Comments on: Ionic Liquids Lose their Green Stripes

By: David Bradley

David Bradley — Wed, 05 Sep 2007 20:52:15 +0000

The Nature paper cited in the C&EN report on distillable ionic liquids has turned out to be rather popular topping citation index analysis in chemistry recently.

‘The distillation and volatility of ionic liquids’ was first published in the renowned science journal Nature in 2006 by scientists from QUILL (Queen’s University’s Ionic Liquids Laboratories) , who were awarded the Queen’s Anniversary Prize in February 2006.

With a huge rise in scientific interest in room temperature ionic liquids – salts that are liquid below 100°C – in recent years, the ground-breaking paper blew apart a major myth.

It illustrated that these liquids, previously regarded as involatile, are in fact volatile. The paper also demonstrated that the liquid salts can be vaporised with no decomposition and recovered and purified by fractional distillation.

By: sciencebase

sciencebase — Wed, 17 May 2006 14:59:39 +0000

Indeed, there are always two sides to every story and I’ve certainly been impressed with the various efforts to find alternatives to volatile organic compounds (VOCs), viz supercritical fluids (SCFs) and room temperature ionic liquids (RTILs). One also has to consider the energy, environmental and economic costs of refitting a global industry to be able to handle these new solvents too. It isn’t after all simply a case of swapping out the toluene and using an RTIL instead.

Additionally, the long-term impact of RTILs on the environment is not known, what if they turn out to be worse than VOCs for some as yet unknown reason. A comment on another post on the site also asked, what should we do with an RTIL once we’re finished using it for a particular reaction, bury it?

By: Castor Oil

Castor Oil — Wed, 17 May 2006 14:45:11 +0000

While it is possible that ionic liquids are not as “green” as previously thought, another way of looking at it could be on a relative scale instead of on an absolute scale. On an absolute scale, perhaps yes, they are not absolutely “green”. But I’d imagine that they are still much more green that their volatile, toxic, organic counterparts?

Another way of looking at this could be: what are the alternatives to ionic liquids? Are there better alternatives from whom the cost to ecology/environment is less than that for ionic liquids?

Just some thoughts

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