Aluminum alloys--Bonding

Surface-modified alumina containing covalently-bonded p-aminophenyl groups was prepared by refluxing chromatographic grade alumina with p-aminophenylphosphonic acid in n-butanol. The resulting material, p-aminophenylalumina (PAPA), was evaluated for use as a stationary phase in high performance liquid chromatography (HPLC). When used with mobile phases consisting of acetonitrile and water, retention of solutes on the PAPA phase exhibited normal phase behavior, as evidenced by the increases in solute retention times with increasing percentages of acetonitrile. Excellent separations of carbohydrate mixtures were obtained on the PAPA stationary phase. Comparisons of the chromatographic properties the PAPA phase with those of commercial aminoalkyl silica stationary phases were also performed.

27Al nuclear magnetic resonance (NMR) has been employed to study the structure of aqueous aluminum nitrate solutions in the presence of phenylphosphonic acid, potassium dihydrogen phosphate and phosphoric acid. Evidence has been obtained which indicates that in aqueous solution, aluminum ions can be complexed with phosphonate or phosphate in either a 1:1 or 2:1 molar ratio, respectively. The relative percentages of these complexes in solution are shown to be dependent on the ratio of aluminum nitrate to phosphonate or phosphate as well as the degree of ionization of the phosphorus species.