Synthesis of Water-Soluble Calcium Complexes Based on (1-Hydroxyethylidene)diphosphonic, Nitrilotrimethylenephosphonic, Ethylenediaminetetraacetic Acids, and 2-Aminoethanol.

Water insoluble calcium hydroxide Ca(OH)2 or calcium carbonate CaCO3 react with aqueous solution of (1-hydroxyethylidene)diphosphonic acid and nitrilotrimethylenephosphonic acid to form poorly soluble calcium (1-hydroxyethylidene)diphosphonate trihydrate and calcium nitrilotrimethylenephosphonate trihydrate, respectively. The reaction of calcium chloride CaCl2 with the disodium salt of ethylenediaminetetraacetic acid afforded poorly soluble calcium ethylenediaminetetraacetate hexahydrate. The reaction of suspensions of complexes of (1-hydroxyethylidene)calcium diphosphonate trihydrate, calcium ethylenediaminetetetraacetate hexahydrate and calcium nitrilotrimethylenephosphonate trihydrate with 2-aminoethanol led to the formation of water-soluble (1-hydroxyethylidene)bis(2-aminoethanol)calcium diphosphonate, tris(2-aminoethanol)calcium nitrilotrimethylenephosphonate, and bis(2-aminoethanol)calcium ethylenediaminetetraacetate, respectively. The molecular structure of calcium ethylenediaminetetraacetate hexahydrate was characterized by single-crystal X-ray diffraction method. [ABSTRACT FROM AUTHOR]