Novel lactam-cation-based Bronsted acid ionic liquids (ILs) were prepared through a simple and atom-economic neutralization reaction between a lactam, such as caprolactam and butyrolactam, and a Bronsted acid, HX, where X is BF4-, CF3COO-, phCOO(-), ClCH2COO-, NO3-, or H2PO4-. The density, viscosity, acidic scale, electrochemical window, temperature dependency of ionic conductivity, and thermal property of these ILs were measured and investigated in detail. The results show that protonated caprolactam tetrafluoroborate (CPBF) has a relatively strong acidity with -0.22 of Hammett acidic scale Ho and caprolactam trifluoroacetate (CPTFA) and pyrrolidonium trifluoroacetate (PYTFA) ILs possess very low viscosities, that is, 28 cP and 11 cP, respectively. An investigation of thermal property showed that a wide liquid range (up to -90 degrees C), moderate thermal stability (up to 249 degrees C for 10% of decomposition), and complex polymorphism were observed in these ILs. In comparison to imidazolium-cation-based ILs, the lactam-cation-based Bronsted acid ILs have a relatively lower cost, lower toxicity, and comparable ion conductivity and heat storage density (more than 200 MJ/m(3)). They have wide applicable perspectives for fuel cell devices, thermal transfer fluids, and acid-catalyzed reaction media and catalysts as replacements of conventional inorganic acids.

★★★★☆ Zhengyin Du, Zuopeng Li, Shu Guo, Juan Zhang, Laiying Zhu, and Youquan Deng. J. Phys. Chem. B 2005, 109, 19542-19546

A new concept of designing and synthesizing highly dispersed ionic liquids was developed through physical confinement or encapsulation of them into silica gel matrix with sol–gel process. A series of silica gel confined ionic liquids were synthesized through this process and characterized by diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS) and FTRaman analysis, and abnormal FT-IR and FTRaman spectra were observed. The silica gel matrixes confined ionic liquid BMImBF4 were further characterized by BET analysis after the ionic liquid was almost completely washed out by acetone under refluxing conditions and meso-porous silica gel matrixes were obtained according to the N2 adsorption measurements, which suggested that the particle-size of the dispersed ionic liquids was in nano-scale. In consideration of the results obtained together, it could be found that the abnormal FT-IR and FTRaman spectra were changed with the poresize of the silica gel matrix. For example, obvious abnormal FT-IR and FTRaman spectra appeared when the particle-size of ionic liquid BMImBF4 is smaller than 11 nm while they disappeared again if the corresponding particle-size >11 nm. These results indicated that nano-effect, or restriction effect, produced from the nano-pores of silica gel was the reason for the abnormal FT-IR and FTRaman spectra.

★★★☆☆ Keywords: Ionic liquids; Silica gel; Abnormal spectra; Nano-material; Characterization

★★★☆☆ F. Shi, Y. Deng / Spectrochimica Acta Part A 62 (2005) 239–244.

Several acid-functional ionic liquids were physically confined into the silica gel through a sol–gel process and used as effective catalysts for deoximation reactions, which proceeded under ambient temperatures without addition of any co-catalysts or oxidizing and reducing agents.

★★★★☆ D. Li et al. / Tetrahedron Letters 45 (2004) 265–268.

The interactions between heavy metals (vanadium and nickel) and kaolin had been investigated by X-ray diffraction and MAT test. In the process of phase transformation of kaolin containing 1–5% vanadium, vanadium-mullite phase emerged surprisingly at 660–700 ◦C. The unit cell size of the mullite was found to increase with increment of vanadium content. As compared with hydro-kaolin, acid-modified kaolin(AMK) and caustic-modified kaolin (CMK) reacted with vanadium to form much more mullite; CMK could even be reacted with nickel to form a rather stable NiAl10O16 compound, and this compound protected zeolite in fluid catalytic cracking catalyst effectively. The catalyst containing AMK had greaterMAT activity retention than that of the contrastive catalyst with hydro-kaolin in the identical level of heavy metal contamination.

