ROLE OF THE NATURE OF THE LIGAND IN INHIBITION OF METAL CORROSION BY PHOSPHONATES

Research on phosphonic acids and their complexes as inhibitors of meta l corrosion in near-neutral media has been reviewed. Their action, as a rule, cannot be attributed to adsorption on the metals, but may be u nderstood by taking into account reactions involving formation of comp lexes with different solubilities as well as the thermodynamic possibi lity of electrophilic (or less often, nucleophilic) substitution proce sses occurring. Possibilities are examined for making quantitative all owances and predictions of the role of the nature of the ligand in met al protection by phosphonates.