Piperidinium-based ionic liquids (ILs) were synthesized under mild conditions by coordinating N -alkyl- N -methylpiperidinium bromide ([Pip 1,x ]Br) with anhydrous AlCl 3 . The weak basicity of N -methylpiperidine had little impact on downstream problems from proton impurities and catalyst poisoning. The results of Fourier transform infrared (FT-IR), electrospray ionization mass spectrometry (ESI-MS), and nuclear magnetic resonance ( 27 Al NMR) confirmed that the active components in [Pip 1,x ]Br-2AlCl 3 ( χ = 0.67) were [Al 3 Cl 9 Br] − and [Al 2 Cl 6 Br] − . Besides, the reaction performance of [Pip 1,8 ]Br-2AlCl 3 under different conditions was carried out by single-factor experiment and further confirmed by orthogonal experimental method. Among these reaction conditions, the optimal combination was the reaction temperature of 40°C, ILs/O molar ratio of 0.2:1, px/O molar ratio of 12:1, and the reaction time of 30 min. Furthermore, [Pip 1,8 ]Br-2AlCl 3 had excellent stability and can be recycled 14 times. It was the high-efficiency catalytic activity and prominent recyclability that made continuous industrial production possible.
A simple “one-pot” approach for the preparation of a new vinyl-functionalized organic–inorganic hybrid monolithic column is described. In this improved method, the hydrolyzed alkoxysilanes of tetramethoxysilane and triethoxyvinylsilane were used as precursors for the synthesis of a silica-based monolith, while 1-hexadecene and sodium ethylenesulfonate were used as vinyl functional monomers along with azobisisobutyronitrile as an initiator. The effects of reaction temperature, urea content, and composition of organic monomers on the column properties (e.g. morphology, mechanical stability, and chromatographic performance) were investigated. The monolithic column was used for the separation of neutral solutes by reversed-phase pressurized capillary. Furthermore, the monolith can separate various aromatic amines, which indicated its excellent cation-exchange capability and hydrophobic interactions. The baseline separation of the aromatic amines was obtained with a column efficiency of up to 78 000 plates/m.