Basic ionic liquid

Similar to the method of modifying neutral ionic liquids with strong Bronsted acids, a Lewis basie ionic liquid was also obtained by adding conventional base, such as NaOH, into the neutral ionie liquid. However, the solubility of the base in the ionie liquid is not high, and part of the [BMIM]PF6 was converted to a solid phase, probably beeause of the anion exehange between PF and OH 107,108). 

It has been noted that imidazolium ions are not inert. Under mild basic conditions, they are deprotonated to give reaetive nucleophiles. For reactions in basic media, the C2 hydrogen of the imidazolium ring can be replaced with an alkyl group. In one study, the C2 hydrogen was substituted by a methyl group. Ionie liquids based on the C2 methylated imidazolium cation were evaluated for the 

A weak base such as glycine added to [HMIMjPFg has also been reported to catalyze a Knoevenagel reaction of malononitrile and benzaldehyde 110). A KOH-treated [BMIMjPFg also provides a suitable medium for the Corey-Chaykovsky epoxidation of enones and cyclopropanation of aldehydes using trimethyl sulfonium iodide (///). 

F Impurity. It has been observed that [MIMjSbFg produced a small amount of fiuoride ion over time because of its sensitivity to air. Furthermore, residual chloride impurities have been found to exert a large influence on the physical properties of ionic liquids 115). 

Cl Impurity. Trace amounts of chloride impurities, which may be present at levels between 0.1 and 0.5mol/kg, have significant effects on the physical properties of ionic liquids, such as viscosity and density. Increases in viscosity are of particular concern in biphasic processes because of the formation of emulsions that affect the interface between the two phases 88). 

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Wilkes and co-workers have investigated the chlorination of benzene in both acidic and basic chloroaluminate(III) ionic liquids [66]. In the acidic ionic liquid [EMIM]C1/A1C13 (X(A1C13) > 0.5), the chlorination reaction initially gave chlorobenzene, which in turn reacted with a second molecule of chlorine to give dichlorobenzenes. In the basic ionic liquid, the reaction was more complex. In addition to the... 

A basic ionic liquid, l-methyl-3-butylimidazolium hydroxide ([bmIm]OH) and l-butyl-3-methyl-methylimidazolium tetrafluoroborate ([bmim]BF4), has been introduced as a catalyst and reaction medium for the Markovnikov addition of imidazoles 116 to vinyl esters 115 under mild conditions to give imidazoesters 117 <06JOC3991 06TL1555>. A series of (nitroimidazolyl)succinic esters and diacids were prepared from the Michael-type addition of the nitroimidazole to the a,P-unsaturated ester <06S3859>. 

Some ionic liquids have tunable Lewis acidities and basicities. The tuning can be achieved simply by varying the anion fraction in the overall ionic liquid composition. In some cases, Bronsted acidity can also be introduced into stable ionic liquids. Many publications show the broad applicability of acidic or basic ionic liquid media in catalysis replacing corrosive liquids and solid catalysts. 

The equilibrium (1) dominates in basic ionic liquids, where x AlCl3<0.5 the equilibrium (2) dominates in acidic ionic liquids, where x AICI3 >0.5. This means that over much of the liquid range the anions present in significant quantities are Cl, AICI4, and AI2CI7, and their relative amounts are controlled by the equilibrium ... 

The heptachloroaluminate ion is a strong Lewis acid, and chloride ion is the conjugate Lewis base. The basic ionic liquids, in which equilibrium (1) dominates, are light green in color, and the acidic ones, in which equilibrium (2) dominates, are darker and brownish in color (23). The acidic ionic liquids in this family are less viscous than the basic ones. 

The basic ionic liquid [BmimJOH has been introduced as a catalyst for the aza-Michael addition of aromatic amines and A-heterocycles to cyclic or acyclic ketones under solvent-free conditions.138... 

Yang Z-Z, Zhao Y-N, He L-N et al (2012) Highly efficient conversion of carbon dioxide catalyzed by polyethylene glycol-functionalized basic ionic liquids. Green Chem 14(2)519-527... 

Yang ZZ, He LN, Miao CX et al (2010) Lewis basic ionic liquids-catalyzed conversion of carbon dioxide to cyclic carbonates. Adv Synth Catal 352(13) 2233-2240... 

Yang Z-Z, He L-N, Dou X-Y et al (2010) Dimethyl carbonate synthesis catalyzed by DABCO-derived basic ionic liquids via transesterification of ethylene carbonate with methanol. Tetrahedron Lett 51(21) 2931-2934... 

