Imidazolium trifluoroacetate

Ma, C.A. et ah. Electro-oxidation of formaldehyde on polyaniline prepared in 1-ethyl-imidazolium trifluoroacetate, Electrochem. Solid-State Lett., 8, G122, 2005. 

Gomez et al. have employed imidazolium trifluoroacetate as a replacement for tetrazole in synthesis of t-butyl ester-protected phosphotyrosine (55) (Scheme 10). ... 

Diels-Alder reactions Neutral ionic liquids have been found to be excellent solvents for the Diels-Alder reaction. The first example of a Diels-Alder reaction in an ionic liquid was the reaction of methyl acrylate with cyclopentadiene in [EtNH3][N03] [40], in which significant rate enhancement was observed. Howarth et al. investigated the role of chiral imidazolium chloride and trifluoroacetate salts (dissolved in dichloromethane) in the Diels-Alder reactions between cyclopentadiene and either crotonaldehyde or methacroline [41]. It should be noted that this paper describes one of the first examples of a chiral cationic ionic liquid being used in synthesis (Scheme 5.1-17). The enantioselectivity was found to be < 5 % in this reaction for both the endo (10 %) and the exo (90 %) isomers. 

Several acids salts have been proposed to replace tetrazole as the activator of phosphoroamidite coupling with alcohols. The most popular are benzimida-zolium [20a], imidazolium [20b], AT-methylimidazolium [20c], AT-methylani-line [20h] trifiates, pyridinium hydrochloride [20d,e], hydrobromide [20e], tetrafluorborate [20f], trifluoroacetate [20g] and 2,4,6-collidine trifiuoroac-etate [20i]. 

Ionic liquids are a class of solvents and they are the subject of keen research interest in chemistry (Freemantle, 1998). Hydrophobic ionic liquids with low melting points (from -30°C to ambient temperature) have been synthesized and investigated, based on 1,3-dialkyl imidazolium cations and hydrophobic anions. Other imidazolium molten salts with hydrophilic anions and thus water-soluble are also of interest. NMR and elemental analysis have characterized the molten salts. Their density, melting point, viscosity, conductivity, refractive index, electrochemical window, thermal stability, and miscibility with water and organic solvents were determined. The influence of the alkyl substituents in 1,2, 3, and 4(5)-positions on the imidazolium cation on these properties has been scrutinized. Viscosities as low as 35 cP (for l-ethyl-3-methylimi-dazolium bis((trifluoromethyl)sulfonyl)amide (bis(triflyl)amide) and trifluoroacetate) and conductivities as high as 9.6 mS/cm were obtained. Photophysical probe studies were carried out to establish more precisely the solvent properties of l-ethyl-3-methyl-imidazolium bis((trifluoromethyl)sulfonyl)amide. The hydrophobic molten salts are promising solvents for electrochemical, photovoltaic, and synthetic applications (Bon-hote et al., 1996). 

Separation science focuses on room temperature ionic liquids (RTlLs), salts that are liquid at ambient temperature. They have been studied as extracting solvents, stationary and mobile phases, mobile phase additives, and other uses. Common RTILs consist of a bulky nitrogen- or phosphorus-containing organic cation (pyridinium or pyrrolidinium, alkyl-imidazolium, ammonium or phosphonium) and a variety of organic and inorganic anions (triflate, dicyanamide, trifluoroacetate, acetate trifluo-romethylsulfate, nitrate, perchlorate, bromide, chloride, chloroaluminate, tetrafluo-roborate, hexafluorophosphate). 

Various additives have been added to PFSA membranes to either replace the water or to retain the water at higher temperatures. Nafion has been swollen with phosphoric acid and a conductivity of 0.05 S/cm has been achieved at 150°C. Unfortimately, the anode fails after a short period of time in these membranes so no successful FC tests have been run. 1-Butyl,3-methyl imidazolium triflate and tetrafluoroborate have also been used to swell Nafion giving a conductivity of 0.1 S/cm at 180°C. Nafion has also been swollen with heterocycle solutions, imidazole, and imidazolium salts in trifluoroacetate and trifluoro methane sulfonate solution, although the reported conductivities are more modest, 10 S/cm at 100°C. Acetic acid and tetra-n-butylammonium chloride solutions of the heteropoly acid (HPA), 12-phosphotungstic acid (PTA), have all been used with Nafion giving improved FC performance at 110°C and 120°C, respectively, vs. the undoped PFSA. ... 

The potential detrimental effect of halide has been described previously. A first alternative to the two-step synthesis is the direct alkylation of N-alkylimidazole. H owever, the range of available alkylating reagents is limited and they are sometimes expensive. Two-step syntheses of ILs which do not use imidazolium halide as an intermediate were then developed. For example, Seddon described the reaction of N-alkylimidazole with ethyl trifluoroacetate, which leads to imidazolium trifluoro-... 

Pyridine is considered as one of the commonest heterocycles among nitrogen-containing heterocychc compounds. Substituent effects in meta-and para-X-substituted pyridines (with X = OMe and Me) on their basicity have been studied in water and ionic hquid (IL, l-buthyl-3-methyl-imidazolium hexafluorophosphate) (2010JOC(75)3912). The equibbrimn constants were evaluated by spectrophotometric titration of pyridine solution with trifluoroacetic acid. The results of the Hammett approach (Eqn (1)), applied to aU studied systems, allow one to state that pyridine basicity is almost twice as less sensitive to the substituent effect in IL than in water (Figure 2). 

IV-Phenylimidazolium triflate IV-Phenylimidazolium perchlorate 2-(Bromo)-4,5-(dicyano)imidazole IV-Methylbenzimidazolium triflate Pyridinium tetrafluoroborate IV-Methylanilinium trifluoroacetate lV-(p-Acetylphenyl)imidazolium triflate IV-Phenylimidazolium tetrafluoroborate ImidazoUum perchlorate 5-(/t-Nitrophenyl)-l//-tetrazole 4,5- (Dicy ano)imidazDle 4-(Phenyl)imidazDlium triflate Benzimidazolium tetrafluoroborate Imidazolium tetrafluoroborate Imidazolium triflate Benzimidazolium triflate 2-(Phenyl)imidazolium triflate A-Methylimidazolium triflate 4-(Methyl)imidazolium triflate l//-Tetrazole... 

A-heterocycles like imidazole as proton solvents were used to replace water in Nafion and found to significantly improve the proton conductivity of these membranes under anhydrous conditions at elevated temperatures. Stm et al. [90] were among the first workers to prepare the water-free Nafion membranes by swelling them in imidazole and imidazolium salt solutions (e.g., trifluoroacetate and trifluor-omethane sulfonate). Yang et al. [91] reported that a recast Nafion membrane containing 10 wt % imidazole exhibited a conductivity of as high as 0.1 S cm at 160-180 °C. On the other hand, soaking Nafion membranes in either molten imidazole [91] or imidazole solutions in methanol [91, 92] led to much lower cmiductivities of 10 S cm IH-1,2,4-triazole [93, 94], benzimidazole [93], 3-amino-1,2,4-triazole [94], and 5-aminotetrazole [94] have also been explored. These efforts are summarized in Table 3.1. 

Group 8 cyclic C cyclic in imidazolium or pyridinium s cation Group 20 ACE, trifluoroacetate... 

---