Frontier Leaders: In Search of an Ionic Liquid Effect

Frontier Leaders of Today
for the Scientists of Tomorrow

ITQB PhD Program Seminar Series

Title: In Search of an Ionic Liquid Effect

Speaker: Thomas Welton

Affiliation: Imperial College, UK

More Information: Poster

Abstract

Since the introduction of air and water stable salts that are liquid at room temperature, there has been an explosion of interest in the application of these as solvents for chemicals synthesis and processing. Much of this interest has been centred on the possibility that the ionic media provided by these solvents might offer process advantages over molecular solvents or perhaps novel behaviours that cannot be achieved with molecular solvents.

The phrase “ionic liquid effect” has been used many times in the literature. However, if the definition used for “ionic liquid effect” is that it is a phenomenon that is qualitatively different in ionic liquids that arises because the liquid is composed of ions and is observed in all ionic liquids and not observed in any molecular nor solid system, then we are unable to find an example that has been demonstrated to meet this. In spite of efforts to detect such effects our detailed quantitative investigations on the effects of ionic liquids on reactions of solutes have repeatedly demonstrated that results can be correlated with, and hence rationalized in terms of, polarity behaviours originally derived to describe molecular solvents.

However, we have now reported that the SN2 reaction of the trifluoromethanesulfonate and bis(trifluoromethanesulfonyl)imide salts of dimethyl-4-nitrophenylsulfonium ([p-NO2PhS(CH3)2][X]; [X]- = [CF3SO3]-, [N(CF3SO2)2]-) with chloride ion follow a fundamentally different pathway to when the same salts react in any molecular solvent.

Our results show that these reactions occur without the initial formation of ion pairs that is seen in molecular solvents, in spite of the considerable ion association that is present in the system.

In this presentation, I compare this reaction to other nucleophilic substitution reactions in ionic liquids as a means of exploring solvent solute interactions in ionic liquids.

Short CV

Prof Thomas Welton, FRSC
Professor of Sustainable Chemistry, Head of Department.
Department of Chemistry, Imperial College, London, UK

Previous Employment
2004-2007 Imperial College, Professor in Sustainable Chemistry, Director of Undergraduate Studies (Chemistry).
2002-2004 Imperial College, Reader in Catalysis, Director of Undergraduate Studies (Chemistry).
2000-2002 Imperial College, Senior Lecturer in Inorganic Chemistry.
1995-2000, Imperial College, Lecturer in Inorganic Chemistry.
1993-1995, Imperial College, Lloyds of London Tercentenary Fellow.
1991-1993, University of Exeter, Demonstrator in Inorganic Chemistry.
1988-1991, University of Sussex, Post-doctoral Research Fellow.

Awards and Honours
2007, RSC Sir Christopher Ingold Lectureship
2007,  Fellow of the Royal Society of Chemistry
2001, New Voice in Chemistry, ACS.
1993, Lloyds of London Tercentenary Fellowship

Editorships
2005-date  Green Chemistry, Scientific Editor, RSC,

Qualifications
1990, D.Phil., University of Sussex, Chemistry and Spectroscopy of Ionic Liquids,
1985, B.Sc. (Hons) 2(i), University of Sussex, Chemistry,

Research Interests
Sustainable or Green Chemistry aims to make the chemicals, and related, industries both environmentally and economically sustainable. It encompasses a range of activities, such as making biodegradable products, sourcing chemicals from renewable resources and/or making chemicals processes more efficient in energy and less wasteful in materials.
I am interested in using solvents to improve chemical processes. I have worked with ionic liquids throughout my research career. Recently, interest from both academic and commercial chemists in these has increased dramatically. My work has made a significant contribution to this change in attitude. I also work with other solvents, e.g. siloxanes, PEG's and solvents from renewable resources, all with a view to the development of sustainable solvent technologies. My research covers a broad range of the chemical sciences and I have been the author of papers in all three of the traditional branches of the subject (Inorganic, Organic and Physical). I am particularly interested in clean synthesis and catalysis.
The central academic aim of my research is to understand the role that the immediate chemical environments in which reacting species find themselves influence the reaction process. I also aim to use this understanding to provide more effective chemical processes by the matching of the reaction with the optimum reaction environment. The principal foci of my investigations are the reactions themselves and how they change in rate, product distributions etc.. My group correlate our synthetic results with calculated values (e.g. gas phase acidities) and physical measurements (e.g. the spectra of probe dye molecules).

Publications
I am the author of over 90 full papers, primarily on the structures and chemistry of ionic liquids and solutes in these. I have published in high impact international research journals in Physical, Inorganic, and Organic Chemistry and Chemical Engineering. These have been cited over 8,000 times, and have an H-index of 31.

Research Group
I have graduated 14 PhD students to date and supervised 8 post-doctoral researchers and numerous Masters students.