Patent ID: 8487105

Claim:
A process for the preparation of a compound of Formula-1, wherein M is H + , Na + or K + and n is 1 or M is Mg +2 or Ca +2 and n is 2, comprising: a) reacting a compound of Formula-2, with a compound of Formula-3, in the presence of a base in a solvent to obtain a compound of Formula-4, then recrystallizing the compound of Formula-4 from a second solvent, thereby removing Impurity A and obtaining the compound of Formula-4 as a crystalline solid; b) reacting the recrystallized compound of Formula-4 with an acid in a solvent to obtain a compound of Formula-5, then recrystallizing the compound of Formula-5 from a hydrocarbon solvent, thereby removing Impurity B and obtaining the compound of Formula-5 as a crystalline solid; c) hydrolyzing the recrystallized compound of Formula-5 in the presence of a base in a solvent to obtain a carboxylic acid, then treating the carboxylic acid with an organic amine to obtain a compound of Formula 6, wherein R is alkyl, aryl, aralkyl or substituted aryl and R 1 is hydrogen, alkyl, aryl, aralkyl or substituted aryl, then recrystallizing the compound of Formula-6 from a second solvent; and d) treating the recrystallized compound of Formula-6 with a base in a solvent to obtain the compound of Formula-1.