Synthesis and Dissociation Constants of Calix(6) Arene Hydroxamic Acids

Abstract

Calix(6)arene hydroxamic acids (III) are synthesised for the first time by reacting calix(6)arene acid chloride(II) with substituted hydroxylamines at low temperature in the presence of sodium bicarbonate. The p-carboxycalix(6)arene(I) is obtained by an acid catalysed condensation reaction of p-hydroxybenzoic acid and formaldehyde. These calixarenes are characterised by melting point, UV, IR, 1H NMR and mass spectra. The thermodynamic ionization constants of calixarene hydroxamic acids have been determined by a pH titration technique in dioxane-water media.