Innovations in Industrial and Engineering Chemistry - ACS Publications

Chapter 11

Ionic Liquids: Growth of a Field through the Eyes of the I&EC Division 1

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Downloaded by PENNSYLVANIA STATE UNIV on July 1, 2012 | http://pubs.acs.org Publication Date: December 31, 2008 | doi: 10.1021/bk-2009-1000.ch011

Héctor Rodríguez , Gabriela Gurau , and Robin D. Rogers * 1

The Quill Research Centre and School of Chemistry and Chemical Engineering, The Queen's University of Belfast, Belfast, Northern Ireland BT9 5AG, United Kingdom Center for Green Manufacturing and Department of Chemistry, The University of Alabama, Tuscaloosa, A L 35401 2

The last decade has witnessed an indisputable burgeoning of research within the field of ionic liquids, both in academe and industry. Part of the responsibility for this explosion of interest can be attributed to the strong commitment of the American Chemical Society's Industrial and Engineering Chemistry Division and its subdivisions. In particular, the oral and written forums sponsored by the Division have enhanced discourse between scientific and industrial partners across the world and have served as a platform for advances in the field. Here, through a series of snapshots represented by the Division's five major ionic liquids symposia, we take a look at the world of ionic liquids.

© 2009 American Chemical Society

In Innovations in Industrial and Engineering Chemistry; Flank, W., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2008.

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Introduction One of us (RDR) was introduced to the I&EC Division through its Separation Science & Technology Subdivision, where service on the Program Committee began in 1992. The SS&T Subdivision and the I&EC Division had a history of allowing diverse programming and providing a forum for both fundamental and applied research. RDR co-organized his first symposium in the Division in 1994 ("Aqueous Biphasic Separations: Biomolecules to Metal Ions," with C. K . Hall) for the 207 A C S National Meeting in San Diego, C A and went on to co-organize seven other symposia through the year 2000 on a variety of topics in separations science. In 1996, coinciding with his move back to The University of Alabama, R D R attended a N A T O Advanced Study Institute meeting on crystal engineering in Digby, Nova Scotia, Canada (7) where he met one of the co-organizers of that meeting, Prof. Kenneth R. Seddon, from The Queen's University of Belfast. That meeting led to discussions on whether pure salts could be used as solvents for separations and green chemistry (2). A research program, a friendship, and a long term collaborative commitment to a field were born. Here we follow one aspect of that collaboration: commitment to facilitating communication for all practitioners in the field.


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Ionic Liquids: Onto the Big Stage and Into I&EC Ionic compounds which are liquid at room temperature have been around for quite a long time (3). The first room temperature ionic liquid dates back from as early as 1914, when ethylammonium nitrate was originally reported (4). More recently in the US, important work in the area of electrochemistry has been carried out with low melting chloroaluminate salts over at least the last thirty years or so (5). However, worldwide attention to the concepts of 'ionic liquids' became focused in the very last years of the 20 century, when a series of publications raised interest in ionic liquids as alternative 'green' solvents (2,610). The unique properties and promising applications of these "liquid salts" attracted an increasing number of research groups, coming from increasingly varied scientific backgrounds. The evidence for an inflexion point in the history of ionic liquids in the late 1990s, can be clearly observed in Figure 1, where the number of publications in the literature involving this family of compounds (as retrieved by Web of Science® of the ISI Web of Knowledge ) is plotted as a function of time. In understanding this impressive growth, it is also noteworthy to indicate that in 1999 The Queen's University Ionic Liquids Laboratory (QUILL), the first center entirely devoted to research within ionic liquids, was founded with 16 industrial members. th

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Figure 1. Number of publications per year (black bar) and cumulative number of publications (grey bar) in the period 1988-2007 containing the phrase "ionic liquid(s) " in the title, abstract, or keywords, as reported by Web of Science® of the ISI Web ofKnowledge SM

