Urea → 4-Fluorobenzamide

Participants

Reaction Conditions

Reaction Steps

70.0 g (0.5 mol) of 4-fluorobenzoic acid, 30.0 g (0.50 mol) of urea and 0.5 g of phosphorous acid are heated in 100 ml of mesitylene with stirring at from 150 to 158° C. for 8 h. After cooling to 25° C. the solid is filtered off with suction and is washed with 50 ml of mesitylene. The filter cake is introduced into 250 ml of water, and the mixture is adjusted to a pH of 12 with aqueous sodium hydroxide solution and subjected to steam distillation. Subsequently the solid is filtered off with suction and dried at 100° C. 50.7 g of 4-fluorobenzamide are obtained having a melting point of from 147° to 150° C. This corresponds to a yield of 72.9% of theory. By acidification of the aqueous mother liquor to a pH of 2, 5.9 g of 4-fluorobenzoic acid (8.4% of theory) are obtained, which can be employed again in a subsequent batch.

Provenance & Evidence