Water → Benzoylaminomethanephosphonic acid

Participants

Reaction Steps

561 g (5.5 mol) of acetic anhydride were cooled to 10° C. Then, a solution of 164 g (2.0 mol) of phosphorous acid and 300 ml of acetic acid were added dropwise in the course of one hour, with stirring and cooling. 302 g (2.0 mol) of N-hydroxymethylbenzamide were then added in portions in the course of 50 minutes at 10°-15° C., with cooling. Stirring was continued at 10° C. for 20 minutes. The reaction mixture was subsequently kept under reflux for 2.5 hours, followed by cooling. 61 g (3.39 mol) of water were then added dropwise at 25°-30° C., with cooling and stirring. After this, the mixture was refluxed again. After cooling, the mixture was stirred overnight and solids were then filtered off with suction. 320 g (approx. 75% of theory) of crude benzoylaminomethanephosphonic acid were obtained. Further crude acid could be obtained from the mother liquor.

Provenance & Evidence