Preparation of Iron(II) Water-Soluble Compounds Based on Iron(0), (1-Hydroxyethylidene)diphosphonic Acid, and Organic Amines.

The reaction of aqueous suspension of finely dispersed iron with one equivalent of (1-hydroxyethylidene) diphosphonic acid (H4L) results in poorly soluble iron(II) (1-hydroxyethylidene)diphosphate FeH2L·H2O. The reaction with two equivalents of the acid gives a water-soluble compound Fe(H3L)2, which undergoes disproportionation up to FeH2L·H2O and H4L. The reaction of a FeH2L·H2O aqueous suspension with an organic amine results in the dissolution of the complex. Heating the FeH2L·H2O aqueous suspension in a pressure reactor at 150°C in the presence of KF catalytic amounts causes the formation of a new crystal phase and X-ray-amorphous admixtures. [ABSTRACT FROM AUTHOR]