Ionic imidazolium derivatives

The first use of room temperature ionic liquids as potential novel soluble phases for combinatorial synthesis has recently been described. As model reaction the Knoevenagel condensation of salicyl aldehyde grafted on to an imidazolium-derived ionic liquid was studied under the action of microwave irradiation (Scheme 12.19) [66]. Reactions were performed without additional solvent in the presence of a basic catalyst, utilizing microwave irradiation in a designated monomode microwave reac-... 

Minami I, Watanabe N, Nanao H et al (2008) Improvement in the tribological properties of imidazolium-derived ionic liquids by additive technology. J Synth Lubr 25 45-55... 

Catalytic hydration of phenylacetylene has been accomplished in a biphasic mixture of ionic liquids and toluene using [BMTz] [AuCl3Br] 15 as a catalyst (Scheme 6) [114], Several imidazolium derived ionic liquids, as weU as 15, can be... 

Scheme 7 Synthesis of gold-carbene complexes 16 from imidazolium derived ionic liquid 15...

The use of various low-water reaction systems, including anhydrous organic solvents as well as imidazolium-based ionic liquids, is investigated for the biocatalytic preparation of lipophilic derivatives of various natural phenohc compounds (Figure 9.1) including phenohc and flavonoid glycosides (escuhn, salicin, helicin. 

Strategy C, solvent-less conditions. An example of catalyst design by tailoring a task specific ionic liquid in such a way to fulfill all the mechanistic requests of the Baylis-Hillmann reaction is offered by imidazolium derivative 10 (Figure 9). 

Supported liquid acrylic esters have been prepared from hydroxylated imidazolium-based TSILs and used neat in (4-1-2) Diels-Alder cydoadditions. First, Handy et al. [31] used a fructose-derived ionic liquid to support acryUc acid and performed the Diels-Alder cycloaddition with several dienes induding cydopenta-and cydohexadienes and butadiene derivatives at 120 °C for 12 h in the presence of hydroquinone (Scheme 5.5-25). 

The real breakthrough in the use of ionic liquids as solvents came in 1992, when Wilkes and Zaworotko studied the formation of dialkylimidazolium salts associated with water-stable anions. This led to the discovery of the ionic liquids [emim][BF4] 5 (Figure 2.2) and [emim][N03], with melting points of 15°C and 38" C, respectively. These ionic liquids are hygroscopic, but they are not degraded in the presence of moisture. Shortly afterward, the synthesis of the corresponding hexafluorophosphate derivative 6 was described. Today, most ionic liquids are based on imidazolium derivatives associated with non-covalent anions. 

Unlike polarity, the solubility of ionic liquids depends strongly on the structure of the associated anion. In fact, the miscibiUty of ionic liquids with traditional solvents is one of their most interesting features and is clearly observed during the anion metathesis of imidazolium derivatives. The starting chlorine salt, for example [bmim][Cl], is completely soluble in water. After exchange of the anion, [bmim][PF6] or [bmim][NTf2] salts are obtained as hydrophobic products and therefore form a separate layer. Table 2.7 summarizes the solubility of l-butyl-3-methylimidazolium salts as function of the anion. ... 

Most tetrafluoroborate and hexafluorophosphate ionic liquids are patent free however, owing to their cost, their insufficient stability toward hydrolysis and issues concerning their disposal, such ionic liquids are not useful for industrial applications. These problems prompted researchers to develop new types of ionic liquids with different anions, many of them being protected by state-of-the-matter patents, for example, HSOJ (Ref. 184), PF3(C2F5)J (Ref 185) and borate derivatives. To solve the problem of the high cost of imidazolium-based ionic liquids, one patent claims broad coverage of cheap phosphonium ionic liquids. ... 

Imidazolium-based Ionic Liquids are of considerable interest for electrochemical applications. The hydrogen of the imidazolium group can be substituted easily and therefore a variety of properties are achievable. Probably the most widely used imidazolium-based ILs are the 1,3-aIkyl substituted derivatives, due to their low melting points, relatively low viscosity and high conductivities. Their physical and... 

