An acid-functionalized ionic liquid was entrapped within a silica gel to yield a recyclable liquid phase catalyst for the dehydration of rac-1-phenyl ethanol. Hot filtration tests showed that the activity was within the gel. Comparison with an analogous SILP system revealed fundamental differences in the properties and behavior of the materials.The discovery of facile ionic-liquid silica gel formation, 1,2 enabled the introduction of the first ionic liquid mediated sol-gel methods for the preparation of solid catalysts. [3][4][5] There followed a period of relatively few publications, during which ionic liquid gels were seldom investigated as catalysts. Currently, in parallel with the development of new classes of ionic liquid, and an increase in interest in softmatter, the area of ionic liquid gel catalysts has come back into focus, and new methods are emerging. This catalyst preparation methodology involves the entrapment of an ionic liquid within an inorganic oxide matrix by a gel method. At the same time a catalyst is co-entrapped, 3,[5][6][7] or, alternatively the catalytic center can be associated with the ionic liquid. 4 The worked-up material is then used as a heterogeneous catalyst. Materials consisting of an ionic liquid within a porous oxide are often referred to as ionogels. 8 These catalysts are a sub-set of the sol-gel prepared entrapped catalysts pioneered by Blum and Avnir. 9,10 In contrast to the gel-based catalysts, the related SILP catalysts, in which a heterogeneous catalyst is prepared by layering an ionic liquid on a pre-existing oxide matrix, have elicited an explosion of interest in the last ten years. Several reviews and concept articles have been published covering the method. [11][12][13][14][15][16][17] Exemplars have been demonstrated in the gaseous phase, 18 and using supercritical fluids, [19][20][21] and the application of SILP technology is at an advanced stage. The simplicity of the system enables a wide variety of matrices, ionic liquids and dopants to be screened easily. In liquid phase reactions the ease of addition and removal of the ionic liquid is potentially detrimental, and leaching can be facile.The development of supported nanoparticles catalysts by ionic-liquid assisted gel methods 3 has been recently developed further by Han and co-workers. 22 Catalysts with hierarchical pores were achievable by employing a metal salt (e.g. CaCl 2 ) initiated gelation. Doping with gold afforded a catalyst for esterification, and ruthenium catalyzed hydrogenation.The introduction of functionalized ionic liquids that are 'task specific' 23-26 opens up many new possibilities for the application of ionic liquids to liquid phase reactions, not least the incorporation of Brønsted-Lowry Acidic/Basic sites. Acid functionalized ionic liquids have been demonstrated as robust catalysts for continuous esterification in a miniplant. 27 In order to improve separation and prevent corrosion caused by liquid phase acids, it would be fortuitous to develop a heterogenised system. The combinat...

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