Synthesis and Characterization of Bromoaluminate Ionic Liquids

Abstract

Twelve bromoaluminate based ionic liquids (ILs) were synthesized and characterized by IR, Raman, and NMR spectroscopy, as well as single crystal X-ray diffraction in part. Their principal physicochemical properties including melting points, conductivities, viscosities, and densities were determined and compared with related ILs. The influence of the cation and anion on the physicochemical properties are discussed. The [AlBr₄ ]^- based salts are-with one exception-solid at room temperature, while the compounds based on the anion [Al₂ Br₇ ]^- are liquid at room temperature. The liquid salts show low viscosities (49-139 mPa s), medium to high conductivities (0.76-3.53 mS cm^-1 ) and high densities (1.82-2.04 g cm^-3 ) at 28 °C. Furthermore, we showed aluminum electrodeposition from Lewis acidic ILs based on AlBr₃ and 1-hexyl-3-methylimidazolium bromide and investigated the stability range of various formulations.