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Final Report: Solvent Properties of Ionic Liquids: Enabling the Assessment of Ionic Liquids for Clean, Environmentally Benign Technologies
EPA Grant Number: R831432Title: Solvent Properties of Ionic Liquids: Enabling the Assessment of Ionic Liquids for Clean, Environmentally Benign Technologies
Investigators: Rogers, Robin D. , Holbrey, John D.
Institution: University of Alabama - Tuscaloosa
EPA Project Officer: Richards, April
Project Period: December 22, 2003 through December 21, 2006
Project Amount: $325,000
RFA: Technology for a Sustainable Environment (2003)
Research Category: Pollution Prevention/Sustainable Development
Description:
Objective:Room temperature ionic liquids (RTIL) are emerging as novel replacements for volatile organic compounds (VOCs) traditionally used as industrial solvents; however, the basic science involved with fully characterizing these systems (physical properties, solubilities, partitioning, toxicities, costs, etc.) may be artificially holding back utilization of these green solvents. During this award period, the research focused on generating new data leading to the development of a fundamental scientific-engineering knowledge base in RTIL properties, toxicological data, as well as novel materials, all of which are prerequisites to the development of new pollution prevention technologies using these neoteric solvents. The highlights of this work are listed below.
Summary/Accomplishments (Outputs/Outcomes):The suitability of ionic liquids as solvent replacements was studied for:
Crystallization
A description of the current state-of-the-art techniques involving ionic liquids in crystallizations was published by Reichert, et al., 2006 (Figure 1). It is stated that, despite that there is a long way to go towards a full understanding of the role of ionic liquids (ILs), some useful aspects have been identified. It is not only possible to use the comparably wide electrochemical window for electrocrystallization, it is also possible to incorporate the IL (either one of the ions or the complete formula) in the crystal, and therefore a huge variety of new structures is accessible. Because of the inherent tunability of ILs, a tailor-made microenvironment for crystallization processes can be envisioned. Traditional approaches in crystallization techniques—for example, thermal shift, slow evaporation of a co-solvent, etc.—can be used with ILs as solvents. Crystal structures of 1,3-dimethylimidazolium and 1,2,3-triethylimidazolium bistrifylimide (TFSI) structures have been characterized by single crystal X-ray diffraction (Holbrey, et al., 2004). The TFSI anion in the lower-melting 1,3-dimethylimidazolium adopts a higher energy, less stable cis conformation than the trans conformation observed for 1,2,3-triethylimidazolium and all other characterized organic TFSI salts. The observation of the cis and trans anion conformations in the different crystalline salts may have important implications in developing a better understanding of the factors governing the crystal–liquid transition (melting point and lattice energies) in these and other ILs and low-melting organic salts. New crystal structures have been obtained using ILs as solvents (Holbrey, et al., 2006). This is expected to generate new insights and knowledge in separation techniques, for example, the separation of heavy metals from nuclear waste and other applications. ILs as suitable media for protein crystallization have been developed and tested (Pusey, et al., 2007).
Figure 1.
The Formation of New Materials
Conductive Hydrogels. The solution properties of a free-standing PEG hydrogel constructed from the reaction of functionalized PEG monomers have been studied with inclusion of conductive ILs (Klingshirn, et al., 2004; Figure 2). This is the first time that a cross-linked PEG matrix, like this, has been used to gel non-aqueous solvents. Another approach in the preparation of gel-like materials makes use of 1-butyl-3-methylimidazolium chloride ([bmim]Cl) as a drying control agent in the synthesis of silica sol-gel materials. A dependence of the surface size of calcinated gels on the IL concentration was observed (Klingshirn, et al., 2005a).
Figure 2.
Bioactive Films and Composite Materials. Our discovery that cellulose dissolves in 1-butyl-3-methylimidazolium chloride ([bmim]Cl) led us to investigate cellulose-catalyzed hydrolysis of cellulose in [bmim]Cl. A systematic study of a new method for introducing enzymes into cellulosic matrices which can subsequently be formed into membranes, films, or beads has been developed (Turner, et al., 2004; Figure 3). Blending cellulose with different Jeffamines or immobilizing laccase on cellulose support (Turner, et al., 2005) led to materials that could be used as catalysts. Studying cellulose dissolved in 1-butyl-3-methylimidazolium chloride ([bmim]Cl) by 13C-nuclear magnetic resonance (NMR) spectroscopy techniques allowed the conclusion that this natural polymer behaves in the same way as in water if dissolved in this IL (Moulthrop, et al., 2005). The system [bmim]Cl/cellulose has further been studied using 35/37Cl-NMR techniques (Remsing, et al., 2006). It could be shown that the interaction between the chloride anion and the cellulose hydroxyl groups is crucial for the understanding of the solvent properties for this IL/substrate couple. Magnetic cellulose fibers have been prepared and described (Swatloski, et al., 2006). Many applications can be envisioned using this material, from safety paper to medicinal applications.
Figure 3.