In April 2000, the first international meeting devoted to ionic liquids was held in Heraklion, Crete, Greece. This N A T O Advanced Research Workshop on Green Industrial Applications of Ionic Liquids (11,12), was a closed five-day workshop intended to increase awareness of ionic liquids, bring new research expertise into the field, and set a research agenda for its future. The organizers (Profs. R. D . Rogers, K . R. Seddon, and S. Volkov) struggled at the time to get 50 international scientists working in the field interested in attending the meeting. Among the ten major outcomes of this meeting, the two most cited are (12): •

•

"Ionic liquids are intrinsically interesting and worthy of study for advancing science (ionic vs. molecular solvents) with the expectation that something useful may be derived from their study." "Combined with green chemistry, a new paradigm in thinking about synthesis in general, ionic liquids provide an opportunity for science/engineering/business to work together from the beginning of the field's development."

But two of the other outcomes deserve mention here: •

"There is an urgent need to increase the number, but especially the areas of


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expertise, of ionic liquids researchers. A model of open collaboration needs to be encouraged." "International collaboration, communication, and education regarding the results are needed."

These latter two outcomes pointed to the urgent need to bring people of varied backgrounds and interest together and to disseminate information. For Profs. Rogers and Seddon, this meant I&EC, and the following year they took this concept to the Program Committee. In April 2001, one year after the N A T O meeting in Crete, I&EC held its first ionic liquids symposium "Green (or Greener) Industrial Applications of Ionic Liquids" at the A C S national meeting held in San Diego, C A . Over 350 attended the opening session of this 5-day symposium; the majority from industry. In the following sections we will overview the evolution of the ionic liquids field through the analysis of the content of these meetings.

Evolution of Ionic Liquids through the Eyes of I&EC The Meetings The first of the symposia (Table I) on ionic liquids sponsored by I&EC was also the first open international meeting on the fundamentals and applications of ionic liquids period. "Green (or Greener) Industrial Applications of Ionic Liquids" (75) brought together the key players in this burgeoning area in a forum for the exchange of ideas between academe and industry. The high attendance, vigorous discussions, and successful proceedings publication, indicated that these meetings should be continued. The second symposium, "Ionic Liquids as Green Solvents: Progress and Prospects" (14), was held in Boston, M A in August 2002, in the framework of the 224 A C S National Meeting. Coming as it did, only 18 months after the San Diego meeting, the varied presentations and high attendance gave notice of a rapidly evolving field. Indeed, "Progress" was rapid and the "Prospects" were good. Based on general prompting by the community, a third meeting was set for the following year to complete the trilogy! New York, N Y hosted the 226 A C S National Meeting in September 2003, and I&EC's "Ionic Liquids: Fundamentals, Progress, Challenges, and Opportunities" (15,16). Despite the short period of time elapsed from the previous symposium (12 months), the frenetic pace of the field was evident during the sessions. A broad and diverse base for activities could be identified, as well as the excitement of even newer potential opportunities for the field. th

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393 Table I. I&EC ionic liquids symposia. (See page 2 of color insert.) I&EC Symposium

Topics Covered


Green (or Greener) Industrial Applications of Ionic Liquids

(13)

April 1-5, 2001 San Diego, C A 221 A C S National Meeting http://bama.ua.edu/~rdrogers/sandiego (last accessed March 29, 2008) st

Ionic Liquids as Green Solvents: Progress and Prospects

(14)

August 18-22, 2002 Boston, M A 224 A C S National Meeting http://bama.ua.edu/~rdrogers/Boston (last accessed March 29, 2008) th

• • • • • • • • • •

Ionic Liquids in Context Separations and Engineering Green Synthesis Nuclear and Electrochemistry Ionic Liquid Systems Properties of Ionic Liquids Catalysis I Catalysis II Structure and Photochemistry High-Temperature and Other Systems

• Ionic Liquid Tutorial • Manufacture and Synthesis of Ionic Liquids: Industrial and Academic • Characterization and Engineering • Novel Applications of Ionic Liquids • Separations • Biotechnology • Catalytic Chemistry • Non-Catalytic Chemistry • Electrochemistry • Photochemistry and Reaction Intermediates

Continued on next page.


