| abstract |
There is disclosed herein improved processes for the preparation of mixtures of alkali metal salts of 1-hydroxy-3-oxa-1,2,4,5-pentane tetracarboxylate and alkali metal salts of 3,6-dioxa-1,2,4,5,7,8-octane hexacarboxylate wherein D,L-tartaric acid is employed and recovered by lowering the pH of the reaction medium to within the range of from about 7 to about 9.5. At the reduced pH calcium D,L-tartrate precipitates and is easily separated. The recovered tartrate may be recycled to the synthesis reaction to prepare further product. |