Task Specific Ionic Liquid Amine

Supported Ionic Platforms for Scavenging Electrophiles 8.3.4.1 Task Specific Ionic Liquid Amine 

An alternative approach to scavenging that does not utilize polyethylene glycol) (PEG), silica or fluorous tags is ionic liquids. One such account was the application of quaternary ammonium salts bearing amino functionality reported by Stien in 2002 [73]. These high-load scavengers were utilized in scavenging excess electro- 

Wang reported an example of a water soluble, ionic scavenger for the sequestration of excess acid chlorides in the synthesis of benzamides and sulfonamides [76]. 

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Gutowski KE, Maginn EJ (2008) Amine-functionalized task-specific ionic liquids a mechanistic explanation for the dramatic increase in viscosity upon complexation with CO from molecular simulation. J Am Chem Soc 130 14690-14704... 

Scheme 2.3-2 Representative syntheses of functionalized cations for task-specific ionic liquids, beginning with 1-(3-aminopropyl)imidazole. Step one of the synthetic transformations is the conversion of the primary amine moiety to the functional group of interest. Step two of the process is the quaternization ofthe imidazole ring by alkylation at N(3).

Various synthetic methods for ILs have been reviewed in detail [14]. In order to provide a specialized capability for an IL, functional groups need to be present in the cation or anion. Such functionalized ILs are commonly termed task-specific ionic liquids (TSlLs) [15]. Generally, the IL cation is the favored functionalization site because of the wide variety of available natural products that already contain the desired moieties. These compounds are usually transformed into cations via a quatemization reaction between a nucleophilic group such as an amine, V-hetero-cycle, phosphine, and an alkyl halide [16]. 

Davis introduced some complimentary strategies for the synthesis of functional ionic liquids, by the inclusion of functional group (FG) to the cationic skeleton, in his review (Davis, 2004). The called "task-specific ionic liquids" have been synthesized, for example, by N-alkylation of alkyl halides covalently linked to FG with appropriate Lewis bases (e.g., imidazole, amine, phosphine, and sulfide Scheme 2a), accompanied by the anion metathesis to realize ionic liquids. One of other strategies is to use Michael reaction of alkyl vinyl ketones linked to FG with tertiary cations, as in Scheme 2b (Wasserscheid et al., 2003). It is noteworthy that this facile one-pot reaction dispenses with the need for a further anion metathesis step and are free from haUde-containing by-product. 

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