Preparation, of ionic liquids

This chapter will concentrate on the preparation of ionic liquids based on 1,3-dialkylimidazolium cations, as these have dominated the area over the last twenty... 

Ion exchange resin synthesis paths for the preparation of ionic liquids (adapted from... 

It is hoped that this section will give the reader a better appreciation of the range of ionic liquids that have already been prepared, as well as a summary of the main techniques involved and the potential pitfalls. While the basic chemistry involved is relatively straightforward, the preparation of ionic liquids of known purity may be less easily achieved, and it is hoped that the ideas given here may be of assistance to the reader. It should also be noted that many of the more widely used ionic liquids are now commercially available from a range of suppliers, including some specializing in the synthesis of ionic liquids [53]. 

Preparation of ionic liquids and their use [NR3R ][P(OPh- S03),(0Ph)y] Gelanese Ghemicals Europe, GmbH, Germany 2000 28... 

Preparation of ionic liquids for catalysis [BMIM][HS04], [HNR3][HS04] BP Ghemicals, UK Akzo Nobel NV, Netherlands Elemen-tis Specialities, UK 2000 30... 

Preparation of ionic liquids by treatment of amines with halide donors in the presence of metal halides [HNR3]C1/A1C13 Akzo Nobel NV, Netherlands 2000 31... 

Scheme 4.20 Preparation of ionic liquids under microwave conditions.

Tab. 8.5 Comparison of conventional and microwave heating for preparation of ionic liquids.

Deetlefs, M. Seddon, K. R. Improved preparations of ionic liquids using microwave irradiation. Green Chem., 2003, 5(2), 181-186. 

In 1997 Howarth [180] reported the preparation of ionic liquids 65 and 66. They reported that imidazolium cations can be used as Lewis acid centers in catalytic amount rather than as solvent (Scheme 66). The bromide salts 65a and 66 were prepared by a literature procedure [181] from TMS protected imidazole 64 and ethyl bromide or (5)-l-bromo-2-methylbutane in refluxing toluene in 46 and 21% yield, respectively. Salt 65a was converted into salt 65b with AgCF3COO in 89% yield. 

Protocol for the Deposition of Zinc from a Type III Ionic Liquid Preparation of Ionic Liquids... 

Salt synthesis is a helpful development for solving this problem. Acid esters are foremost among the salts used for this purpose. Tertiary amines are reacted with acid esters to introduce an alkyl group onto the nitrogen atom and prepare the onium cation. The reacted acid then remains as the counter anion. This method is well covered in several other books on ionic liquids [1]. Several acid esters are known to be effective for direct preparation. Recently even TFSI methyl ester was reported as an effective reagent for the preparation of ionic liquid containing TFSI... 

Ambient temperature molten salt can be obtained by several methods. One effective way to obtain a room-temperature molten salt is by the introduction of polyether chains to ions. The term polyether/salt hybrid is used in this chapter as a common name for polyether oligomers having anionic or cationic charge(s) on the chain (Figure 22.1). Polyethers, such as poly-(ethylene oxide) (PEO), are known as representative ion conductive polymers [1]. Polyether/salt hybrids have been studied as a kind of room-temperature molten salt apart from the development of onium-type ionic liquids [2]. The preparation of ionic liquids consisting of metal ions has been one of the important goals in this research field. Polyether/salt hybrid derivatives give one such solution for this task. 

Treatment of various 2-methylthiazolines with methyl iodide in nitromethane gave the corresponding AT-methylthi-azolinium salts in excellent yields <2004TL8899>. Treatment of thiazolines with various alkyl iodides (at reflux for 48 h) to form the corresponding ACalkylthiazolinium salts has been used in the preparation of ionic liquids <2003CC2914>. 

In an attempt to achieve solvent free preparation of ionic liquids, others have reported an improved approach whereby the reaction temperature was moderated by placement of the reaction vessel in a water bath. For example, Chan et al. [108] attempted to moderate the heat of the quatemisation reaction and thereby large scale preparation of imidazolium and pyridinium-based ionic liquids. Water moderation was successfully applied to avoid runaway reactions in the large-scale preparation of a number of ionic liquid precursors under solventless conditions using microwave irradiation ... 

Fig. 12.49 Preparation of ionic liquid phase-bound jS-oxo esters under microwave irradiations...

A scale-up preparation of ionic liquids is illustrative. Here the reaction of 1-methylimidazole with n-butyl bromide under solvent-free conditions is highly exothermic and prone to runaway in a batch reaction of any significant scale. However, using a flow reactor with reaction tubes between 2 mm and 6 mm diameter, fed by a micromixer with 0.45 mm channels, a continuous flow reaction at 85 °C was able to produce over... 

Amino acids, alcohols, acetic acid and acetic anhydride were pvirchased from Sigma-Aldrich. The preparation of ionic liquid [EtPy][CF3COO] was based on the literature method (14). 

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