A Review of Ionic Liquids, Their Limits and Applications

Abstract

Since environmental pollution caused by chemical and energy industries has increased for several decades, there is a social expectation that scientists and engineers try to design sustainable chemical processes, to generate less hazardous materials and more environmentally friendly sources of energy production. In this review the roles of Ionic Liquids (ILs) and IL based solvent systems as proposed alternative for conventional organic solvents are described. Since there are already many reviews on benefits of ILs, after a very brief review of ILs we focus mostly on aspects that are not covered in other reviews, in particular the known limits of these solvents. In addition, different methods to measure the physicochemical properties relevant to their use in energy storage applications such as fuel cells and batteries are introduced. The physicochemical properties that are reviewed are thermal properties, conductivity and chemical reactivity. The focus of the review is on the literature after 2008, with the exception of some important historic articles on ILs.

Share and Cite:

K. Ghandi, "A Review of Ionic Liquids, Their Limits and Applications," Green and Sustainable Chemistry, Vol. 4 No. 1, 2014, pp. 44-53. doi: 10.4236/gsc.2014.41008.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1] D. J. C. C. Concepción Jiménez-González, “Green Chemistry and Engineering—A Practical Design Approach,” John Wiley & Sons Inc., Hoboken, 2011, pp. 3-39.
[2] V. K. Ahluwalia, “Green Chemistry, Environmentally Benign Reaction,” CRC Press & Francis Group, Boca Raton, 2009.
[3] R. A. Sheldon, “Fundamentals of Green Chemistry: Efficiency in Reaction Design,” Chemical Society Reviews, Vol. 41, No. 4, 2012, pp. 1437-1451.
http://dx.doi.org/10.1039/c1cs15219j
[4] P. J. Dunn, “The Importance of Green Chemistry in Process Research and Development,” Chemical Society Reviews, Vol. 41, No. 4, 2012, pp. 1452-1461.
http://dx.doi.org/10.1039/c1cs15041c
[5] D. Ghernaout, B. Ghernaout and M. W. Naceur, “Embodying the Chemical Water Treatment in the Green Chemistry—A Review,” Desalination, Vol. 271, No. 1-3, 2011, pp. 1-10.
http://dx.doi.org/10.1016/j.desal.2011.01.032
[6] C. Capello, U. Fischer and K. Hungerbuhler, “What Is a Green Solvent? A Comprehensive Framework for the Environmental Assessment of Solvents,” Green Chemistry, Vol. 9, No. 9, 2007, pp. 927-934.
http://dx.doi.org/10.1039/b617536h
[7] C. S. Slater and M. Savelski, “A Method to Characterize the Greenness of Solvents Used in Pharmaceutical Manufacture,” Journal of Environmental Science and Health, Part A, Vol. 42, No. 11, 2007, pp. 1595-1605.
[8] E. M. Rundquist, C. J. Pink and A. G. Livingston, “Organic Solvent Nanofiltration: A Potential Alternative to Distillation for Solvent Recovery from Crystallisation Mother Liquors,” Green Chemistry, Vol. 14, No. 8, 2012, pp. 2197-2205. http://dx.doi.org/10.1039/c2gc35216h
[9] T. Welton, “Room-Temperature Ionic Liquids. Solvents for Synthesis and Catalysis,” Chemical Reviews, Vol. 99, No. 8, 1999, pp. 2071-2084.
http://dx.doi.org/10.1021/cr980032t
[10] N. Meine, F. Benedito and R. Rinaldi, “Thermal Stability of Ionic Liquids Assessed by Potentiometric Titration,” Green Chemistry, Vol. 12, No. 10, 2010, pp. 1711-1714.
http://dx.doi.org/10.1039/c0gc00091d
[11] S. Ahrens, A. Peritz and T. Strassner, “Tunable Aryl Alkyl Ionic Liquids (TAAILs): The Next Generation of Ionic Liquids. Angewandte Chemie International Edition, Vol. 48, No. 42, 2009, pp. 7908-7910.
