67–70 g. (Note
8). Further recrystallization of the product from
methyl alcohol does not raise the melting point above
55–56°.