Ionic liquids recycling

These reactions occur with similar rates to those carried out in dipolar aprotic solvents such as DMF or DMSO. An advantage of using the room-temperature ionic liquid for this reaction is that the lower reaction temperatures result in higher selec-tivities for substitution on the oxygen or nitrogen atoms. The by-product (sodium or potassium halide) of the reaction can be extracted with water and the ionic liquid recycled. 

Metal Nanoparticles in Ionic Liquids Recyclable Multiphase Catalyst-Systems 13... 

Screening of the reaction media showed that, with the use of an ionic liquid/ water mixture (a so-called wet ionic liquid ), recycling of the catalyst could be improved compared to the reaction in ionic liquid without co-solvent. The com-... 

After performing the bioconversion in an ionic liquid, the product needs to be recovered and the biocatalyst and the ionic liquid recycled. Relatively volatile products can be removed by evaporation. Alternatively, immiscible organic solvents can be used to extract the product, and the biocatalyst can be recycled as a suspension in the ionic liquid phase [58]. A more elegant, green method, which avoids the use of volatile organic solvents altogether, involves the use of supercritical carbon dioxide as the extractive phase [96, 147, 148]. 

Considerations of ionic liquid recyclability, cost, toxicity etc. are also important. These are less pertinent for small-scale laboratory investigations but will become increasingly important as the field progresses towards larger scale synthesis for device applications. 

Frater T, Gubicza L, SzoUosy A, Bakos J (2006) Enantioselective hydrogenation in ionic liquids recyclability of the [Rh(COD)(DIPAMP)]BF4 catalyst in [bmim][BFJ. Inorg Chim Acta 359 2756-2759... 

He X, Chan TH (2006) New non-volatile and odorless organosulfur compounds anchored on ionic liquids. Recyclable reagents for Swem oxidation. Tetrahedron 62 3389-3394... 

D. W., Seddon, K. R., Thompson, J. M., and Wahala, K. 2005. Chloroindate(lll) ionic liquids recyclable media for Friedel-Crafts acylation reactions. Chem. Common. 903-905. 

In addition, Sodeoka and Kim described the successful reuse of BINAP-Pd complexes for reactions in ionic liquids. Recycled catalysts were reported to catalyze up to ten cycles without loss of ee [33, 34]. 

A first very important and far from trivial point is ionic liquid stability under the conditions required for the catalytic application under investigation. This point becomes especially interesting given the fact that in far the most cases the process development will aim for an extensive ionic liquid recycling, which naturally implies special requests for long term stability issues. 

Dupont J, Fonseca GS, LFmpierra AP, Fichtner PFP, Texeira SB (2002) Transition-metal nanoparticles in imidazolium ionic liquids recyclable catalysts for biphasic hydrogenation reactions. J Am Chem Soc 124 4228 229... 

Fig. 5. Result of the ionic liquid recycle test. Reaction conditions anhydride urea AGU molar ratio 3 3 1, reaction time 3 h, reaction temperature I207C [From Xie Shao, 2009]...

The author likes to thank the many researchers who responded to his request about their experience with ionic liquids recycling and reuse. Very deep thanks shoidd go to Dr. G. W. Meindersma (Eindhoven University of Technology, The Netherland) for the invaluable... 

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