L-Butyl-3-methylimidazolium-based ionic liquids

Qi, S., Cui, S., Chen, X., and Hu, Z., Rapid and sensitive determination of anthraquinones in Chinese herb using l-butyl-3-methylimidazolium-based ionic liquid with P-cyclodextrin as modifier in capillary zone electrophoresis, /. Chromatogr. A, 1059,191-198, 2004. 

Other l-Butyl-3-methylimidazolium-Based Ionic Liquids... 

Fortunate G, Mancini PME, Bravo V, Adam C (2010) New solvent designed on the basis of the molecular-microscopic properties ob binary mixtures of the type protic molecular solvent + l-butyl-3-methylimidazolium-based ionic liquids. J Phys Chem B 114 11804-11819... 

Yu X, Dai J, Yang L, Xiao D (2010) l-Butyl-3-methylimidazolium based ionic liquid as solvent for determination of hydrophobic naphthol with the electrogenerated chemiluminescence of tris(2,2 -bipyridine) mthenium(ll). Analyst 135(3) 630-635. doi 10.1039/b916435a... 

Romero, C., Moore, H.J., Lee, T.R. and Baldelli, S., Orientation of l-butyl-3-methylimidazolium based ionic liquids at a hydrophobic quartz interface using sum frequency generation spectroscopy, J. Phys. Chem. C 111, 240-247 (2007). 

Fortunate, G., Mancini, P.M.E., Bravo, V., Adam, C. (2010). New solvent designed on the basis of molecular microscopic properties of binary mixtures of the type protic molecular solvent + l-butyl-3-methylimidazolium-based ionic liquids. The Journal of Physical Chemistry B, 114,11804-11817, ISSN 1520-5707 Hitchcock, P.B., Mohammed, T.J., Seddon K.R., Zora, J.A., Hussey, C.L., Ward, E.H. (1986). 

Vakili-Nezhaad G, Vatani M, Asghari M, Ashour I (2012) Effect of temperature on the physical properties of l-butyl-3-methylimidazolium based ionic liquids with thiocyanate and tetrafluoroborate anions, and l-hexyl-3-methylimidazolium with tetralluoroborate and hexafluorophosphate. J Chem Thermodyn 54 148-154... 

Based on the properties of ionic hquids in high-temperature microwave-enhanced reactions, the authors chose l-butyl-3-methylimidazolium tetraflu-orophosphate ([bmimjPFe) as the suitable ionic liquid (Scheme 23). The addition of 0.15 mmol of [bmimjPFe to a reaction in 2.0 mL of DCF was found to increase the reaction rate dramatically and a set-temperature of 190 °C was reached in a mere 1 min, while the reactions programmed at 190 °C, in the absence of the ionic liquid, reached only 170 °C in 10 min. The reactions were finished in a mere 18-25 min of irradiation time, including the hydrolysis of the sensitive imidoyl chloride moiety with water. The formed bis-lactams were isolated in good yield and purity. 

Even though Ti02-based materials have been far more investigated than any other photocatalyst and this chapter is dedicated to these systems, it is important at least to mention here some of the promising alternative materials studied for wastewater treatment. CdS hollow nanospheres were prepared in a single-step hydrothermal route by Li et al. [109] using the ionic liquid l-butyl-3-methylimidazolium... 

Ionic liquids, having per definition a melting point below 100 °C, and especially room temperature ionic liquids (RTIL) have attracted much interest in recent years as novel solvents for reactions and electrochemical processes [164], Some of these liquids are considered to be green solvents [165]. The scope of ionic liquids based on various combinations of cations and anions has dramatically increased, and continuously new salts [166-168] and solvent mixtures [169] are discovered. The most commonly used liquids are based on imidazolium cations like l-butyl-3-methylimidazolium [bmim] with an appropriate counter anion like hexafluorophos-phate [PFg]. Salts with the latter anion are moisture stable and are sometimes called third generation ionic liquids. 

