Org. Synth. 1933, 13, 8
DOI: 10.15227/orgsyn.013.0008
[5(4)-Oxazolone, 2-phenyl-4-veratral-]
Submitted by Johannes S. Buck and Walter S. Ide.
Checked by John R. Johnson and H. R. Snyder.
1. Procedure
In a 2-l. Erlenmeyer flask, a mixture of 160 g. (0.96 mole) of veratraldehyde (Note 1), 192 g. (1.07 moles) of powdered, dry hippuric acid (p. 328), 80 g. (0.98 mole) of powdered, freshly fused sodium acetate, and 300 g. (278 cc., 2.9 moles) of high-grade acetic anhydride is heated on an electric hot plate, with constant shaking. The mixture becomes almost solid, and then, as the temperature rises, it gradually liquefies and turns deep yellow in color (Note 2). As soon as the material has liquefied completely the flask is transferred to a steam bath and heated for two hours. During this time a part of the product separates as deep yellow crystals. At the end of the heating 400 cc. of alcohol is added slowly to the contents of the flask. During this addition the flask is cooled slightly to moderate the vigor of the reaction. After allowing the reaction mixture to stand overnight, the yellow crystalline product is filtered with suction and washed on the filter with two 100-cc. portions of ice-cold alcohol and finally with two 100-cc. portions of boiling water. After drying, the product weighs 205–215 g. (69–73 per cent of the theoretical amount) and melts at 149–150°. This material is sufficiently pure for many purposes; it can be purified further by crystallization from hot benzene. In this way, using 1.2 l. of benzene, there is obtained 180–190 g. of the pure azlactone, melting at 151–152°.
2. Notes
1. The veratraldehyde obtained by methylating vanillin (p. 619) may be used without further purification.
2. The mixture should become completely liquid at a temperature of about 110°. Overheating should be avoided, since this causes the product to become red instead of bright yellow.
3. Discussion
The azlactones of α-benzoylaminocinnamic acids have always been prepared by the action of hippuric acid and acetic anhydride upon aromatic aldehydes,1 usually in the presence of sodium acetate.2 The procedure given here is essentially that of Kropp and Decker.3
This preparation is referenced from:

References and Notes
  1. Plöchl, Ber. 16, 2815 (1883).
  2. Erlenmeyer, Ann. 275, 3 (1893).
  3. Kropp and Decker, Ber. 42, 1184 (1909).

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)


5(4)-Oxazolone, 2-phenyl-4-veratral-

azlactones of α-benzoylaminocinnamic acids

alcohol (64-17-5)

Benzene (71-43-2)

acetic anhydride (108-24-7)

sodium acetate (127-09-3)

Hippuric acid (495-69-2)

Veratraldehyde (120-14-9)

vanillin (121-33-5)