Phosphonic acid → Azacyclopentane-2,2-diphosphonic acid

Participants

Reaction Steps

85.0 gm of 2-pyrrolidone (1.0 mol) and 164 gm of H3PO3 (2.0 mols) were melted at 80°C. While stirring this melt, 176 ml of PCl3 (2.0 mols) were added thereto. The mixture was stirred for three additional hours and was left standing at 70°C overnight. Then, three liters of H2O were used for the hydrolysis. The solution was boiled with activated carbon; and after filtration, the reaction product was precipitated with acetone. The white substance was dissolved in water, and passed over a cation exchanger. The solution was concentrated; and the substance was separated upon the addition of ethanol. The yield of crystalline azacyclopentane-2,2-diphosphonic acid was 95 gm, or about 41% of the theory. The molecular weight of the compound was determined by titration to be 230 (calculated: 231.09).

Provenance & Evidence