Preparation of oxydicarboxylic acid salts

摘要

Oxyethylene dicarboxylic acid alkali metal salts are prepared from the corresponding oxydiethylene or polyoxyethylene diol and an aqueous alkali metal hydroxide in the presence of a catalytically effective amount of a nickel-copper-chromia catalyst at temperatures from about 200 to 300 DEG C. and pressures sufficient to maintain the reactants and products substantially in liquid phase. Preferably, the disodium salt of oxydiacetic acid is prepared by the oxidation of diethylene glycol with an aqueous sodium hydroxide solution in the presence of a catalytically effective amount of the nickel-copper-chromia catalyst. The disodium oxydiacetate can be readily precipitated from the crude reaction mixture by addition of a mixture of methoanol-isopropanol with subsequent filtration.