Hippuric Acid → Azlactone

Participants

Reaction Conditions

Reaction Steps

101.6 g (0.567 mol) of hippuric acid was dispersed in 330 ml (3.49 mol) of acetic anhydride and heated to 80° C. in a water bath for about 20 minutes, thereby obtaining a solution of 2-phenyl-2-oxazolin-5-one. The thus obtained solution was cooled to -20° C. in a dry ice acetone bath. Thereto 93 g of anhydrous sodium acetate was added and the diaszonium salt solution prepared in advance was added to the mixture with vigorous stirring at a rate so as to maintain the reaction temperature at not higher than -10° C. After the completion of the dropping, the reaction mixture was held at -10° C. for 2 hours, and thereafter was stirred for 5 hours in an ice bath. Further, the mixture was stirred for one night in a water bath, and thereafter 1.5 l of water was added to filter out a yellow precipitate, which was washed with water to obtain the objective product.

Provenance & Evidence