http://dx.doi.org/10.1002/anie.200903399
[12] S. Gabriel and J. Weiner, “Ueber Einige Abkommlinge des Propylamins,” Berichte der Deutschen Chemischen Gesellschaft, Vol. 21, No. 2, 1888, pp. 2669-2679.
http://dx.doi.org/10.1002/cber.18880210288
[13] M. Armand, F. Endres, D. R. MacFarlane, H. Ohno and B. Scrosati, “Ionic-Liquid Materials for the Electrochemical Challenges of the Future,” NatureMaterials, Vol. 8, No. 8, 2009, 8, 621-629. http://dx.doi.org/10.1038/nmat2448
[14] A. Guerfi, M. Dontigny, P. Charest, M. Petitclerc, M. Lagacé, A. Vijh and K. Zaghib, “Improved Electrolytes for Li-Ion Batteries: Mixtures of Ionic Liquid and Organic Electrolyte with Enhanced Safety and Electrochemical Performance,” Journal of Power Sources, Vol. 195, No. 3, 2010, pp. 845-852.
http://dx.doi.org/10.1016/j.jpowsour.2009.08.056
[15] A. Lewandowski and A. Swiderska-Mocek, “Ionic Liquids as Electrolytes for Li-Ion Batteries—An Overview of Electrochemical Studies,” Journal of Power Sources, Vol. 194, No. 2, 2009, pp. 601-609.
http://dx.doi.org/10.1016/j.jpowsour.2009.06.089
[16] D. Weingarth, I. Czekaj, Z. Fei, A. Foelske-Schmitz, P. J. Dyson, A. Wokaun and R. Kotz, “Electrochemical Stability of Imidazolium Based Ionic Liquids Containing Cyano Groups in the Anion: A Cyclic Voltammetry, XPS and DFT Study,” Journal of The Electrochemical Society, Vol. 159, No. 7, 2012, pp. H611-H615.
http://dx.doi.org/10.1149/2.001207jes
[17] C. Wang, H. Luo, X. Luo, H. Li and S. Dai, “Equimolar CO2 Capture by Imidazolium-Based Ionic Liquids and Superbase Systems,” Green Chemistry, Vol. 12, No. 11, 2010, pp. 2019-2023.
http://dx.doi.org/10.1039/c0gc00070a
[18] J. Safaei-Ghomi, M. Emaeili, et al., “Mild and Efficient Method for Oxidation of Alcohols in Ionic Liquid Media,” Digest Journal of Nanomaterials and Biostructures, Vol. 5, No. 4, 2010, pp. 865-871.
[19] J.-I. Yu, H.-Y. Ju, K.-H. Kim and D.-W. Park, “Cycload- dition of Carbon Dioxide to Butyl Glycidyl Ether Using Imidazolium Salt Ionic Liquid as a Catalyst,” Korean Journal of Chemical Engineering, Vol. 27, No. 2, 2010, pp. 446-451.
http://dx.doi.org/10.1007/s11814-010-0074-1
[20] A. Sarkar, S. R. Roy, N. Parikh and A. K. Chakraborti, “Nonsolvent Application of Ionic Liquids: Organo-Catalysis by 1-Alkyl-3-methylimidazolium Cation Based Room-Temperature Ionic Liquids for Chemoselective N-tert-Butyloxycarbonylation of Amines and the Influence of the C-2 Hydrogen on Catalytic Efficiency,” The Journal of Organic Chemistry, Vol. 76, No. 17, 2011, pp. 7132-7140. http://dx.doi.org/10.1021/jo201102q
[21] D. Sarkar, R. Bhattarai, D. A. Headley and B. Ni, “A Novel Recyclable Organocatalytic System for the Highly Asymmetric Michael Addition of Aldehydes to Nitroolefins in Water,” Synthesis, Vol. 2011, 2011, pp. 1993-1997.
