Patent ID: 7662990

Claim:
A process for the preparation of 3-(N-methyl-N-pentyl) amino-1-hydroxypropane-1,1-diphosphonic acid, monosodium salt, monohydrate of the formula I comprising: hydrolyzing N-methyl-N-pentyl-β-alanine methyl ester in water to produce an aqueous solution of N-methyl-N-pentyl-β-alanine of formula IV adding diethylcarbonate to the aqueous solution of the compound of formula IV; azeotropically removing the water to yield a diethylcarbonate solution of the compound of formula IV; bisphosphorylating the compound of formula IV by adding phosphoryl chloride and phosphorous acid to the diethylcarbonate solution of the compound of formula IV to yield 3-(N-methyl-N-pentyl) amino-1-hydroxypropane-1,1-diphosphonic acid; and forming the monosodium salt, monohydrate of 3-(N-methyl-N-pentyl) amino-1-hydroxypropane-1,1-diphosphonic acid.