THE CHEMICAL-STABILITY, UNDER ALKALINE CONDITIONS, OF SUBSTITUTED IMIDAZOLINE RESINS AND THEIR MODEL COMPOUNDS

Imidazoline, a highly basic amine, was employed as a functional group in weak-base resins that were prepared for the extraction of gold cyanide from alkaline cyanide leach liquors. The chemical stability of the resins and their model compound analogues under these conditions was investigated. When the imidazoline group was attached to an acrylonitrile and a polystyrene matrix, it hydrolysed slowly to form an amide group. The attachment of lysidine (2-methylimidazoline) to a polystyrene matrix yielded a resin in which the hydrolysis product underwent a second hydrolysis to form an alkylamine group on the resin. The relative rates of hydrolysis of the resins were confirmed by an investigation using NMR spectroscopy of the hydrolysis reactions of the model compound analogues of the resins, i.e., lysidine (2-methylimidazoline), benzylimidazoline, and benzyllysidine (2-methylbenzylimidazoline). The hydrolysis products were the same as those for the resins; the rates of hydrolysis for the different structures increased in the order lysidine, benzylimidazoline, benzyllysidine. The model compounds are more rapidly hydrolysed than the resins-50% of the functional groups of the acrylonitrile-based imidazoline resin hydrolysed during four years of contact with an alkaline solution, whereas the model compound of this resin hydrolysed completely over a period of 320 hours. © 1990.