★★★☆☆ Keywords: Kaolin; Nickel; FCC catalyst; Vanadium; Mullite; Eutectic; Unit cell size

★★★☆☆ Conghua Liu, Youquan Deng, Yuanqing Pan, Shygin Zheng, Xionghou Gao. Applied Catalysis A: General 257 (2004) 145–150.

Reactions of propargylic alcohols with CO2 in a [BMIm][PhSO3]/CuCl catalytic system to produce the corresponding R-methylene cyclic carbonates were conducted with high yields. Mild reaction conditions, enhanced rates, improved yields, and recyclable ionic liquid catalyst systems are the remarkable features exhibited in this process. Furthermore, the use of large amounts of tertiary amines as well as nitrogen-containing organic solvent as employed in previously studies was avoided.

★★★★☆ Yanlong Gu, Feng Shi, and Youquan Deng. J. Org. Chem. 2004, 69, 391-394.

The solubilities of taurine (2-aminoethanesulfonic acid (H2NCH2CH2SO3H)) and sodium sulfate in a series of room temperature ionic liquids were examined, and a novel and greener separation method combined with chlorinated dialkylimidazolium ionic liquid as leaching reagent and organic solvent as precipitating reagent was developed. Using such process, selective separation of taurine from solid mixture containing large amount of sodium sulfate could be realized with 67–98.5% of single separation yield. The recycling of ionic liquid and organic solvent used in this separation process is possible.

★★★☆☆ Keywords: Ionic liquid; Leaching separation; Taurine; Solubility; Sodium sulfate

★★★☆☆ Y. Gu et al. / Separation and Purification Technology 35 (2004) 153–159.

Under mild conditions and without any additional organic solvents, Beckmann rearrangement of ketoximes was performed in a novel task-specific ionic liquid consisting sulfonyl chloride. Especially for the conversion of cyclohexanone oxime to e-caprolactam, e-caprolactam has good solubility in water while the task-specific ionic liquid is immiscible with water, therefore, e-caprolactam could be easily separated from the reaction system by water extraction.

★★★★☆ J. Gui et al. / Tetrahedron Letters 45 (2004) 2681–2683.

Addition reactions of aliphatic acids with olefins to give corresponding esters have been investigated using SO3H-functionalized ionic liquids as dual catalyst–solvent. The isolation of the desired products could be achieved via simple decantation and ionic liquids could be reused continuously after dried in vacuum (5–12 mmHg) at ca. 80 ◦C.

★★★☆☆ Y. Gu et al. / Journal of Molecular Catalysis A: Chemical 212 (2004) 71–75.

Several acid functional ionic liquids, in which cations possess two adjacent acid sites, were synthesized and used for the acetalization of aldehydes with good catalytic performance under mild reaction conditions.

★★★★☆ Dongmei Li, Feng Shi, Jiajian Peng, Shu Guo, and Youquan Deng. J. Org. Chem. 2004, 69, 3582-3585.

Cracking of FCC naphtha has been investigated on the model catalysts containing ZSM-5 (Si/Al2 = 50, 500), Zn-ZSM-5 (Si/Al2 = 50) and USY. The presence of ZSM-5 and USY causes a tremendous decrease in olefins of gasoline fraction, leading to an enrichment of the aromatics in liquid product. It is evidently that aromatics are generated from lower olefins. The property of lower silica-to-alumina ratio of ZSM-5 and Zn modification enhance the aromatization process for higher cracking reactivity and dehydrogenation. The result of evaluation in confined fluid bed apparatus (CFBA) with the mixture of VGO and VTB as feed further confirms the aromatics generation in cracking reaction stimulated by ZSM-5 additive over base catalysts with different hydrogen transfer activity. Based on these results, relations between scission and aromatization in FCC catalyst containing ZSM-5 zeolite could be proposed. The suggested reaction path could better explain the reasons that effectiveness of ZSM-5 additive to lighter olefins is more profound in base catalyst of low hydrogen transfer activity and why so many researchers had not observed the aromatics generation motivated by ZSM-5 additive in catalytic cracking reaction.

★★★☆☆ Keywords: ZSM-5; Aromatics generation; Hydrogen transfer activity; Lighter olefins; FCC catalyst

★★★☆☆ C. Liu et al. / Journal of Molecular Catalysis A: Chemical 215 (2004) 195–199.