In situ generation of Pd-NHC complexes in an imidazolium-type ionic liquid matrix and grafting of the catalyst on the surface of silica was reported by Karimi and Enders [41]. Pal-ladium(II) anchored on an ionic Uquid matrix, derived from A-3-(3-trimethoxysilylpropyl)-3-methyl imidazolium chloride, displays high thermal stabihty up to 280 °C. Catalyst 8... 

Aluminium is considered to be a very suitable material for the cathodic current collector in lithium-ion batteries, but it may corrode in contact with the electrolytes used in that kind of devices. The use of ionic liquids as corrosion inhibitors of aluminium and aluminium alloys was pointed out by Uerdingen et al. [6] when an Al- alloy (AlMg3) showed a very low corrosion rate (0.03 mm-year ) in the presence of different imidazolium derivatives with different and varying anions (ethylsulphate, octylsulphate, tosylate and dimethylphosphate), especially in the absence of water. Adding 10 % of water, mass loss values were under 0.1 mm-year. ... 

Ibrahim MAM, Messali M, Moussa Z, Alzahrani AY, Alamry SN, Hammouti B (2011) Corrosion inhibition of carbon steel by imidazolium and pyridinium cations ionic liquids in acidic environment. Port Electrochim Acta 29(6) 375-389. doi 10.4152/pea.201106375 Zarrouk A, Messali M, Zarrok H, Salghi R, Ali AA, Hammouti B, Al-Deyab SS, Bentiss F (2012) Synthesis, characterization and comparative study of new functionalized imidazolium-based ionic liquids derivatives towards corrosion of C38 steel in molar hydrochloric acid. Int J Electrochem Sci 7(8) 6998-7015... 

Ionic Liquids with different unsymmetrical cations. The most important classes are Ionic Liquids having as cation either imidazolium derivatives or quaternary ammonium ions pyrrolidimium-, piperidimium-, or morpholinium-based derivatives or quaternary phosphonium ions [23]. As counterions, simple halogenides are possible or more hydrophobic ions such as PFg or bis ((trifluoromethyl) sulfonyl) amide (N(S02CF3)2). ... 

For the purpose of developing ionic liquids which molecularly dissolve biopolymers, we designed ether-containing N, IV -dialkyl imidazolium derivatives 26,27 [120]. These compounds are obtained as solid after tfeeze drying. They eventually become liquid at room temperature in air, probably due to absorption of water from the atmosphere. These ionic liquids were miscible with water. The content of water in these ionic liquids was 2.6 wt% for 26 and 2.5 wt% for 27, as determined by Karl Fischer s method. To compare the solvent properties of these ionic liquids with conventional ionic liquids, compound 25 was saturated with water (water content, 2.5 wt%) and used as a reference. 

Freire, M., Neves, C., Marrucho, L, Coutinho, J., Fernandes, A. (2010). Hydrolysis of Tetrafluoroborate and Hexafluorophosphate Counter Ions in Imidazolium-Based Ionic Liquids. /, Phys. Chem., Vol. 114, No. 11, pp. 3744-3749, ISSN 1089-5647. Gordon, E., Cohen, J., Engel, R., Abbott, G.W. (2006). l,4-Diazabicyclo[2.2.2]octane Derivatives A Novel Qass of Voltage-Gated Potassium Channel Blockers. Mol. Pharmacol, Vol. 69, No. 3, pp. 718-726, ISSN 0026-895X. 

Nakajima H., Ohno H. (2005). Preparation of thermally stable polymer electrolytes from imidazolium-type ionic liquid derivatives. Polymer, vol. 46, n°25 pp.11499-11504, (December 2005), ISSN 0032-3861... 

Tuba, Z. and Kollar, L. (2003) Palladium-catalysed aminocarbonylation of steroidal 17-iodo derivatives in KAf-dialkyl-imidazolium-type ionic liquids. Green Chemistry, 5, 643-645. 

Gardas RL, Freire MG, Carvalho PJ, Marrucho IM, Fonseca IM, Ferreira AGM, Coutinho JAP (2007) High-pressure densities and derived thermodynamic properties of imidazolium-based ionic liquids. J Chem Eng Data 52 80-88... 

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