394 Table I. Continued. (See page 3 of color insert.) Topics Covered

I&EC Symposium


Ionic Liquids III: Fundamentals, Progress, Challenges, and Opportunities

(15,16)

September 7-11,2003 New York, N Y 226 A C S National Meeting

• Ionic Liquid Tutorials • Fuels and Applications • Physical and Thermodynamic Properties • Catalysis and Synthesis • Spectroscopy • Separations • Novel Applications • Catalytic Polymers and Gels • Electrochemistry • Inorganic and Materials • General Contributions

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http://bama.ua.edu/~rdrogers/New York

(last accessed March 29, 2008)

Ionic Liquids: Not Just Solvents Anymore OR Ionic Liquids: Parallel Futures

(17)

March 26-30, 2006 Atlanta, G A 231 A C S National Meeting http://bama.ua.edu/~rdrogers/Atlanta2006 (last accessed March 29, 2008) st

• Why Are Ionic Liquids Liquid? • Structure-Activity Relationships/Modeling • Environmental Fate and Toxicity • New Industrial Applications of Ionic Liquids • Really New Ionic Liquids • Ionic Liquids and Education • Applications Based on Physical Properties • Functional Ionic Liquids/Ionic Materials • Analytical Applications of Ionic Liquids • Microengineering with Ionic Liquids


395 Table L Continued, I & E C Symposium


Ionic Liqu ids: From Kncmledge to Application

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Au gust 17-21,20 08 Ρ hiladelphia, Vi\ 236 A CS National Νleeting http://bama.ua. edu/~rdrogers/Pl iiladelphia2008 (last acc;essed March 29 ,2008) th

Topics Covered

• • • • • • • • • •

Gas Separations Liquid Separations Interfacial Properties Use in Sensors and Actuators Materials Synthesis in Ionic Liquids Thermophysical Properties Molecular Simulations Pharmaceutical Applications Industrial Applications General Session

New industrial applications acquired a more relevant presence in this third meeting. After the trilogy of meetings in the period 2001-2003, a break in the ionic liquid symposia at the A C S meetings was taken over the next triennium. O f course, this was not due to the research in the field slowing down, but might be better understood as a timing adjustment. The first biennial International Congress on Ionic Liquids was held in Salzburg, Austria in June 2005; attracting nearly 500 delegates from around the world. In order to avoid excessive accumulation of high level meetings on the matter, the timing of I&EC symposia on the topic was changed to accommodate the newer meetings. Thus, the fourth of the I&EC symposia was held in March 2006, at the 231 A C S National Meeting in Atlanta, G A , with the title "Ionic Liquids: Not Just Solvents Anymore OR Ionic Liquids: Parallel Futures" (17). With an ampler time perspective, it was observed that the intense interest in the field had led to an unprecedented increase in the knowledge of salts in general, with special focus on the manipulation of their physical and chemical properties. Parallel to this fundamental knowledge, a dramatic increase in the technological application of ionic liquids had also occurred. The variety and novelty of topics presented was truly amazing. st


396 At the writing of this chapter, a fifth symposium has been organized for the August 2008 236 A C S National Meeting in Philadelphia, P A ; "Ionic Liquids: From Knowledge to Application". The field shows no signs of slowing down and over 140 abstracts have been submitted for presentation at this symposium. Each of the first four symposia (and perhaps the fifth) generated an A C S Symposium Series book (Table I) with key papers and authors chosen from the meetings. By simply following the titles, it is noticeable that the emphasis on the role of ionic liquids as solvents has decreased with time. Indeed, the boom in the field was prompted by the unique environment provided by ionic liquids to act as solvents in different processes; but, with the increase in scientific knowledge in academe and in industry, the impact of ionic liquids is going well beyond the borders of solvent applications. As the subtitle of the last book reads, ionic liquids are "not just solvents anymore". This conclusion can also be reached through the analysis of the topics of the sessions at each meeting.


