Organic synthesis ionic liquids, application

Apart from the extensive use of ILs in catalysis and organic/inorganic synthesis [11,12] (see also Chapter 5 and Section 6.1) their advantages for materials chemistry, and especially for the synthesis of novel nanostructures, have been only gradually realized in recent years. This contribution will actualize a recent review [13] and aims to introduce this specific field of ionic liquid applications which undoubtedly promises great potential for future research and development. 

However, ionic liquids containing other classes of organic cations are known. Room-temperature ionic liquids containing organic cations including quaternary ammonium, phosphonium, pyridinium, and - in particular - imidazolium salts are currently available in combination with a variety of anions (Figure 3.1-1 provides some common examples) and have been studied for applications in electrochemistry [7, 8] and in synthesis [9-11]. 

Chloroaluminate(III) ionic liquid systems are perhaps the best established and have been most extensively studied in the development of low-melting organic ionic liquids with particular emphasis on electrochemical and electrodeposition applications, transition metal coordination chemistry, and in applications as liquid Lewis acid catalysts in organic synthesis. Variable and tunable acidity, from basic through neutral to acidic, allows for some very subtle changes in transition metal coordination chemistry. The melting points of [EMIM]C1/A1C13 mixtures can be as low as -90 °C, and the upper liquid limit almost 300 °C [4, 6]. 

In comparison with traditional biphasic catalysis using water, fluorous phases, or polar organic solvents, transition metal catalysis in ionic liquids represents a new and advanced way to combine the specific advantages of homogeneous and heterogeneous catalysis. In many applications, the use of a defined transition metal complex immobilized on a ionic liquid support has already shown its unique potential. Many more successful examples - mainly in fine chemical synthesis - can be expected in the future as our loiowledge of ionic liquids and their interactions with transition metal complexes increases. 

This chapter will deal with applications of microwave irradiation in the synthesis of heterocycles by a variety of means, excluding cycloadditions, which will be described in the next chapter. We have chosen to report first reactions in solution in organic solvents, then heterogeneous reactions without solvent under a variety of conditions, and finally to deal with emerging techniques which employ ionic liquids. 

Room-temperature Ionic Liquids (RTIL) - Synthesis and Applications in Organic Synthesis under the Action of Microwaves... 

Ionic liquids (ILs) are, together with water and supercritical fluids, one of the few alternative media for environmentally friendly processes, which seem to have more possibility of industrial application in the next 10 years. The range of demonstrated or proposed applications of ILs is extraordinary, going from their use as nonvolatile, non-flammable solvents in organic synthesis to catalysts, materials for aiding separations and gas capture, advanced heat transfer fluids, lubricants, antistatics, and so on [2 ]. Surpassing in magnitude the number of potential uses is the number of possible IL compositions, estimated to be in the billions [5]. The term ionic liquids includes all compounds composed exclusively by ions that are liquid... 

Aminocarbonylation provides an efficient method for the synthesis of carboxamides from readily available alkenyl halides. This reaction finds many applications in organic synthesis, especially for the introduction of amides with a variety of A -substituents. For example, steroidal alkenyl iodide 137 was transformed to the corresponding amide derivative 138 in 88% yield through aminocarbonylation (Equation (10)). In this reaction, the palladium catalyst was recovered by using an ionic liquid, l-butyl-3-methylimidazolium salt 139, as reaction media, and reused five times with only a minor loss of activity. ... 

Lina Mehta obtained B.Sc., M.Sc., and Ph.D. degrees in India before moving to the Chemistry Department at Brunei University in 1989 as a postdoctoral research fellow. Her work has been centered mainly in synthetic organic chemistry associated with anticancer research in collaboration with Cancer Research UK, Gray Cancer Research Trust, and Royal Marsden Hospital in the UK, and with several other research institutes in the USA and Australia. The Chemistry Department at Brunei finally closed in 2000 and Dr. Mehta moved into the Centre for the Environment and subsequently into the Institute for the Environment at Brunei. Her main area of research at present is on the synthesis and application of ionic liquids to environmental problems. She has published numerous research papers in various journals and co-authored reviews on aspects of heterocyclic chemistry for several well-known series of books. 

Ionic liquids have become a focus of increasing interest over the last decade.1 Some of this interest is due to their possible use as greener alternatives to volatile organic solvents (see below). There is, however, also a great deal of fundamental interest in how the unusual solvent environment that they present might affect reactions conducted in them. Recently, there have been a number of excellent ionic liquid reviews concerning their chemical and physical properties,2 and applications in synthesis and catalysis.1,3,4 It is remarkable that in 1999 it was possible to... 

Ionic liquids have been a popular topic of interest in 2002 and a review of the applications of these solvents in organic synthesis has been published (02ACA75>. New, densely functionalized fluoroalkyl-substituted imidazolium ionic liquids have been reported <02TL9497>. An ultrasound-assisted preparation of a series of ambient-temperature ionic liquids, l-alkyl-3-methylimidazolium halides, which proceeds via efficient reactions of 1-methyl imidazole with alkyl halides/terminal dihalides under solvent-free conditions, has been described <02OL3161>. New hydrophilic poly(ethyleneglycol)-ionic liquids have been synthesized from... 

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