The use of two-phase catalysis in water or high-polar organic solvents is one of best approaches to clean catalytic hydrogenation (Hermann and Kohlpainter, 1993). Ionic solvents with a wide range of liquid phase (down to -81°C) based on l- -butyl-3-methylimidazolium cations can be used in these reactions. 

Liu Y, Wang M, Li J et al (2005) Highly active horseradish peroxidase immobilized in l-butyl-3-methylimidazolium tetrafluoroborate room-temperature ionic liquid based sol-gel host materials. Chem Commun 1778-1780... 

Certain quaternary salts of imidazoles have become important as ionic liquids, in particular salts of l-butyl-3-methylimidazolium (bmim). Preparation of imidazolium-containing ionic liquids, in the desired product ionic liquid as a solvent, is a virtually solvent-free, one-pot process proceeding in good to excellent yields <2003S2626>. There are also microwave-assisted, solvent-free processes for the preparation of imidazolium-based ionic liquids <2001CC643, 2003GC181>. 

The ionic liquid based on the l- -butyl-3-methylimidazolium cation was also used as an efficient catalytic medium for the chemoselective dithioacetalization of carbonyl compounds. This reaction proceeded with both activated and weakly activated aromatic aldehydes in almost quantitative yields in short reaction times. In addition, an acid-sensitive substrate such as furfural also gave the corresponding 1,3-dithiolane without a formation of any side products (Table 8). Moreover, aromatic ketones did not produce dithioketals under the same reaction conditions (room temperature, 10-20 min) or even after a prolonged reaction time <2004ASC579>. 

The use of ionic liquids in combination with CO2 has the potential to produce cleaner processes with improved selectivity. The negligible miscibility of the ionic liquid in CO2 compared with appreciable amounts of CO2 that can be found in the liquid phase make the use of CO2 as a green solvent attractive for continuous reaction processes. Sellin, Webb, and Cole-Hamilton conducted a hydroformylation of hex-l-ene and 1-octene catalyzed by rhodium based catalyst in l-butyl-3-methylimidazolium hexafluoro-phosphate (BMIMHF) in contact with CO2. Improved n iso product selectivity was obtained, compared with that using toluene with similar selectivity, but substantially lower yield (40% compared to >99%). Using 1-octene as a substrate and [Rh2(OAc)4]/[1-propyl-3-methylimidazolium] [PhP(C6H4S03)2] as catalyst, over 20 hr of continuous operation was achieved with minimal catalyst leaching at 373 K. 

Zhou G-P, hang Y, Huang X-R et al (2008) Catalytic activities of fungal oxidases in hydrophobic ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate based microe-mulsion. Colloids Surf B Biointerfaces 66 146-149... 

An ionic liquid (IL) is literally an ionic compound (a salt) that is a liquid. Of most current interest are salts that are liquids at room temperature (RTILs), or at least below 100 °C. There is a range of compounds that form room temperature ionic liquids dating back to ethanolammonium nitrate, (EtNH3)+(N03) (m.p. 14 °C), synthesised by Walden in 1914. Perhaps the most popular and well-studied are those based on the l-butyl-3-methylimidazolium (bmim) cation, such as brnim PFg (13.20) and bmim+BF4 which melts at ca. -80 °C. The imidazolium ionic liquids were initially used as their halogenoaluminate salts but they have a major drawback in that they are highly moisture sensitive. 

Based on their work on supercritical CO2 (see also Scheme 23), Reetz and Leitner introduced a technologically new and interesting continuous flow process for enzymatic reactions [65]. The group designed a protocol for enzymatic reactions, namely the lipase-catalyzed acylation (CAL B) of octan-1 -ol by vinyl acetate in ionic liquids (l-butyl-3-methylimidazolium bis(trifluo-romethanesulfonimide) [BMIM] [BTA]) using supercritical CO2 as the mobile phase (Scheme 25). The alcohol is pumped through the biphasic system and the products are obtained in solvent-free form in a cold trap. The enzyme/ionic liquid mixture can be recycled in batchwise or continuous flow operations. 

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