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The Topics The featured topics for the sessions constituting each of the symposia organized within I&EC are provided in Table I. By closely reviewing these lists, insight into the evolution of the ionic liquids field over the last several years can be obtained. A clear example of the huge speed at which the universe of ionic liquids expanded and evolved can be found in the fact that the more or less generic topics at the first symposium hardly find any correspondent session in the fourth symposium held five years later. The first three symposia in 2001, 2002, and 2003, shared a series of topics, such as separations, synthesis, electrochemistry, engineering, or catalysis. Also, the issues of characterization and physical properties were discussed in all the meetings of this symposia trilogy. There was a clear emphasis on solvent properties and solvent applications. What happened by 2006? The generic topics were indeed discussed, but were distributed into more specialized areas. Typically, these areas were closer to final applications. From this point of view, it is interesting to note that there was no "applications" session in 2001; in 2002 a single generic topic on novel applications appeared; in 2003 this session was joined by a session on fuels and applications, by 2006, three and in 2008 five different sessions focused only on applications. Certainly, this is indicative of the amazing increase in commercial applications involving ionic liquids over the last few years (5). This trend in the field is not only evident from these symposia. Figure 2 illustrates the growth in the number of patents over the past 10 years which utilize the term 'ionic liquid(s)'. There is little wonder that ionic liquids are no longer viewed as just 'green solvents', but as enabling concepts for truly transformational technologies!



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Figure 2. Number of patents per year (black bar) and cumulative number of patents (grey bar) in the period 1998-2007 containing the phrase "ionic liquid(s) ", as reported by SciFinder®.

The Sponsorship A parallel interpretation of the significance of the symposia, and subsequently of the ionic liquids field over the current decade, can be developed through an analysis of the sponsorship of these I&EC symposia. Upon review in its entirety, the sponsorship of the I&EC symposia on ionic liquids is representative of the amazing cooperation which has been key to the success of the field; including professional societies, academe, industry, and government. The US Environmental Protection Agency's Green Chemistry Program, the US Army Research Office, and the A C S Green Chemistry Institute were among the initial sponsors of these symposia. A l l of the symposia were sponsored by I&EC, and in particular by its subdivisions Green Chemistry & Engineering and Separation Science & Technology (with the Novel Chemistry with Industrial Applications subdivision joining them in 2006). Also, academic research centers co-sponsored the events including the Center for Green Manufacturing at The University of Alabama, and Q U I L L at The Queen's University of Belfast. In 2006, the Energy Center at the University of Notre Dame added its support.


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Perhaps the hallmark of these symposia, however, has been the industrial support and participation. Nine companies from different backgrounds sponsored the first symposium in April 2001. These initial sponsors included A C R O S , B P , Covalent Associates, Chevron, Dow, Ozark Fluorine Specialties, S A C H E M , Solvent Innovation, and Union Carbide. In the following years, Cytec Industries, Fluka, Merck, Strem Chemicals, BASF, and 525Solutions have also contributed.

Conclusion: A Fascinating Future Ahead The growth of the field of ionic liquids over the last decade has truly been astonishing. A simple extrapolation to the future would indicate that ionic liquids are going to continue to be important contributors to fundamental and applied science and engineering; a perfect fit for I&EC! The new paradigms being introduced with this amazing class of compounds will become founded in a firm basis of understanding and thus lead to an ever burgeoning number of new applications, both predictable and completely unexpected at the time of writing these lines (5). While the future of ionic liquids looks bright, we must not forget that a key aspect for future success will be the continuation of open and rapid intercommunication between research groups, their industrial partners, and governmental institutions. We are confident that I&EC will continue to play a major role in this, continuing to contribute for at least the next 100 years... or more!

