Ionic liquids bulky organic cation

In contrast to most of the high energy-density alkali and silver (NO- and NO2-substituted) methanides, the ionic liquids of these methanides with a bulky organic cation are neither heat nor shock sensitive, and hence can be prepared and stored in large scale. Nevertheless, this type of methanide-based ionic liquids can also be considered energetic ionic liquids since the thermodynamically unstable methanide anion is only kinetically... 

Stabilized by bulky organic cations such as EMI+ or BMI+ [BMI+ = butyl(methyl) imidazolium]. Nitrosomethanide-based ionic liquids are very hygroscopic and immediately absorb water when exposed to air. The experimentally determined melting points vary between —4°C and 35 °C (Figure 40, Table 11), with the BMI+ salts always possessing the lower melting point. ... 

IC-MS has also been applied for the characterization of ionic liquids (IL) and for the investigation of their long-term stability under process-like conditions. The term ionic liquid commonly refers to a class of molten salts that are by definition liquid below 100 °C. They usually consist of bulky organic cations such as alkylated imidazole, pyrrole, or pyridine derivatives, or quatemized alkyl amines and alkyl phosphines. Common counterions are halides, alkyl sulfates, fluorinated hydrocarbons, carboxylic acids, or amino acids [268]. The physical and chemical properties of ILs are customizable by different cation-anion combinations and by the length of the alkyl chain of the cation. Depending on the... 

Ionic liquids are salts that form a stable fluid at or near room temperature and are expected to replace hazardous and volatile organic solvents because they have low vapor pressure, non flammability, high polarity and relative inertness. Most ionic liquids consist of bulky organic cations, for example Af,Af-dialkylimidazolium, A-alkylpyridinium, quaternary ammonium, quaternary phosphonium, and common weakly coordinating anions such as AlCU", Bp4 , PP6 , CFsSOs", TfO , (CP3S03)2N and some of them, such as Af,Af-dialkylimidazolium salts, show excellent conductivity [222]. Typical chemical structures of cations and anions are reported in Fig. 1.19. 

One more difference between ionic liqnids and conventional organic solvents of the C-Cl cleavage should be mentioned. Normally, the intrinsic solvation of the developing halide ion disfavors the cleavage via the entropy term. Such a term cannot be significant in the ionic liquids composed of very bulky cations and anions. 

The cations in ionic liquids are generally bulky monovalent organics. The typical cations of ionic liquids, not including the familiar alkylammonium and alkylphosphonium ions, are shown in Fig. 2. It is primarily the cations, which account for the low melting points of ionic liquids. The dialkylimidazolium ions, such as 1-butyl-3-methyl imidazolium [BMIM], have been widely investigated because low-melting ionic liquids can be made readily from such cations and because of their thermal and chemical stability. 

Danielsson et al. [25] have studied the synthesis of PEDOT in ionic liquids that utilize bulky organic anions, l-butyl-3-methylimidazolium diethylene glycol monomethyl ether sulfate and l-butyl-3-methylimidazolium octyl sulfate, the latter of which is a solid at room temperature and thus requires the addition of either monomer or solvent (in this case water) to form a liquid at room temperature. Polymerization in a water-free ionic liquid was only possible in the octyl sulfate species, but the polymerization of EDOT was successful in aqueous solutions of both the ionic liquids (0.1 M). The ionic liquid anions appear to be mobile within the polymer, exchangeable with chloride ions at a polymer/KCl(aq) interface, but it is interesting that when the PEDOT is in aqueous solutions of the ionic liquid, at higher concentrations (0.01-0.1 M) the imidazolium cation can suppress this anion response. The ion mobility in both the ionic liquid and in the polymer film in contact with the solution is significantly increased by addition of water. 

Separation science focuses on room temperature ionic liquids (RTlLs), salts that are liquid at ambient temperature. They have been studied as extracting solvents, stationary and mobile phases, mobile phase additives, and other uses. Common RTILs consist of a bulky nitrogen- or phosphorus-containing organic cation (pyridinium or pyrrolidinium, alkyl-imidazolium, ammonium or phosphonium) and a variety of organic and inorganic anions (triflate, dicyanamide, trifluoroacetate, acetate trifluo-romethylsulfate, nitrate, perchlorate, bromide, chloride, chloroaluminate, tetrafluo-roborate, hexafluorophosphate). 

Ionic liquids are salts that consist of cations and anions (51-56). Most commonly, the cations are bulky organic, symmetric, and asymmetric molecules (imidazolium. 

Among the many available ionic species, charged organic structures can afford numerous ion pairs because of their extensive diversity. For example, bulky geometries of both cation and anion constituents enable effective production of ionic liquids... 

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