Sodium Hydroxide → [4-(2-Acetoxybenzoyl)-amino-1-hydroxybutylidene]-diphosphonic acid

Participants

Reaction Conditions

Reaction Steps

3.18 g (9.8 mmoles ) of sodium trihydrogen 4-amino-1-hydroxybutylidenediphosphonate trihydrate are added in 30 ml of water to 1.8 g (45 mmoles) of sodium hydroxide, 100 mg of p-dimethylaminopyridine and 200 mg of tetrahexylammonium iodide. The resulting solution is cooled to 0° C., and added with 2.03 g (10.2 mmoles) of 2-acetoxybenzoic acid chloride dissolved in 10 ml of diethyl ether. The reaction mixture is stirred for 2 hours at room temperature, then it is extracted with ethyl ether and the aqueous solution is acidified with concentrated HCl under stirring, with cooling. [4-(2-Hydroxybenzoyl)-amino-1-hydroxybutylidene]-diphosphonic acid precipitates, which is filtered, washed and dried at 70° C. and transformed into the title product by means of acetylation with acetic anhydride.

Provenance & Evidence