Abstract
Abstract The reaction of urea with 1-hydroxyethylidene diphosphonic acid in the ratios of 1 : 1, 1 : 2, 1 : 3 was first studied. As a result of the reactions, the corresponding 1 : 2 or 2 : 1 salts were formed, which can exhibit biological activity. The synthesized compounds were characterized by atomic emission spectroscopy, IR and NMR spectroscopy. According to atomic emission analysis, an increase in the amount of urea from 3 moles or more per 1 mole of 1-hydroxyethylidene diphosphonic acid does not cause an increase in the urea content in the final products. According to NMR spectroscopy data, compounds in the formation of which phosphoryl groups of 1-hydroxyethylidene diphosphonic acid are involved are in dynamic equilibrium salt–free acid.