Process and use of iminodisuccinic acid ammonium metal salts

摘要

Production of mixed ammonium-metal salts of iminodisuccinic acid involves mixing maleic anhydride with alkali hydroxide (optional) and water, adding ammonia to form the ammonium salt of iminodisuccinic acid and then reacting with metal oxide, hydroxide or other salt. A method for the production of iminodisuccinic acid ammonium/metal salts (I) involves: (a) mixing maleic anhydride (MA), alkali hydroxide and water in a mol ratio of 2:(0-3):(5-30) and then adding ammonia in the ratio (MA):(ammonia) = 2:(1.5-8) to form an iminodisuccinic acid ammonium salt of formula IDS(NH4)x(Na)y(K)z(H)m (II) and then (b) reacting compound (II) with metal oxide, metal hydroxide and/or other metal salts to form the mixed salt of formula IDS(NH4)x'(Na)y(K)z(M)m'.(NH3)n (III). IDS = iminodisuccinic acid residue; x = 0.1-4; x' = 0.1-3.9; y, z = 0-3; m = 0-2; m' = 0.1-2; n = 0-6; and M = Main Group II, III or IV metals, Sub-Group I-VIII metals, or lanthanides (in the oxidation state 1, 2, 3 or 4) Independent claims are also included for (1) ammonium salts (II) (2) ammonium salts of formula IDS(NH4)x''(H)y'' (IV) (3) ammonium/metal salts (III), except for the S,S-isomers of the calcium and magnesium ammonium/metal salts x'' = 2-4; and y'' = 0-2.