Hippuric Acid → Azlactone

Participants

Reaction Conditions

Reaction Steps

This procedure is a modification of Crawford and Little (J. Chem. Soc. 1959, 729). A flask containing hippuric acid (20 g, 0.011 mol, Aldrich) and acetic anhydride (130 mL) was placed in a boiling H2O bath (90° C.) and vigorously stirred for exactly 15 min. The solution was poured onto 200 mL of toluene, 200 mL of ice water and stirred vigorously for 5 min. The phases were separated and the organic phase was stirred with 1 L of 2% aq. NaHCO3 for 10 min., separated and dried with anhydrous Na2SO4. Filtration of the solution and rotary evaporation (bath temperature 35° C., 20 mmHg) gave a yellow white solid. The formation of a red material in this procedure is due to protect degradation and condensation. Yield 11.8 g, 66%, mp 83°-86°. 1H NMR (CDCl3): δ7.95 (d, 2H; J=7 Hz); 7.55 (t, 1H, J=7 Hz), 7.45 (t, 2H, J=7 Hz), 4.38 (s, 1H). 13C NMR (CDCl3): 175.9, 163.4, 132.7, 128.8, 127.7, 125.8, 54.9.

Provenance & Evidence