Acknowledgments Profs. R. Rogers, K . Seddon, and more recently J. Brennecke, as overall symposia organizers, recognize that the true success of these symposia has been in large part to the efforts of the many individual session organizers who have tirelessly contributed their talents in putting together the many excellent sessions. These organizers include A . Robertson, J. Holbrey, R. Sheldon, T. Welton, M . Earle, W. Pitner, C. Gordon, J. Davis Jr., L . Rebelo, P. Wasserscheid, S. Pandey, B. Tumas, R. Mantz, P. Trulove, M . Watanabe, H . Ohno, D. MacFarlane, M . Deetlefs , E. Maginn , G. Lamberti, R. Bernot, B . Hembre, R. Singer, J. Wilkes, D. Armstrong, R. Allen, M . Costa Gomes, M . Shiflett, J. Anderson, P. Jessop, S. Baldelli, A . Podesta, G. Baker, X . Zeng, J. Anthony, A . Mudring, J. Magee, P. Ballone, P. Schwab, and M . Turner.


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Crystal Engineering: The Design and Application of Functional Solids, N A T O Science Series C: Mathematical and Physical Sciences, V o l . 539; Seddon, K . R.; Zaworotko, M . J., Eds.; Kluwer: Dordrecht, The Netherlands, 1999. Huddleston, J. G.; Willauer, H . D.; Swatloski, R. P.; Visser, A . E.; Rogers, R. D . Room temperature ionic liquids as novel media for 'clean' liquid -liquidextraction. Chem. Commun. 1998, 1765-1766. Plechkova, Ν. V . ; Seddon, K . R. Applications of ionic liquids in the chemical industry. Chem. Soc. Rev. 2008, 37, 123-150. Walden, P. Ueber die Molekulargrösse und elektrische Leitfähigkeit einiger gesehmolzenen Salze. Bull. Acad. Impér. Sci. St. Pétersbourg 1914, 8, 405422. Wilkes, J. S. A short history of ionic liquids - from molten salts to neoteric solvents. Green Chem. 2002, 4, 73-80. Seddon, K . R. Ionic Liquids for Clean Technology. J. Chem. Tech. Biotechnol. 1997, 68, 351-356. Freemantle, M . Designer solvents - Ionic liquids may boost clean technology development. Chem. Eng. News 1998, 76[30 March], 32-37. Blanchard, L . Α.; Hancu, D.; Beckman, E. J.; Brennecke, J. F. Green processing using ionic liquids and CO . Nature 1999, 399, 28-29. Holbrey, J. D.; Seddon, K . R. Ionic Liquids. Clean Prod. Proc. 1999, 1, 223-236. Welton, T. Room-Temperature Ionic Liquids. Solvents for Synthesis and Catalysis. Chem. Rev. 1999, 99, 2071-2083. Freemantle, M . Science/technology concentrates ionic liquids. Chem. Eng. News 2000, 78[15 May], 37. Green Industrial Applications of Ionic Liquids, N A T O Science Series II: Mathematics, Physics and Chemistry, V o l . 92; Rogers, R. D.; Seddon, K . R.; Volkov, S., Eds.; Kluwer: Dordrecht, The Netherlands, 2002. Ionic Liquids - Industrial Applications to Green Chemistry, A C S Symposium Series, V o l . 818; Rogers, R. D.; Seddon, K . R., Eds.; American Chemical Society: Washington, DC, 2002. Ionic Liquids as Green Solvents - Progress and Prospects, A C S Symposium Series, Vol. 856; Rogers, R. D.; Seddon, K . R., Eds.; American Chemical Society: Washington, DC, 2003. Ionic Liquids IIIA: Fundamentals, Progress, Challenges, and Opportunities - Properties and Structure, A C S Symposium Series, V o l . 901; Rogers, R. D.; Seddon, K . R., Eds.; American Chemical Society: Washington, D C , 2005. th

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16. Ionic Liquids IIIB: Fundamentals, Progress, Challenges, and Opportunities - Transformations and Processes, A C S Symposium Series, V o l . 902; Rogers, R. D.; Seddon, K . R., Eds.; American Chemical Society: Washington, DC, 2005. 17. Ionic Liquids IV - Not Just Solvents Anymore, A C S Symposium Series, Vol. 975; Brennecke, J. F.; Rogers, R. D.; Seddon, K . R., Eds.; American Chemical Society: Washington, DC, 2007.


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