Ionic liquids meetings

If ionic liquids meet certain precepts of green chemistr5f and sustainable development, they do not allow the development of nanoscale or solid materials at room... 

This table illustrates pretty well that the large-scale ionic liquid will probably not comprise a diallcylimidazolium cation and a [CE3S02)2N] anion. Over a medium-term timescale, we would expect a range of ionic liquids to become commercially available for 25-50 per liter on a ton scale. Halogen-free systems made from cheap anion sources are expected to meet this target first. 

Without a doubt, tetrafluoroborate and hexafluorophosphate ionic liquids have shortcomings for larger-scale technical application. The relatively high cost of their anions, their insufficient stability to hydrolysis for long-term application in contact with water (formation of corrosive and toxic HF during hydrolysis ), and problems related to their disposal have to be mentioned here. New families of ionic liquid that should meet industrial requirements in a much better way are therefore being developed. FFowever, these new systems will probably be protected by state of matter patents. 

Is there a "universal ionic liquid at the present state of development The answer is clearly no. Many of the ionic liquids commonly in use have very different physical and chemical properties (see Chapter 3) and it is absolutely impossible that one type of ionic liquid could be used for all synthetic applications described in Chapters 5-8. In view of the different possible roles of the ionic liquid in a given synthetic application (e.g., as catalyst, co-catalyst, or innocent solvent) this point is quite obvious. However, some properties, such as nonvolatility, are universal for all ionic liquids. So the answer becomes, if the property that you want is common to all ionic liquids, then any one will do. If not, you will require the ionic liquid that meets your needs. 

A new class of solvents called ionic liquids has been developed to meet this need. A typical ionic liquid has a relatively small anion, such as BF4, and a relatively large, organic cation, such as l-butyl-3-methylimidazolium (16). Because the cation has a large nonpolar region and is often asymmetrical, the compound does not crystallize easily and so is liquid at room temperature. However, the attractions between the ions reduces the vapor pressure to about the same as that of an ionic solid, thereby reducing air pollution. Because different cations and anions can be used, solvents can be designed for specific uses. For example, one formulation can dissolve the rubber in old tires so that it can be recycled. Other solvents can be used to extract radioactive waste from groundwater. 

S. J. Pool and K.H. Shaughnessy. Effects of ionic liquids on oxidative addition to square planar iridium and rhodium complexes. Abstracts of Papers, 231st ACS National Meeting, Atlanta, GA, USA, March 26-30,2006 (2006). 

Lob P, Lowe H, Hessel V, Hubbard SM, Menges G, Balon-Burger M (2006b) Determination of temperature profile within continuous micromixer-tube reactor used for the exothermic addition of dimethyl amine to acrylonitrile and an exothermic ionic liquid synthesis. In Proceedings of AIChE Spring National Meeting, Orlando, 23-27 April, 2006... 

Although the solubilities of gases in ILs are extremely important, at the time of this writing the number of published studies are limited. Some measurements were presented in oral and poster presentations at a five day symposium dedicated to ionic liquid research at the American Chemical Society national meeting in San Diego in April, 2001. Scovazzo et al. [14], for instance, presented preliminary results for CO2 and N2 solubility in [BMIM][PF6], and Rooney et aL [15] presented the solubihty of several gases in several different ILs as determined by the stoichiometric technique. A recent manuscript [16] presented Henry s law constants for H2 in two ILs. Given the lack of availability of other data, we concentrate below on the data collected in our laboratories. 

Campagna, S.R., Koronaios, R, Osteryoung, R.A., Cornman, C.R., Spectroscopy and coordination chemistry of iron(lll) tetraarylporphyrins in room-temperature ionic liquids. Book of Abstracts INOR-121, 217th ACS National Meeting, Anaheim, California, 1999. 

Fort, D. A., Swatloski, R. R, Moyna, R. et al.. Use of ionic liquids in the study of fruit ripening by high-resolution G NMR spectroscopy Green solvents meet green bananas, Chem. Commun., 714, 2006. 

The use of functionalised ionic liquids in catalysis is still very much in its infancy. The presence of a functional group may serve any of the following purposes in order to improve the catalytic reaction (i) assist in the activation of the catalyst (ii) generate a novel catalytic species (iii) improve the stability of the catalyst (iv) optimise immobilisation and recyclability (v) facilitate product isolation and (vi) influence the selectivity of the reaction. In addition, the functionalised ionic liquid has to meet certain requirements to be of use in synthesis/catalysis. Most important is their inertness with respect to the reaction in question. Also, the right balance between catalyst stabilisation and activation has to be found and this might require careful tuning of the reaction conditions. 

At the beginning of the century, the number of models capable of describing the molecular characteristics of ionic liquids was very limited and fragmented - only a few ionic liquids had been studied on an almost case-by-case basis [10-13], When Canongia Lopes and Padua developed and introduced their own force field [14] (nowadays, the CLAP force-field [14-17] is one of the most widely used force-fields for the molecular simulation of ionic liquids), their main goal was to provide a systematic model that could be generalized to describe entire families of ionic liquids. In order to meet that objective and to take into account the modular nature of ionic... 

An ionic liquid has to meet some prerequisites to be used for optical spectroscopy. This circumstance has been paid attention to in the literature [1], First of all, the ionic liquid must be optically pure. This puts high demands on the synthesis. To start... 

Noble RD, Gin DL, Koval C (2007) Ionic liquid materials for barrier applications. Abstracts of Papers, 234th ACS National Meeting, Boston, MA, United States, 19-23 August 2007 COLL-401... 

The above examples clearly demonstrate the potential of microwaves in ionic liquids as solvent and/or catalyst. Many well-known and new reactions have been discovered by this technology with evident advantages in most of the cases. The synergism arising from the combined use has enormous potential to meet the increasing demand for environmentally benign chemical processes. 

One of the important properties of ionic liquids is that they can be fine-tuned to meet specific solvation requirements to influence reaction outcomes. In recent years, the use of chiral ionic liquids as reaction media for asymmetric organic reactions and chiral discrimination as well as the optical resolution of racemic mixtures has dramatically increased. Unfortunately, there are only a few chiral ionic liquids that are designed, synthesized, and used as solvents for asymmetric reactions, leaving open an important area with huge potential and scope for further development. 

The technique of aqueous catalytic reactions has had such an impact on the field of more general two-phase reactions that scientists have now also proposed and tested other solutions. Fluorous systems (FBS, perfluorinated solvents cf. Section 7.2) and nonaqueous ionic liquids (NAILs, molten salts cf. Section 7.3) meet the demand for rapid separation of catalyst and product phases and, owing to the thermoreversibility of their phase behavior, have advantages in the homogeneous reaction and the heterogeneous separation. However, it is safe to predict that the specially tailored ligands necessary for these technologies will be too expensive for normal applications. Compared to the cheap and ubiquitous solvent water, with its unique combination of properties (cf. Table 1), other solvents may well remain of little importance, at least for industrial applications. Other ideas are mentioned in Section 7.6. 

---