Their Toxicological Profile
Toxicological Screening and Comparison of IL Toxicity. We have conducted toxicity screening of 1-butyl-3methylimidazolium chloride using nematodes with Professors Guy and Kim Caldwell of the University of Alabama Department of Biological Sciences (Swatloski, et al., 2004). We established the use of Caenorhabditis elegans as a model organism for inexpensively and quickly exploring toxicological effects of 1-alkyl-3-methylimidazolium chloride ILs. C. elegans exposed to 1-butyl-3-methylimidazolium chloride at any of the concentrations tested (1.0–5.0 mg/mL) did not display adverse effects and remained viable (Figure 4A). However, 1-methyl-3-tetradecylimidazolium chloride was lethal to C. elegans at all concentrations tested (Figure 4B).
Figure 4.
Their Use in Chemical Transformations
Screening of Solvent Properties and Catalytic Activity. Several ILs were used as solvents in the reaction between methyliodide and Vaska’s complex (P’Pool, et al., 2005). Their behavior in this reaction is different from classical organic solvents such as DMF. It is concluded that, compared to molecular solvents, the use of IL solvents establishes a completely different reaction mechanism. While the reaction constant here was found to be 5–10 times lower than in organic solvents, other reactions can proceed much faster in IL solvents (Sliger et al., 2005). Consequently, it was shown that certain ILs may promote a reaction like the hydroesterification of styrene and derivatives, while other ILs completely inhibit the same reaction (Klingshirn, et al., 2005b).
Their Tunable Nature
New kinds of ions have been developed and their synthesis described (Fox, et al., 2005). It is expected that comparison between the new structures and their isolobal known ion structures will reveal new insights in the structure-property relationship of ILs. New combinations of well-known ions were investigated as biologically active compounds for disinfection and wood preservation (Pernak, et al., 2006).
Computational studies were carried out.
The hydrogen bond donor/acceptor behavior of a wide range of halogenated molecules was assessed by the Quantitative Structure-Activity Relationship/Quantitative Structure-Property Relationship (QSAR/QSPR) (Oliferenko, et al., 2004).
Conclusions:The versatility of ILs in crystallization processes, as well as their advantageous use as solvents or catalysts, have been demonstrated. Our knowledge about ILs has been deepened on a broad base; for example, the understanding of the anion’s role in the dissolution of cellulose and preparation and characterization of many useful composite materials. Important data on the field of toxicity have been generated, and known ions in new combinations showed promising results in disinfection and preservation applications. New processes that convert biomass, like cellulose, into textiles or chemical intermediates and commodities can be envisioned by making use of the technologies investigated. New crystals with new properties will be designed, and new applications as well as a new understanding of ILs themselves will certainly be a consequence of the research performed by the financial aid of this grant. Therefore, we conclude that ILs represent a technological approach that can potentially help solve many problems related to industrial chemical transformations, as well as to everyday life. The research presented in the publications and presentations below is the new knowledge gained in this field.
References:
Klingshirn MA, Spear SK, Holbrey JD, Rogers RD. Ionic liquids as solvent and solvent additives for the synthesis of sol–gel materials. Journal of Materials Chemistry 2005a;15:5174-5180.
Klingshirn MA, Rogers RD, Shaughnessy KH. Palladium-catalyzed hydroesterification of styrene derivatives in the presence of ionic liquids. Journal of Organometallic Chemistry 2005b;690(15):3620-3626.
Journal Articles on this Report: 18 Displayed | Download in RIS Format
| Other project views: | All 108 publications | 22 publications in selected types | All 18 journal articles |
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Fox PA, Griffin ST, Reichert WM, Salter EA, Smith AB, Tickell MD, Wicker BF, Cioffi EA, Davis JH, Rogers RD, Wierzbicki A. Exploiting isolobal relationships to create new ionic liquids: novel room-temperature ionic liquids based upon (N-alkylimidazole)(amine)BH2+ “boronium” ions. Chemical Communications 2005;(29):3679-3681. |
R831432 (2005) R831432 (Final) |
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Holbrey JD, Reichert WM, Rogers RD. Crystal structures of imidazolium bis(trifluoromethanesulfonyl)-imide ‘ionic liquid’ salts: the first organic salt with a cis-TFSI anion conformation. Dalton Transactions 2004;(15):2267-2271. |
R831432 (2004) R831432 (Final) |
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Holbrey JD, Vigour KB, Reichert WM, Rogers RD. The structure of [Co(H-tptz)Cl3]·H2O (tptz=2,4,6-tri(2-pyridyl)-1,3,5-triazine) prepared by crystallization from the ionic liquid, N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide. Journal of Chemical Crystallography 2006;36(12):799-804. |
R831432 (Final) |
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Klingshirn MA, Spear SK, Subramanian R, Holbrey JD, Huddleston JG, Rogers RD. Gelation of ionic liquids using a cross-linked poly(ethylene glycol) gel matrix. Chemistry of Materials 2004;16(16):3091-3097. |
