We started publishing in the ionic liquids field at an interesting time. The idea of using "Ionic Liquids" (ILs) or "Molten Salts" for chemistry was not new; a lot of really good work preceded the time of our entry, but there was a change in the way people were thinking of the use of ILs. Early on, the concept of using these liquid salts as bulk solvents sparked the imagination and we started trying to make connections between the generic use of solvents in industrial application and the chemical and physical properties of the ILs.

I believe that one of our early communications got just enough attention to point out the application of ILs to liquid/liquid separation. The point is not that the idea was necessarily new, but it was emphasizing that here is a bulk application of solvents for which you should consider using a nonvolatile liquid salt.

The generation of new ideas around this theme led to additional interest and the work was cited.

Similarly, we measured and published physical property data which was an attempt again to bring some of this data to light. The idea was to give people enough data to start evaluating the use of ILs in other processes. A lot of great people are now measuring physical properties, cataloging them, and even creating databases. This is essential for the field.

Our work is thus most likely highly cited because it was published early with the idea that people would use the data to make further improvements and generate new applications.

During the 1980s as a faculty member at Northern Illinois University, I was working on eliminating volatile organic solvents in liquid/liquid separations by utilizing aqueous biphasic systems. When certain water soluble, nontoxic polymers like polyethylene glycol (PEG) are "salted-out" one generates two immiscible phases, which are both are over 80% water on a molar basis.

Even before "Green Chemistry" was as widespread as it is now, it was obvious that more environmentally benign chemistry was needed, and certainly "volatile organic compounds" (VOCs) had achieved a very negative connotation in the general public.

Our work with ILs arose from trying to develop non-VOC liquid/liquid separations and a chance encounter with Professor Ken Seddon. I met Ken at a Crystal Engineering Conference in Digby, Nova Scotia, where we discussed whether there were any hydrophobic ionic liquids that would be immiscible with water (and thus form two phase systems for separations). I wanted to do separations from water and ILs sounded like another alternative to VOCs which would compliment our work with PEG aqueous biphasic systems.

The role of our literature in the field has been to help increase the awareness of the IL field, what ILs can do, but also what they cannot do. We have tried to connect an underlying molecular-level understanding between several apparently disparate areas which turn out to be similar. In the process, we have attempted to generate ideas for new applications of ILs beyond their use in organic synthesis. I would really like to see us truly take advantage of the unique chemistries ILs have to offer, and use them for what they can do rather than just for what we want them to do.

There has been, of course, an explosion of interest—both academic and industrial—in the field. We have seen a wide variety of R&D personnel with a truly interdisciplinary range of expertise join the fray. This is exactly what the field needed.

Now we are seeing major suppliers (e.g., Merck/EMD, Solvent Innovations, BASF, SACHEM, etc.) with in-house R&D, scale-up, and business expertise. New technologies are being developed and patented at an increasing rate. The price of ILs is decreasing and availability is increasing. Academics are generating know-how with technology and students which is being transferred to industry.

Despite the advances, we do sometimes see too much reliance on older literature. The know-how in the field is still improving. Referees sometimes attack papers for issues which have no bearing on the application, but rather because of what they have heard is a problem for "ionic liquids." Scientists start using an IL they have read about in the literature instead of choosing one specifically for the chemistry they wish to do.

We are just now getting to the point where many researchers consider the range of ILs and the fact that there are no "generic" properties for a class of fluids which may have billions of examples!

As the IL field matures we will see unique innovative chemistry based on specific families of ILs that deliver a very specific advantage. We will see a decline in the "me-too" chemistry in which everything is tried in an IL regardless of whether it makes sense to use an IL for that application.

The field will move beyond "demonstration of concept" to utilization of ionic liquids in industrial process and technology transfer. This isn’t hard for me to say since it’s already happening!

The field is and will continue to define the unique opportunities presented by ILs by understanding the fundamental nature of liquid salts and what they can and cannot do.

ILs will be part of a tool box. Potential applications will be researched, and development work will follow to demonstrate the feasibility of new technologies to specific industries.

This is really not restricted to the IL work. Be curious. Reject the "been there/done that" attitude you often face. Be confident enough to follow your own ideas to completion. And, of course, dream big.

Robin D. Rogers, Ph.D.
University of Alabama
Tuscaloosa, AL, USA