[22] S. Sowmiah, V. Srinivasadesikan, M.-C. Tseng and Y.-H. Chu, “On the Chemical Stabilities of Ionic Liquids,” Molecules, Vol. 14, No. 9, 2009, pp. 3780-3813.
http://dx.doi.org/10.3390/molecules14093780
[23] J. P. Canal, T. Ramnial, D. A. Dickie and J. A. C. Clyburne, “From the Reactivity of N-Heterocyclic Carbenes to New Chemistry in Ionic Liquids,” Chemical Communications, Vol. 2006, No. 17, 2006, pp. 1809-1818.
http://dx.doi.org/10.1039/b512462j
[24] V. K. Aggarwal, I. Emme and A. Mereu, “Unexpected Side Reactions of Imidazolium-Based Ionic Liquids in the Base-Catalysed Baylis-Hillman Reaction,” Chemical Communications, Vol. 2002, No. 15, 2002, pp. 1612-1613.
http://dx.doi.org/10.1039/b203079a
[25] L. Magna, Y. Chauvin, G. P. Niccolai and J.-M. Basset, “The Importance of Imidazolium Substituents in the Use of Imidazolium-Based Room-Temperature Ionic Liquids as Solvents for Palladium-Catalyzed Telomerization of Butadiene with Methanol,” Organometallics, Vol. 22, No. 22, 2003, pp. 4418-4425.
http://dx.doi.org/10.1021/om021057s
[26] N. D. Khupse and A. Kumar, “The Cosolvent-Directed Diels-Alder Reaction in Ionic Liquids,” The Journal of Physical Chemistry A, Vol. 115, No. 36, 2011, pp. 10211-10217. http://dx.doi.org/10.1021/jp205181e
[27] D. J. M. Snelders and P. J. Dyson, “Efficient Synthesis of β-Chlorovinylketones from Acetylene in Chloroaluminate Ionic Liquids,” Organic Letters, Vol. 13, No. 15, 2011, pp. 4048-4051.
http://dx.doi.org/10.1021/ol201182t
[28] L. Ford, F. Atefi, R. D. Singer and P. J. Scammells, “Grignard Reactions in Pyridinium and Phosphonium Ionic Liquids,” European Journal of Organic Chemistry, Vol. 2011, 2011, pp. 942-950.
[29] X. Y. Wu, “Facile and Green Synthesis of 1,4-Dihydropyridine Derivatives in n-Butyl Pyridinium Tetrafluoroborate,” Synthetic Communications, Vol. 42, No. 3, 2011, pp. 454-459.
http://dx.doi.org/10.1080/00397911.2010.525773
[30] A. R. Hajipour and M. Seddighi, “Pyridinium-Based Bronsted Acidic Ionic Liquid as a Highly Efficient Catalyst for One-Pot Synthesis of Dihydropyrimidinones,” Synthetic Communications, Vol. 42, No. 2, 2011, pp. 227-235. http://dx.doi.org/10.1080/00397911.2010.523488
[31] K. Pajuste, A. Plotniece, K. Kore, L. Intenberga, B. Ce- kavicus, D. Kaldre, G. Duburs and A. Sobolev, “Use of Pyridinium Ionic Liquids as Catalysts for the Synthesis of 3,5-Bis(dodecyloxycarbonyl)-1,4-dihydropyridine Derivative,” Central European Journal of Chemistry, Vol. 9, No. 1, 2011, pp. 143-148.
http://dx.doi.org/10.2478/s11532-010-0132-x
[32] K. Tsunashima, A. Kawabata, M. Matsumiya, S. Kodama, R. Enomoto, M. Sugiya and Y. Kunugi, “Low Viscous and Highly Conductive Phosphonium Ionic Liquids Based on Bis(fluorosulfonyl)amide Anion as Potential Electrolytes,” Electrochemistry Communications, Vol. 13, No. 2, 2011, pp. 178-181.
http://dx.doi.org/10.1016/j.elecom.2010.12.007
[33] S. A. Dake, R. S. Kulkarni, V. N. Kadam, S. S. Modani, J. J. Bhale, S. B. Tathe and R. P. Pawar, “Phosphonium Io- nic Liquid: A Novel Catalyst for Benzyl Halide Oxidation,” Synthetic Communications, Vol. 39, No. 21, 2009, pp. 3898-3904.
