Imidazolium tetrafluoroborate

As reported by Griengl and coworkers, benzaldehyde, decanal, undecanal, and dodecanal were reacted with HCN in a two-phase solvent system aqueous buffer and ionic liquids 1 -ethyl-3-methylimidazolium tetrafluoroborate, 1 -methyl-3-propylimidazolium tetrafluoroborate, and l-butyl-3-methyl-imidazolium tetrafluoroborate in the presence of the HNLs from Prunus amygdalus and Hevea brasiliensis. When compared with the use of organic solvents as the nonaqueous phase, the reaction rate was significantly increased and the enantioselectivity remained good [51]. 

Scheme 4.2 The preparation of imidazolium tetrafluoroborate ionic liquids (where R is an alkyl group)...

According to the nature of their counter anion, ionic liquids (ILs) can dissolve a large amount of carbohydrates. In 2003, Moreau and co-workers reported the acid-catalyzed dehydration of fructose in a microbatch reactor at 80°C using l-butyl-3-methyl imidazolium tetrafluoroborate (BM1M BF4 ) (hydrophilic), and l-butyl-3-methyl imidazolium hexafluorophosphate (BMIM Fe (hydrophobic) (Scheme 10) [95]. 

Similar good results of the separation of aromatic and aliphatic hydrocarbons were recently obtained with ethyl(2-hydroxyethyl)dimethylammonium Ws(trifluoromethylsulfonyl)imide, [(Cj)2C2HOC2N][Tf2N], at 298.15 K [160]. The separation of m-xylene from n-octane by extraction with [(Ci)2C2HOC2N] [TfjN] was observed with the distribution ration of 0.3 and selectivities of range 22-31. The other ammonium salt as [(Ci)2C4HOC2N][Bp4] or 1,3-dihexyl-oxymethyl-imidazolium tetrafluoroborate was not so successful in this separation [161]. 

Heintz, A. et al.. Excess molar volumes and liquid-liquid equilibria of the ionic liquid l-methyl-3-octyl-imidazolium tetrafluoroborate mixed with butan-l-ol and pentan-l-ol, /. Solution Chem., 34,1135, 2005. 

Kaliszan, R., Marszatt, M. R, Markuszewski, M. J., B czek, T., and Pernak, J., Suppression of deleterious effects of free silanols in liquid chromatography by imidazolium tetrafluoroborate ionic liquids, J. Chromatogr. A, 1030, 263-271, 2004. 

Husson-Borg, P, Majer, V., and Gomes, M. F. G., Solubilities of oxygen and carbon dioxide in butyl methyl imidazolium tetrafluoroborate as a function of temperature and at pressures close to atmospheric pressure, /. Chem. Eng. Data, 48, 480, 2003. 

Katsyuba, S. A., Dyson, P. J., Vandyukova, E. E., Chernova, A. V., and Vidis, A., Molecular structure, vibrational spectra, and hydrogen bonding of the ionic liquid l-ethyl-3-methyl-lH-imidazolium tetrafluoroborate, Helv. Chim. Acta, 87, 2556-2565, 2004. 

Heimer, N. E., Del Sesto, R. E., and Carper, W. R., Evidence for spin diffusion in a H,H-NOESY study of imidazolium tetrafluoroborate ionic liquids, Magn. Reson. Chem., 42, 71-75,2004. 

BMIm]BF4 BMImCl [BMIm]PF6 CCS ecu [Choline] [Pro] 1 -butyl-3-methyl-imidazolium tetrafluoroborate 1 -butyl-3-methyl-imidazolium chloride 1 -butyl-3-methyl-imidazolium hexafluorophosphate CO2 capture and storage/sequestration CO2 capture and utilization (2-hydroxyethyl)-trimethyl-ammonium (iS )-2-pyrrolidine-carboxylic acid salt... 

Finally, two interesting systems with nonconventional solvents were reported. One uses the ionic liquid 1-butyl-3-imidazolium tetrafluoroborate ([BMIM][BF4]), giving results quite similar to those in CH2C12 with a large excess of pyridine, with good conversion and selectivity for the diepoxide (entry 8) [61]. The other nonconventional solvent used is the fluorous solvent hexafluoro-isopropanol. In the presence of 2,2 -bipyridine, this system gives full conversion and selectivity at a very low catalyst loading of 0.1 mol% (entry 9) [62],... 

Low-yielding Diels-Adler reaction yields have been improved using ionic solvents salts as butyl-3-methyl-l-imidazolium tetrafluoroborate (3). 

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