R831432 (2004) R831432 (Final) |
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Klingshirn MA, Spear SK, Holbrey JD, Rogers RD. Ionic liquids as solvent and solvent additives for the synthesis of sol–gel materials. Journal of Materials Chemistry 2005;15:5174-5180. |
R831432 (2005) R831432 (Final) |
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Klingshirn MA, Rogers RD, Shaughnessy KH. Palladium-catalyzed hydroesterification of styrene derivatives in the presence of ionic liquids. Journal of Organometallic Chemistry 2005;690(15):3620-3626. |
R831432 (2005) R831432 (Final) |
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Moulthrop JS, Swatloski RP, Moyna G, Rogers RD. High-resolution 13C NMR studies of cellulose and cellulose oligomers in ionic liquid solutions. Chemical Communications 2005;(12):1557-1559. |
R831432 (2005) R831432 (Final) |
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Oliferenko AA, Oliferenko PV, Huddleston JG, Rogers RD, Palyulin VA, Zefirov NS, Katritzky AR. Theoretical scales of hydrogen bond acidity and basicity for application in QSAR/QSPR studies and drug design. Partitioning of aliphatic compounds. Journal of Chemical Information and Computer Sciences 2004;44(3):1042-1055. |
R831432 (Final) |
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P’Pool SJ, Klingshirn MA, Rogers RD, Shaughnessy KH. Kinetic study of the oxidative addition of methyl iodide to Vaska's complex in ionic liquids. Journal of Organometallic Chemistry 2005;690(15):3522-3528. |
R831432 (2005) R831432 (Final) |
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Pernak J, Smiglak M, Griffin ST, Hough WL, Wilson TB, Pernak A, Zabielska-Matejuk J, Fojutowski A, Kita K, Rogers RD. Long alkyl chain quaternary ammonium-based ionic liquids and potential applications. Green Chemistry 2006;8:798-806. |
R831432 (Final) |
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Pusey ML, Paley MS, Turner MB, Rogers RD. Protein crystallization using room temperature ionic liquids. Crystal Growth & Design 2007;7(4):787-793. |
R831432 (Final) |
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Reichert WM, Holbrey JD, Vigour KB, Morgan TD, Broker GA, Rogers RD. Approaches to crystallization from ionic liquids: complex solvents-complex results, or, a strategy for controlled formation of new supramolecular architectures? Chemical Communications 2006;(46):4767-4779. |
R831432 (Final) |
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Remsing RC, Swatloski RP, Rogers RD, Moyna G. Mechanism of cellulose dissolution in the ionic liquid 1-n-butyl-3-methylimidazolium chloride: a 13C and 35/37Cl NMR relaxation study on model systems. Chemical Communications 2006;(12):1271-1273. |
R831432 (Final) |
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Sliger MD, P’Pool SJ, Traylor RK, McNeill III J, Young SH, Hoffman NW, Klingshirn MA, Rogers RD, Shaughnessy KH. Promoting effect of ionic liquids on ligand substitution reactions. Journal of Organometallic Chemistry 2005;690(15):3540-3545. |
R831432 (2005) R831432 (Final) |
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Swatloski RP, Holbrey JD, Memon SB, Caldwell GA, Caldwell KA, Rogers RD. Using Caenorhabditis elegans to probe toxicity of 1-alkyl-3-methylimidazolium chloride based ionic liquids. Chemical Communications 2004;(6):668-669. |
R831432 (2004) R831432 (Final) |
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Swatloski RP, Holbrey JD, Weston JL, Rogers RD. Preparation of magnetic cellulose composites using ionic liquids. Chimica Oggi/Chemistry Today 2006;24:(2). |
R831432 (Final) |
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Turner MB, Spear SK, Holbrey JD, Rogers RD. Production of bioactive cellulose films reconstituted from ionic liquids. Biomacromolecules 2004;5(4):1379-1384. |
R831432 (2004) R831432 (Final) |
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Turner MB, Spear SK, Holbrey JD, Daly DT, Rogers RD. Ionic liquid-reconstituted cellulose composites as solid support matrices for biocatalyst immobilization. Biomacromolecules 2005;6(5):2497-2502. |
R831432 (2005) R831432 (Final) |
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room temperature ionic liquids, imidazolium salts, separation science, partitioning, VOC, pollution prevention, alternative solvents,
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INTERNATIONAL COOPERATION, Sustainable Industry/Business, Scientific Discipline, RFA, POLLUTION PREVENTION, Technology for Sustainable Environment, Sustainable Environment, waste reduction, Chemicals Management, Environmental Engineering, cleaner production/pollution prevention, Environmental Chemistry, clean technology, cleaner production, toxicity, green chemistry, solvents, pollution prevention for industrial residuals, solvent substitutes, benchmark performance, green process systems, environmentally benign solvents, industrial innovations, industrial process, source reduction, innovative technology, ionic liquids, linear solvent free energy relationships
Relevant Websites:
http://bama.ua.edu/~rdrogers
http://bama.ua.edu/~cgm
Progress and Final Reports:
2004 Progress Report
2005 Progress Report
Original Abstract