http://dx.doi.org/10.1080/00397910902840835
[34] H. Cao and H. Alper, “Palladium-Catalyzed Double Carbonylation Reactions of o-Dihaloarenes with Amines in Phosphonium Salt Ionic Liquids,” Organic Letters, Vol. 12, No. 18, 2010, pp. 4126-4129.
http://dx.doi.org/10.1021/ol101714p
[35] K. L. Luska, K. Z. Demmans, S. A. Stratton and A. Moores, “Rhodium Complexes Stabilized by Phosphine-Functionalized Phosphonium Ionic Liquids Used as Higher Alkene Hydroformylation Catalysts: Influence of the Phosphonium Headgroup on Catalytic Activity,” Dalton Transactions, Vol. 41, No. 43, 2012, pp. 13533-13540. http://dx.doi.org/10.1039/c2dt31797d
[36] A. Fan, G.-K. Chuah and S. Jaenicke, “Phosphonium Ionic Liquids as Highly Thermal Stable and Efficient Phase Transfer Catalysts for Solid-Liquid Halex Reactions,” Catalysis Today, Vol. 198, No. 1, 2012, pp. 300-304.
http://dx.doi.org/10.1016/j.cattod.2012.02.063
[37] N. D. Harper, N. D. Nizio, A. D. Hendsbee, J. D. Masuda, K. N. Robertson, L. J. Murphy, M. B. Johonson, C. C. Pye and J. A. C. Clyburne, “Survey of Carbon Dioxide Capture in Phosphonium-Based Ionic Liquids and End-Capped Polyethylene Glycol Using DETA (DETA = Diethylenetriamine) as a Model Absorbent,” Industrial & Engineering Chemistry Research, Vol. 50, No. 5, 2011, pp. 2822-2830.
http://dx.doi.org/10.1021/ie101734h
[38] K. Ghandi, “Process for the Production of Polystyrene and Novel Polymers in Phosphonium Ionic Liquids,” US Patent: 20,120,049,101, 2012.
[39] S. Cheng, M. Zhang, T. Wu, S. T. Hemp, B. D. Mather, R. B. Moore and T. E. Long, “Ionic Aggregation in Random Copolymers Containing Phosphonium Ionic Liquid Monomers,” Journal of Polymer Science Part A: Polymer Chemistry, Vol. 50, No. 1, 2012, pp. 166-173.
http://dx.doi.org/10.1002/pola.25022
[40] J. M. Lauzon, D. J. Arseneau, J. C. Brodovitch, J. A. C. Clyburne, P. Cormier, B. McCollum and K. Ghandi, “Generation and Detection of the Cyclohexadienyl Radical in Phosphonium Ionic Liquids,” Physical Chemistry Chemical Physics, Vol. 10, No. 39, 2008, pp. 5957-5962.
http://dx.doi.org/10.1039/b804800b
[41] B. Taylor, P. J. Cormier, J. M. Lauzon and K. Ghandi, “Investigating the Solvent and Temperature Effects on the Cyclohexadienyl Radical in an Ionic Liquid,” Physica B: Condensed Matter, Vol. 404, No. 5-7, 2009, pp. 936-939.
http://dx.doi.org/10.1016/j.physb.2008.11.224
[42] C. J. Bradaric, A. Downard, C. Kennedy, A. J. Robertson and Y. Zhou, “Industrial Preparation of Phosphonium Ionic Liquids,” Green Chemistry, Vol. 5, No. 2, 2003, pp. 143-152.
http://dx.doi.org/10.1039/b209734f
[43] M.-C. Tseng, H.-C. Kan and Y.-H. Chu, “Reactivity of Trihexyl(tetradecyl)phosphonium Chloride, a Room-Temperature Phosphonium Ionic Liquid,” Tetrahedron Letters, Vol. 48, No. 52, 2007, pp. 9085-9089.
http://dx.doi.org/10.1016/j.tetlet.2007.10.131
[44] K. J. Fraser and D. R. MacFarlane, “Phosphonium-Based Ionic Liquids: An Overview,” Australian Journal of Che- mistry, Vol. 62, No. 4, 2009, pp. 309-321.
http://dx.doi.org/10.1071/CH08558
[45] N. V. Plechkova, R. D. Rogers and K. R. Seddon, Eds., “Ionic Liquids: From Knowledge to Application,” American Chemical Society, Vol. 1030, 2009, p. 472.
