Ethyl chloroaluminate

The chloroaluminate(III) ionic liquids - [EMIM][C1-A1C13], for example (where EMIM is l-ethyl-3-methylimidazolium) - are liquid over a wide range of AICI3 concentrations [24]. The quantity of AICI3 present in the ionic liquid determines the physical and chemical properties of the liquid. When the mole fraction, X(A1C13), is below 0.5, the liquids are referred to as basic. When X(A1C13) is above 0.5, the liquids are referred to as acidic, and at an X(A1C13) of exactly 0.5 they are referred to as neutral. 

Recently, there has been considerable interest in developing molten salts that are less air and moisture sensitive. Melts such as l-methyl-3-butylimidazolium hexa-fluorophosphate [211], l-ethyl-3-methylimidazolium trifluoromethanesulfonate [212], and l-ethyl-3-methylimidazolium tetrafluoroborate [213] are reported to be hydro-phobic and stable under environmental conditions. In some cases, metal deposition from these electrolytes has been explored [214]. They possess a wide potential window and sufficient ionic conductivity to be considered for many electrochemical applications. Of course if one wishes to take advantage of their potential air stability, one loses the opportunity to work with the alkali and reactive metals. Further, since these ionic liquids are neutral and lack the adjustable Lewis acidity common to the chloroaluminates, the solubility of transition metal salts into these electrolytes may be limited. On a positive note, these electrolytes are significantly different from the chloroaluminates in that the supporting electrolyte is not intended to be electroactive. 

While this reaction to form coumarin derivatives can be completed in mineral acids, research shows that the reaction was much faster in ILs even at room temperature. The same group used l-butyl-3-methylimidazolium hexafluoro-phosphate IL at high temperatures without employing any acid catalyst. The yields were comparable to chloroaluminate ILs with catalytic amounts of acid at room temperature. They also concluded that Bronsted acidity (produced by HF when [bmimJIPF ] contacts water) was not responsible for the observed activity. Singh et al have used l-butyl-3-methylimidazolium hydrogen sulfate IL in combination with microwave irradiation. They were able to synthesize coumarins in quantitative yields with drastic reduction in reaction times. Soares et al have used [bmim][NbCl6] IL to perform the Pechmann reaction using various phenols with ethyl acetoacetate to produce coumarin in moderate yields (-35%). 

We tried a different approach to create a supported chloroaluminate IL on silica to be used for the toluene carbonylation reaction. A functionalized silica (2-(2-pyridyl)ethyl-functionalized silica gel (Sigma Aldrich 53,798-5) was reacted with one equivalent of n-propyl chloride in toluene (0.2 M) for 12 h at 140 °C to form the quaternary ammonium chloride." The pyridyl concentration on the silica was 1.3 mmol/g silica per the vendor. Prior to reaction with the -propyl chloride, the solid was evacuated at 150 °C for 1 h. The supernatant liquid was decanted, then the solid was evacuated at room temperature overnight. A small portion of this solid was examined by C-MAS-NMR to determine how well the quaternization reaction had occurred. The spectra of the sample before and after treatment with the -propyl chloride were compared to show the same peaks in both samples 1.42, 12.22, 29.87, 47.81, 110.5, 120.8, 134.9, 147.4, and 163.5 ppm however, the treated sample showed the peak at 110.5 ppm grew after the treatment confirming the success of the quaternization reaction. This... 

The electrochemical reduction of TiCU and ZrCl4, in chloroaluminate melts and other molten salt systems, to lower valent halides has been fairly widely studied [4-7]. This has also been extended to studies of centered hexanuclear Zr halide clusters. Thus, ambient temperature AICI3 -1 -ethyl-3-methylimidazolium chloride (ImCl) molten salts, both basic (40/60 mol% AlCls/ImCl) and acidic (60/40 mol% AICI3 /ImCl), were used in an electrochemical investigation of clusters... 

Formation of several successive layers of bulk intermetallic compounds has been shown. Also, Lee et al. [480] have detected, during Al UPD, the formation of two alloys on polycrystalline Au electrodes from acidic l-ethyl-3-methylimidazolium chloroaluminate that melt at room temperature. Moreover, in the Al UPD region, fast phase transition between these two intermetallic compounds has been evidenced. Later, the same group of researchers [481] has performed EQCM studies on Al deposition and alloy formation on Au(lll) in ambient temperature molten salts/benzene mixtures. 

Takahashi, S., Suzuya, K., Kohara, S., Koura, N., Curtiss, L.A., and Saboungi, M.-L., Structure of l-ethyl-3-methylimidazolium chloroaluminates Neutron diffraction measurements and ab initio calculations, Z. Phys. Chem., 209, 209-221, 1999. 

