Synthesis of functionalized phenylphosphinic acid resins through Michael reaction and their ion-exchange properties

Abstract

Novel, functional resins, containing variously substituted phenylphosphinic acid ligands, have been obtained via the Michael reaction. Reaction has been carried out on phenylphosphinic acid resin crosslinked with 2 wt.% of divinylbenzene using the following electrophiles: methyl chloroformate, ethyl bromoacetate, ethyl 2-bromopropionate, ethyl acrylate, ethyl methacrylate, acrylonitrile and methacrylonitrile giving the desired products with 60–97% yield. Resulting resins, having carboxylic acid function in α, β and γ position in respect to the phosphinic group have been used in ion-exchange/coordination of Cu(II), Cd(II), Ni(II), Zn(II) and Eu(III) from nitric acid solutions. It has been found that resins with carboxyl groups in α and β positions display higher divalent metal uptake, when the pH of the solution is above 1.5 and ion exchange is a prevailing process. Resins with either carboxyl or nitrile group in the γ position are less effective in metal ion uptake than the parent, phenylphosphinic polymer. In experiments with Eu(III) uptake from 0.1–1.0 M nitric acid solutions, where resins are supposed to operate mostly through coordination, none of synthesized resins performs better than the phenylphosphinic one. This means that introduction of carboxyl group to the phenylphosphinic acid ligand does not give a synergistic effect in coordination of metal ions.