Exploiting the solvation properties of ionic liquids
A novel approach for the separation of zirconium from hafnium*
Hexamethylbenzene reacts differently with zirconiumand hafnium tetrachloride, affording, for the former, abinuclear molecular complex Zr(η6-Me6C6)Cl2(μ-Cl)3ZrCl3 and for the latter a binuclear ionic complex [Hf(η6-Me6C6)Cl3]+[Hf2Cl9]-. This difference in reactivity is exploited to carryout a two-phase extraction using 1-butyl-3-methylimidazoliumtetrachloroaluminate as the ionic liquid phase and a toluene/pentane mixture as the organic phase. This technique presentsthe potential advantage of recovering pure zirconium chloridewithout the formation of highly inert oxides.