Smith, G.R, Dworkin, A.S., Ragni, R.M., Zingg, S.R, Bronsted superacidity of HCl in liquid chloroaluminate, A1C13—l-ethyl-3-methyl-lH-imidazolium chloride, J. Am. Chem. Soc., Ill, 525-529,1989. 

De Andrade, J., Does, E. S., and Stassen, H., A force field for liquid state simulations on room temperature molten salts l-ethyl-3methylimidazolium tetra-chloroaluminate, /. Phys. Ghent. B, 106, 3546-3548,2002. 

Abdulsada, A. K. et al., A fast-atom-bombardment mass-spectrometric study of room-temperature l-ethyl-3-methylimidazolium chloroaluminate(Iii) ionic liquids Evidence for the existence of the decachlorotrialuminate(Iii) anion. Org. Mass Spec., 28, 759, 1993. 

The electrodeposition of silver from chloroaluminate ionic liquids has been studied by several authors [45-47], Katayama et al. [48] reported that the room-temperature ionic liquid l-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF4) is applicable as an alternative electroplating bath for silver. The ionic liquid [EMIM]BF4 is superior to the chloroaluminate systems since the electrodeposition of silver can be performed without contamination of aluminum. Electrodeposition of silver in the ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) and l-butyl-3-methylimidazoliumhexafluorophosphate was also reported [49], Recently we showed that isolated silver nanoparticles can be deposited on the surface of the ionic liquid Tbutyl-3-methylimidazolium trifluoromethylsulfonate ([BMIMJTfO) by electrochemical reduction with free electrons from low-temperature plasma [50] (see Chapter 10). This unusual reaction represents a novel electrochemical process, leading to the reproducible growth of nanoscale materials. In our experience silver is quite easy to deposit in many air- and water-stable ionic liquids. 

The last electrolyte system to be mentioned in connection with lithium electrodes is the room temperature chloroaluminate molten salt. (AlCl3 LiCl l-/ -3/ "-imidazolium chloride. R and R" are alkyl groups, usually methyl and ethyl, respectively.) These ionic liquids were examined by Carlin et al. [227-229] as electrolyte systems for Li batteries. They studied the reversibility of Li deposition-dissolution processes. It appears that lithium electrodes may be stable in these systems, depending on their acidity [227], It is suggested that Li stability in these systems relates to passivation phenomena. However, the surface chemistry of lithium in these systems has not yet been studied. 

The ionic liquid emimcl-AlCls is l-ethyl-3-methylimidazohum chloroaluminate, see Yeung, K.-S. ... 

The same acidic chloroaluminate ionic liquids have been used as solvent for tungsten aryl oxide complexes for the metathesis of alkenes [24]. Slightly acidic chloroaluminates also dissolve the [Cl2W=NPh(PMe3)3] complex which catalyze ethene oligomerization without the addition of co-catalysts [25]. In a similar way, Ni-catalyzed 1-butene dimerization into linear octenes was carried out in acidic chloroaluminates buffered with small amount of weak bases [26]. Neutral chloroaluminates (l-ethyl-3-methylimidazolium chloride/AlCl3 = 1) were employed to immobilize ruthenium carbene complexes for biphasic ADMET (acyclic diene metathesis) polymerization of an acyclic diene ester [27]. 

Diels-Alder reactions." Addition of AICI3 to l-ethyl-3-methylimidazolium chloride forms a chloroaluminate ionic liquid. This substance accelerates and enhances the selectivity of Diels-Alder reactions. 

Sodium and lithium Both sodium [15] and lithium [16] electrodeposition was successful in neutral chloroaluminate ionic liquids that contained protons. These elements are interesting for Na- or Li-based secondary batteries, where the metals would serve directly as the anode material. The electrodeposition is not possible in basic or acidic chloroaluminates, only proton-rich NaQ or LiQ buffered neutral chloroaluminate liquids were feasible. The protons enlarged the electrochemical window towards the cathodic regime so that the alkali metal electrodeposition became possible. For Na the proton source was dissolved HQ that was introduced via the gas phase or via 1-ethyl-3-methylimidazolium hydrogen dichloride. Triethanolamine hydrogen dichloride was employed as the proton source for Li electrodeposition. For both alkali metals, reversible deposition and stripping were reported on tungsten and stainless steel substrates, respectively. 

Callium Elemental gallium can be electrodeposited from both chloroaluminate [17] and chlorogallate [18] ionic liquids. In the latter case l-ethyl-3-methylimidazohum chloride was mixed with GaQs, thus giving a highly corrosive ionic liquid that was studied for GaAs thin film electrodeposition. In the chloroaluminates Ga can be deposited from Lewis acidic systems. It was found that the electroreduction from... 

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