[46] J. S. Wilkes, P. Wasserscheid and T. Welton, “Introduction,” In: P. Wasserscheid and T. Welton, Eds., Ionic Liquids in Synthesis, Wiley-VCH Verlag GmbH & Co. KGaA, Hoboken, 2007, pp. 1-6.
[47] J. D. Holbrey, R. D. Rogers, R. A. Mantz, P. C. Trulove, V. A. Cocalia, A. E. Visser, J. L. Anderson, J. L. Anthony, J. F. Brennecke, E. J. Maginn, T. Welton and R. A. Mantz, “Physicochemical Properties,” In: P. Wasserscheid and T. Welton, Eds., Ionic Liquids in Synthesis, Wiley-VCH Verlag GmbH & Co. KGaA, Hoboken, 2007, pp. 57-174.
[48] S. Sowmiah, C. I. Cheng and Y.-H. Chu, “Ionic Liquids for Green Organic Synthesis,” Current Organic Synthesis, Vol. 9, No. 1, 2012, pp. 74-95.
http://dx.doi.org/10.2174/157017912798889116
[49] M. J. A. Shiddiky and A. A. J. Torriero, “Application of Ionic Liquids in Electrochemical Sensing Systems,” Biosensors and Bioelectronics, Vol. 26, No. 5, 2011, pp. 1775-1787.
http://dx.doi.org/10.1016/j.bios.2010.08.064
[50] C. M. Gordon, “New Developments in Catalysis Using Ionic Liquids,” Applied Catalysis A: General, Vol. 222, No. 1-2, 2001, pp. 101-117.
http://dx.doi.org/10.1016/S0926-860X(01)00834-1
[51] F. Karadas, M. Atilhan and S. Aparicio, “Review on the Use of Ionic Liquids (ILs) as Alternative Fluids for CO2 Capture and Natural Gas Sweetening,” Energy & Fuels, Vol. 24, No. 11, 2010, pp. 5817-5828.
http://dx.doi.org/10.1021/ef1011337
[52] T. L. Greaves and C. J. Drummond, “Protic Ionic Liquids: Properties and Applications,” Chemical Reviews, Vol. 108, No. 1, 2007, pp. 206-237.
http://dx.doi.org/10.1021/cr068040u
[53] K. E. Johnson, R. M. Pagni and J. Bartmess, “Bronsted Acids in Ionic Liquids: Fundamentals, Organic Reactions, and Comparisons,” Monatshefte für Chemie, Vol. 138, No. 11, 2007, pp. 1077-1101.
http://dx.doi.org/10.1007/s00706-007-0755-6
[54] H. Markusson, J.-P. Belières, P. Johansson, C. A. Angell and P. Jacobsson, “Prediction of Macroscopic Properties of Protic Ionic Liquids by ab Initio Calculations,” The Journal of Physical Chemistry A, Vol. 111, No. 35, 2007, pp. 8717-8723. http://dx.doi.org/10.1021/jp072036k
[55] M. S. Miran, H. Kinoshita, T. Yasuda, M. A. B. H. Susan and M. Watanabe, “Hydrogen Bonds in Protic Ionic Liquids and Their Correlation with Physicochemical Properties,” Chemical Communications, Vol. 47, No. 47, 2011, pp. 12676-12678. http://dx.doi.org/10.1039/c1cc14817f
[56] A. Noda, M. A. B. H. Susan, K. Kudo, S. Mitsushima, K. Hayamizu and M. Watanabe, “Bronsted Acid-Base Ionic Liquids as Proton-Conducting Nonaqueous Electrolytes,” The Journal of Physical Chemistry B, Vol. 107, No. 17, 2003, pp. 4024-4033.
