Phosphonic acid → Azacyclopentane-2,2-diphosphonic acid
Reaction equation
[NH:1]1[CH2:5][CH2:4][CH2:3][C:2]1=O.[OH:7][PH:8]([OH:10])=[O:9].P(Cl)(Cl)Cl>O>[NH:1]1[CH2:5][CH2:4][CH2:3][C:2]1([P:8]([OH:10])(=[O:7])[OH:9])[P:8]([OH:10])(=[O:7])[OH:9]Participants
5
Reactant 3
Product 1
Reagents, catalysts & solvents 1
Procedure
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).