氰基水解酯化

ETHYL PHENYLACETATE

[α-Toluic acid, ethyl ester]

Submitted by Roger Adams and A. F. Thal.

Checked by Oliver Kamm

1. Procedure

In a 3-l. round-bottomed flask, fitted with an efficient reflux condenser, are mixed 750 g. (918 cc.) of 95 per cent alcohol, 750 g. (408 cc.) of concentrated sulfuric acid and 450 g. (3.85 moles) of benzyl cyanide(Note 1). The mixture, which soon separates into two layers, is heated to boiling over a low flame, for six to seven hours, cooled, and poured into 2 l. of water, and the upper layer is separated. This is washed with a little 10 per cent sodium carbonate solution (Note 2) to remove small amounts of phenylacetic acid which may have been formed, and then distilled under reduced pressure. A small amount of water goes over first and then a pure product boiling 132–138°/32 mm. (120–125°/17–18 mm.) (Note 3). The yield is 525–550 g. (83–87 per cent of the theoretical amount).

2. Notes

1. The benzyl cyanide can be prepared according to the directions on p. 107; the product which boils over a 5° range should be used.

2. In washing the layer of ethyl phenylacetate with sodium carbonate it is sometimes advisable to add a certain amount of sodium chloride so that the ester will separate more readily.

3. The product obtained is water-clear and practically colorless. Although the product is collected over a 5° range, most of the liquid is found to boil over a 1° range, if distilled slowly without superheating. The boiling point of ethyl phenylacetate is near that of benzyl cyanide. However, a Kjeldahl analysis of the product shows that only a trace of nitrogen compounds is present.

3. Discussion

Ethyl phenylacetate can be prepared by the esterification of phenylacetic acid and alcohol by hydrochloric1 or sulfuric acid;2 and by the treatment of benzyl cyanide with alcohol and hydrogen chloride3 or sulfuric acid, which is much more convenient in the laboratory.

This preparation is referenced from:

z Org. Syn. Coll. Vol. 1, 107

z Org. Syn. Coll. Vol. 2, 288

References and Notes

1.Radziszewski, Ber. 2, 208 (1869).

2.Volhard, Ann. 296, 2 (footnote) (17); Senderens and Aboulenc, Compt. rend. 152, 1855

(1911).

3.Wislicenus, Ber. 20, 592 (1887); Ann. 296, 361 (17).Appendix

Chemical Abstracts Nomenclature (Collective Index Number);

(Registry Number)

hydrochloric

alcohol (-17-5)

sulfuric acid (76-93-9)

hydrogen chloride (77-01-0)

sodium chloride (77-14-5)

sodium carbonate (497-19-8)

Benzyl cyanide (140-29-4)

Phenylacetic acid (103-82-2)

α-Toluic acid, ethyl ester (93--0)

Ethyl phenylacetate (101-97-3)

Copyright © 1921-2005, Organic Syntheses, Inc. All Rights Reserved