http://dx.doi.org/10.1021/jp022347p
[57] K. Fumino, A. Wulf and R. Ludwig, “Hydrogen Bonding in Protic Ionic Liquids: Reminiscent of Water,” Angewandte Chemie International Edition, Vol. 48, No. 17, 2009, pp. 3184-3186.
http://dx.doi.org/10.1002/anie.200806224
[58] D. Wakeham, A. Nelson, G. G. Warr and R. Atkin, “Probing the Protic Ionic Liquid Surface Using X-Ray Reflectivity,” Physical Chemistry Chemical Physics, Vol. 13, No. 46, 2011, pp. 20828-20835.
http://dx.doi.org/10.1039/c1cp22351h
[59] D. F. Evans, S.-H. Chen, G. W. Schriver and E. M. Arnett, “Thermodynamics of Solution of Nonpolar Gases in a Fused Salt. Hydrophobic Bonding Behavior in a Non- aqueous System,” Journal of the American Chemical Society, Vol. 103, No. 2, 1981, pp. 481-482.
http://dx.doi.org/10.1021/ja00392a049
[60] D. F. Evans, A. Yamauchi, G. J. Wei and V. A. Bloomfield, “Micelle Size in Ethylammonium Nitrate as Determined by Classical and Quasi-Elastic Light Scattering,” The Journal of Physical Chemistry, Vol. 87, No. 18, 1983, pp. 3537-3541.
http://dx.doi.org/10.1021/j100241a035
[61] A. H. Beesley, D. F. Evans and R. G. Laughlin, “Evidence for the Essential Role of Hydrogen Bonding in Promoting Amphiphilic Self-Assembly: Measurements in 3-Methylsydnone,” The Journal of Physical Chemistry, Vol. 92, No. 3, 1988, pp. 791-793.
http://dx.doi.org/10.1021/j100314a039
[62] L. Timperman, P. Skowron, A. Boisset, H. Galiano, D. Lemordant, E. Frackowiak, F. Beguin and M. Anouti, “Triethylammonium Bis(tetrafluoromethylsulfonyl)amide protic Ionic Liquid as an Electrolyte for Electrical Double-Layer Capacitors,” Physical Chemistry Chemical Phy- sics, Vol. 14, No. 22, 2012, pp. 8199-8207.
http://dx.doi.org/10.1039/c2cp40315c
[63] Z. Du, Z. Li, S. Guo, J. Zhang, L. Zhu and Y. Deng, “Investigation of Physicochemical Properties of Lactam-Based Bronsted Acidic Ionic Liquids,” The Journal of Physical Chemistry B, Vol. 109, No. 41, 2005, pp. 19542-19546. http://dx.doi.org/10.1021/jp0529669
[64] B. Schwenzer, N. S. Kerisit and M. Vijayakumar, “Anion Pairs in Room Temperature Ionic Liquids Predicted by Molecular Dynamics Simulation, Verified by Spectroscopic Characterization,” RSC Advances, Vol. 4, No. 11, 2014, pp. 5457-5464.
[65] B. Nuthakki, T. L. Greaves, I. Krodkiewska, A. Weerawardena, M. I. Burgar, R. J. Mulder and C. J. Drummond, “Protic Ionic Liquids and Iconicity,” Australian Journal of Chemistry, Vol. 60, No. 1, 2007, pp. 21-28.
http://dx.doi.org/10.1071/CH06363
[66] J. Stoimenovski, E. I. Izgorodina and D. R. MacFarlane, “Ionicity and Proton Transfer in Protic Ionic Liquids,” Physical Chemistry Chemical Physics, Vol. 12, No. 35, 2010, pp. 10341-10347.
