TSIL

Viewed in conjunction with the solid-like, nonvolatile nature of ionic liquids, it is apparent that TSILs can be thought of as liquid versions of solid-supported reagents. Unlike solid-supported reagents, however, TSILs possess the added advantages of kinetic mobility of the grafted functionality and an enormous operational surface area (Figure 2.3-1). It is this combination of features that makes TSILs an aspect of ionic liquids chemistry that is poised for explosive growth. 

The incorporation of functionality into an ion slated for use in formulation of an ionic liquid is a usually a multi-step process. Consequently, a number of issues must be considered in planning the synthesis of the ion. The first of these is the choice of the cationic core. The core of a TSIL cation may be as simple as a single... 

The choice of reaction solvent is also of concern in the synthesis of new TSILs. Toluene and acetonitrile are the most widely used solvents, the choice in any given synthesis being dictated by the relative solubilities of the starting materials and products. The use of volatile organic solvents in the synthesis of ionic liquids is decidedly the least green aspect of their chemistry. Notably, recent developments in the area of the solventless synthesis of ionic liquids promise to improve this situation [10]. 

A variation on this overall synthetic approach allows the formation of related TSIL ureas by initial conversion of l-(3-aminopropyl)imida2ole into an isocyanate, followed by treatment with an amine and allcylating agent. This approach has been used to append both amino acids and nucleic acids onto the imidazolium cation skeleton [14]. 

While certain TSILs have been developed to pull metals into the IL phase, others have been developed to keep metals in an IL phase. The use of metal complexes dissolved in IL for catalytic reactions has been one of the most fruitful areas of IL research to date. LLowever, these systems still have a tendency to leach dissolved catalyst into the co-solvents used to extract the product of the reaction from the ionic liquid. Consequently, Wasserscheid et al. have pioneered the use of TSILs based upon the dissolution into a conventional IL of metal complexes that incorporate charged phosphine ligands in their stmctures [16-18]. These metal complex ions become an integral part of the ionic medium, and remain there when the reaction products arising from their use are extracted into a co-solvent. Certain of the charged phosphine ions that form the basis of this chemistry (e.g., P(m-C6H4S03 Na )3) are commercially available, while others may be prepared by established phosphine synthetic procedures. 

BMIM][PFg] and urea-appended (dashed lines) or thiourea-appended (solid lines) TSILs as the extracting phase. 

The TSIL used in this study has an ester moiety in its structure, which enables it to react in enzyme-catalyzed transesterification reaction. In the first part of the cycle, one of the enantiomers of the racemic alcohol is preferentially transformed into an ester of the IL-coupled acid. The other, unreacted enantiomer of the alcohol is then extracted, while the newly formed IL ester is treated with an excess of ethanol in the presence of the same enzyme. This process is accompanied by the regeneration of TSIL in the active form. The main advantage of the presented... 

Supported analogs of ionic liquid catalysts Task specific ionic liquids (TSIL) Telomerization in ILs... 

Recently, reports have appeared on a class of ILs known as task specific ionic liquids (TSIL). The term was introduced by J. H. Davis, Jr s group to refer to those ILs which have functional groups attached to them so as to give specific properties and functionalities. Thus, they not only perform specific functions like metal ion extraction,catalysisand capture of but also maintain the desired physical characteristics such as physical state, non-volatility, viscosity, etc. The implementation of TSILs further enhances the versatility of classical ILs where both reagent and medium are coupled. The union of reagent with medium has been... 

Electrophilic alkenes have been appended to imidazolium-type ILs for use in the Diels-Alder cycloaddition, 1,4-addition, Heck and Stetter reactions.Electrophilic alkenes containing Wang-type linkers were alkylated to imidazole followed by ion exchange and esterification giving the desired TSIL. Diels-Alder cycloaddition was carried out with 2,3-dimethylbutadiene and cyclopentadiene to give corresponding adducts. After washing with ether, transesterification resulted in cyclohexene derivatives. Scheme 29. 

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