Organic Syntheses, CV 1, 451
Submitted by Arthur Lapworth and Wilson Baker.
Checked by J. B. Conant and Mildred Evans.
1. Procedure
(
A)
Esterification of α-Cyano-β-phenylacrylic Acid.—In a
200-cc. round-bottomed flask fitted with a
reflux condenser,
50 g. (0.29 mole) of dry α-cyano-β-phenylacrylic acid (p. 181) is boiled for four and one-half hours with
100 cc. of absolute alcohol (p. 249) containing
3–4 g. of anhydrous hydrogen chloride (p. 293). The resulting solution is filtered rapidly while hot and allowed to stand overnight. Long, flat, colorless prisms separate which are filtered off with suction, washed with a little cold
alcohol, and dried in air. A further small quantity may be obtained by working up the mother liquor. The melting point of the
ethyl α-cyano-β-phenylacrylate is
50°, and the yield is
46.5–53 g. (
80–91 per cent of the theoretical amount) (Note
1).
(
B)
Addition of Sodium Cyanide to Ethyl α-Cyano-β-phenylacrylate.—
Twenty grams (0.1 mole) of cyanophenylacrylic ester is treated with
40 cc. of 50 per cent alcohol and
10 g. (0.2 mole) of finely powdered sodium cyanide. The mixture becomes warm and the
ester rapidly dissolves, the reaction being completed by heating on the
steam bath for two minutes. To this is added 200 cc. of water, and the resulting clear, colorless solution of the addition product is decomposed with
hydrochloric acid. This causes the precipitation of
ethyl α,β-dicyano-β-phenylpropionate as a yellowish oil, which on standing overnight and being stirred vigorously, or seeded if possible, sets to a yellowish solid mass. This is filtered off with suction and washed with cold water.
(
C)
Hydrolysis of Ethyl α,β-Dicyano-β-phenylpropionate.—The product thus obtained is hydrolyzed by boiling under a reflux condenser for four hours with
80 cc. of concentrated hydrochloric acid (sp. gr. 1.19). The substance goes into solution, and this clear solution, on cooling, deposits
phenylsuccinic acid in small crystals which are nearly colorless. These are filtered off, washed with cold water, and dried. The yield of product melting at
164–166° is
17.6–18.4 g. (
91–95 per cent of the theoretical amount based on the weight of
ester used) (Note
2) and (Note
3).
2. Notes
1. It is suggested that the esterification may be more conveniently carried out by substituting
95 per cent for absolute alcohol, and
25 g. concentrated sulfuric acid for the
hydrogen chloride, without affecting either the yield or quality of
ester (W. E. Barker, private communication).
2. The
phenylsuccinic acid, if slightly off color, may be recrystallized easily from a hot water solution by rapid cooling. Five grams is dissolved in 400 cc. of hot water, and then 60 cc. more of hot water is added. This solution is filtered and cooled in ice water with stirring until crystals separate. After standing, the crystals are filtered off. The yield is
4.5 g. (
90 per cent) of product melting at
167°.
3. The quantities of material used may be doubled from (
B) on, in which case the refluxing in (
C) requires at least one-half hour longer for complete solution. One run with double quantities yielded
32.6 g.
3. Discussion
This preparation is referenced from:
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