http://dx.doi.org/10.1039/c0cp00239a
[67] M. Yoshizawa, W. Xu and C. A. Angell, “Ionic Liquids by Proton Transfer: Vapor Pressure, Conductivity, and the Relevance of ΔpKa from Aqueous Solutions,” Journal of the American Chemical Society, Vol. 125, No. 50, 2003, pp. 15411-15419.
http://dx.doi.org/10.1021/ja035783d
[68] C. F. Poole, “Chromatographic and Spectroscopic Methods for the Determination of Solvent Properties of Room Temperature Ionic Liquids,” Journal of Chromatography A, Vol. 1037, No. 1-2, 2004, pp. 49-82.
http://dx.doi.org/10.1016/j.chroma.2003.10.127
[69] W. Wang, L. Shao, W. Cheng, J. Yang and M. He, “Bronsted Acidic Ionic Liquids as Novel Catalysts for Prins Reaction,” Catalysis Communications, Vol. 9, No. 3, 2008, pp. 337-341.
http://dx.doi.org/10.1016/j.catcom.2007.07.006
[70] S.-Y. Lee, A. Ogawa, M. Kanno, H. Nakamoto, T. Yasuda and M. Watanabe, “Nonhumidified Intermediate Temperature Fuel Cells Using Protic Ionic Liquids,” Journal of the American Chemical Society, Vol. 132, No. 28, 2010, pp. 9764-9773.
http://dx.doi.org/10.1021/ja102367x
[71] A. Fernicola, S. Panero and B. Scrosati, “Proton-Conducting Membranes Based on Protic Ionic Liquids,” Journal of Power Sources, Vol. 178, No. 2, 2008, pp. 591-595.
http://dx.doi.org/10.1016/j.jpowsour.2007.08.079
[72] H. Ye, J. Huang, J. J. Xu, N. K. A. C. Kodiweera, J. R. P. Jayakody and S. G. Greenbaum, “New Membranes Based on Ionic Liquids for PEM Fuel Cells at Elevated Temperatures,” Journal of Power Sources, Vol. 178, No. 2, 2008, pp. 651-660.
http://dx.doi.org/10.1016/j.jpowsour.2007.07.074
[73] H. Nakamoto and M. Watanabe, “Bronsted Acid-Base Ionic Liquids for Fuel Cell Electrolytes,” Chemical Communications, No. 24, 2007, pp. 2539-2541.
http://dx.doi.org/10.1039/b618953a
[74] N. B. Darvatkar, A. R. Deorukhkar, S. V. Bhilare and M. M. Salunkhe, “Ionic Liquid-Mediated Knoevenagel Condensation of Meldrum’s Acid and Aldehydes,” Synthetic Communications, Vol. 36, No. 20, 2006, pp. 3043-3051.
http://dx.doi.org/10.1080/00397910600775218
[75] E. Janus, I. Goc-Maciejewska, M. Lozyński and J. Pernak, “Diels-Alder Reaction in Protic Ionic Liquids,” Tetrahedron Letters, Vol. 47, No. 24, 2006, pp. 4079-4083.
http://dx.doi.org/10.1016/j.tetlet.2006.03.172
[76] A. Zhu, T. Jiang, D. Wang, B. Han, L. Liu, J. Huang, J. Zhang and D. Sun, “Direct Aldol Reactions Catalyzed by 1,1,3,3-Tetramethylguanidine Lactate without Solvent,” Green Chemistry, Vol. 7, No. 7, 2005, pp. 514-517.
http://dx.doi.org/10.1039/b501925g
[77] H. Zhou, J. Yang, L. Ye, H. Lin and Y. Yuan, “Effects of Acidity and Immiscibility of Lactam-Based Bronsted-Acidic Ionic Liquids on Their Catalytic Performance for Esterification,” Green Chemistry, Vol. 12, No. 4, 2010, pp. 661-665. http://dx.doi.org/10.1039/b921081d
[78] L. C. Henderson and N. Byrne, “Rapid and Efficient Protic Ionic Liquid-Mediated Pinacol Rearrangements under Microwave Irradiation,” Green Chemistry, Vol. 13, No. 4, 2011, pp. 813-816.
