Synthesis of functionalized phenylphosphinic acid resins through Michael reaction: Part II. Resins with multidentate ligands

Abstract

Functionalized resins, containing substituted phenylphosphinic acid ligands, were obtained by the reaction of styrene–divinylbenzene copolymer (2 wt.% of crosslinker, expanded gel structure) bearing phenylphosphinic acid groups with trimethylchlorosilane and then with an appropriate electrophile. Reactions were carried out with ethyl oxalylchloride, ethyl bromopyruvate and ethyl-4-chloroacetoacetate and resulted in resins with multidentate ligands, having acid capacities of 3.57, 3.86 and 3.33 mmol/g, respectively. These resins, obtained in 66–93% yield, were used in the removal of Cu(II), Cd(II), Ni(II), Zn(II), Mg(II) and Ca(II) from nitric acid solutions and their performance compared to the performance of the parent, phenylphosphinic acid resin. It was found that resin 1, obtained in the reaction of phenylphosphinic resin with ethyl oxalylchloride, has the highest affinity towards all of the above cations, whereas the remaining two resins performed similarly to the phenylphosphinic acid resin. New, functionalized resins were also used in an ester form for the removal of Au(III), Cu(II), Fe(III) and Ag(I) chlorocomplexes from hydrochloric acid solutions of various concentrations. It was found that resins in an ester form are able to selectively complex tetrachloroaurate from 0.5 to 6.0 M HCl. For example, ester form of resin 3 ( P=1.78, OH=0.64, %=70.30), removes the above mentioned chlorocomplexes from 1 M HCl solution. Log K d values are 4.08, 0.95, 0.97 and 1.46 for Au(III), Cu(II), Fe(III) and Ag(I), respectively.