The first electrodeposition of lithium from an ionic liquid was reported in 1985 by Lipsztajn and Osteryoung [2], They were able to deposit lithium from a 1-ethyl-3-methyl-imidazolium chloride/aluminum trichloride ionic liquid. They noticed that a neutral ionic liquid, a neutral basic ionic liquid (neutral + small excess of RC1) and a neutral acidic ionic liquid (neutral + small excess of AICI3) each have unique features. Both the basic and the neutral acidic ionic liquids show an extension of 1.5 V of the electrochemical window, making them interesting for electrochemical applications. 

The first example for biphasic oligomerisation of olefins in ionic liquids was published in 1990, reporting on the dimerisation of propene by nickel(II) catalysts in chloroaluminate ionic liquids of the general formula [cation]Clx-(AlCl3)y with either [C4Ciim]+, [C4py]+ or [(C4)4P]+ as cation.[10] It was found that in basic ionic liquids, y < 0.5, no catalysis took place. Excess chloride, which is present in such basic chloroaluminates, poisons the catalyst and it was shown that nickel compounds of the type NiCkCPRok... 

In the case of basic ionic liquids that contain AICI3 at less than 50 mol%, the metal salt acts as a Lewis acid by accepting the chloride anions in the ionic liquids to form a chlorocomplex anion ... 

The electrodeposition of indium. In, has been reported in a basic DMPICl—AICI3 ionic liquid [24]. Indium trichloride, InCl3, dissolves in the basic ionic liquid and forms a trivalent indium chlorocomplex anion, InClj, which can be reduced to metallic In by a three-electron transfer reaction ... 

The formal potentials of In(III)/In in the basic ionic liquids of 49.0 and 44.4 mol% AICI3 are reported as 1.009 and —1.096 V, respectively. A monovalent indium species, In(I), is not stable in this melt forming metallic In and InClj" as shown in the following disproportionation reaction ... 

The electrodeposition of tin, Sn, has been reported in both basic and acidic EMICI-AICI3 ionic liquid [26]. A divalent tin species, Sn(II), can be introduced by the anodic dissolution of metallic tin. The introduction of a tetravalent tin species, Sn(lV), is also possible by dissolving tin tetrachloride, SnCL,. However, the evaporation of SnCl4 occurs in the case of an acidic ionic liquid. The irreversible reduction of Sn(IV) to Sn(II) occurs at around 0.91 and —0.9 V in the acidic and basic ionic liquids, respectively. The electrodeposition of metallic Sn is possible by the reduction of Sn(II) ... 

The electrodeposition of antimony, Sb, has been reported in both acidic and basic BPCI-AICI3 ionic liquid [28, 29]. Antimony trichloride, SbCl3, is soluble in both acidic and basic ionic liquids. In the case of an acidic ionic liquid, a cationic trivalent antimony species, SbClJ, is formed and can be reduced to the metallic state ... 

The experimental value is reported as 0.389 V. On the other hand, an trivalent antimony chlorocomplex anions, SbCl4, is dominant in the basic ionic liquid and is also reducible to metallic Sb at more negative potential ... 

The electrodeposition of palladium, Pd, has been studied in a EMICI-AICI3 ionic liquid [61, 62]. Palladium dichloride, PdCl2, is soluble in the basic ionic liquid but less soluble in the neutral and acidic ionic liquids. In the basic ionic liquid, the divalent palladium species is considered to be PdCl, which is reducible to metallic Pd ... 

The electrodeposition of cadmium, Cd, is possible in the basic and neutral EMICI-AICI3 ionic liquids [56, 58]. In the basic ionic liquid, cadmium dichloride, CdCl2, dissolves and forms a divalent cadmium chlorocomplex anion, CdCl [69], which is reducible to metallic Cd at around — 1.2 V. In the case of a neutral buffered ionic liquid, the electrodeposition of Cd is observed at around —1.0 V, which is slightly positive than in the basic ionic liquid probably caused by the formation of more reducible species, CdCl3. ... 

The formal potentials of Hg /Hg and Hg /Hg are reported as 1.21 and 1.093 V, respectively. In case of the basic ionic liquid, HgCl2 dissolves and forms a divalent mercury chlorocomplex anion, HgCl . The reduction of HgCl results in the deposition of metallic Hg ... 

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