http://dx.doi.org/10.1039/c0gc00916d
[79] X. Li, W. Eli and G. Li, “Solvent-Free Synthesis of Benzoic Esters and Benzyl Esters in Novel Bronsted Acidic Ionic Liquids under Microwave Irradiation,” Catalysis Communications, Vol. 9, No. 13, 2008, pp. 2264-2268.
http://dx.doi.org/10.1016/j.catcom.2008.05.015
[80] H. Shi, W. Zhu, H. Li, H. Liu, M. Zhang, Y. Yan and Z. Wang, “Microwave-Accelerated Esterification of Salicylic Acid Using Bronsted Acidic Ionic Liquids as Catalysts,” Catalysis Communications, Vol. 11, No. 7, 2010, pp. 588-591. http://dx.doi.org/10.1016/j.catcom.2009.12.025
[81] X. Tong and Y. Li, “Efficient and Selective Dehydration of Fructose to 5-Hydroxymethylfurfural Catalyzed by Bronsted-Acidic Ionic Liquids,” ChemSusChem, Vol. 3, No. 3, 2010, pp. 350-355.
http://dx.doi.org/10.1002/cssc.200900224
[82] P. Gabbott, “Principles and Applications of Thermal Analysis,” Wiley, Hoboken, 2008.
http://dx.doi.org/10.1002/9780470697702
[83] M. Sorai and N. N. Gakkai, “Comprehensive Handbook of Calorimetry and Thermal Analysis,” Wiley, Hoboken, 2004.
[84] J.-P. Belieres and C. A. Angell, “Protic Ionic Liquids: Preparation, Characterization, and Proton Free Energy Level Representation,” The Journal of Physical Chemistry B, Vol. 111, No. 18, 2007, pp. 4926-4937.
http://dx.doi.org/10.1021/jp067589u
[85] M. A. B. H. Susan, A. Noda, S. Mitsushima and M. Watanabe, “Bronsted Acid-Base Ionic Liquids and Their Use as New Materials for Anhydrous Proton Conductors,” Chemical Communications, No. 8, 2003, pp. 938-939.
http://dx.doi.org/10.1039/b300959a
[86] S. R. Varma, “Solvent-Free Organic Syntheses Using Supported Reagents and Microwave Irradiation,” Green Chemistry, Vol. 1, No. 1, 1999, pp. 43-55.
http://dx.doi.org/10.1039/a808223e
[87] A. Davoodnia, M. M. Heravi, Z. Safavi-Rad and N. Tavakoli-Hoseini, “Green, One-Pot, Solvent-Free Synthesis of 1,2,4,5-Tetrasubstituted Imidazoles Using a Bronsted Acidic Ionic Liquid as Novel and Reusable Catalyst,” Synthetic Communications, Vol. 40, No. 17, 2010, pp. 2588-2597.
http://dx.doi.org/10.1080/00397910903289271
[88] T. L. Greaves, A. Weerawardena, C. Fong, I. Krodkiewska and C. J. Drummond, “Protic Ionic Liquids: Solvents with Tunable Phase Behavior and Physicochemical Properties,” The Journal of Physical Chemistry B, Vol. 110, No. 45, 2006, pp. 22479-22487.
http://dx.doi.org/10.1021/jp0634048
[89] A. Davoodnia, M. Bakavoli, R. Moloudi, N. Tavakoli-Hoseini and M. Khashi, “Highly Efficient, One-Pot, Solvent-Free Synthesis of 2,4,6-Triarylpyridines Using a Bronsted Acidic Ionic Liquid as Reusable Catalyst,” Monatshefte für Chemie, Vol. 141, No. 8, 2010, pp. 867-870.
http://dx.doi.org/10.1007/s00706-010-0329-x
[90] S. Nazari, K. Ghandi, S. B. Cameron and M. B. Johonson, “Physicochemical Properties of Imidazo Pyridine Protic Ionic Liquids,” Journal of Materials Chemistry A, Vol. 1, No. 38, 2013, pp. 11570-11579.

Copyright © 2023 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.