| abstract |
The process for the ethylenediaminetetraic acid (methylene phosphonic acid) of formula (A) or 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetra (methylene phosphonic acid) of formula (B) comprises the steps of: (a) dissolving aminophosphones acid in an aqueous solution of ammonium hydroxide, (b) adding a solution from the scannant in step (a) to the acid solution, (c) cooling the solution to a temperature ranging from 20 degC to 95 degC. C after the preceding steps, if this solution is heated, leaving the solution at a temperature of 1 to 24 hours to produce the acid aminophosphonate; acidic crystals of aminophosphones, and (e) washing the crystals with water. |