On the acidity of substituted methylenediphosphonates and their interaction with alkali metal ions

Article abstract of DOI:10.1021/ic50057a013

The acidity of and Li⁺, Na⁺, K⁺, and Cs⁺ complexing with a series of substituted methylenediphosphonates have been determined at 25° in 0.5 M tetramethylammonium chloride. The acid properties of the alkyl-substituted methylenediphosphonates have been shown to be correlated with the electron-donor ability of the substituents attached to the bridging carbon atom. Also, logβ_MHiL (i = 0, 1) is predicted by an equation involving the reciprocal of the radius of the bare cation and the sum of the Taft σ* values. For 1-hydroxyethylidene-1,1-diphosphonic acid evidence is presented for intramolecular binding of the protons and the metal ions by the hydroxyl group.