Green Chemistry Blog

Ionic liquids have been touted as green solvents since even before the definition of green chemistry was presented in Anastas and Warner’s seminal text. Academic research on ionic liquids, across many varied applications, is a strong and still growing area of interest. Despite this, the commercialisation of ionic liquid products, and their utilisation as solvents in manufacturing processes, has been limited because of their high costs.

In this latest work from Jason Hallett and colleagues from Imperial College London, the economic feasibility of two ionic liquids synthesized by acid–base neutralization has been assessed. It was found that process intensification dramatically reduces the end cost of these ionic liquids, and is recommended in this latest work as a means of reducing the cost of ionic liquids so that their potential in commercial applications may be realised.

The prices of triethylammonium hydrogen sulfate and 1-methylimidazolium hydrogen sulfate produced with optimised manufacturing methods are estimated to be as little as $1.24 kg⁻¹ and $2.96 kg⁻¹ respectively, which are largely dictated by the raw material costs. These prices are similar to conventional organic solvents such as acetone, while at present typical ionic liquid prices can be two orders of magnitude greater than this. The authors conclude that  more effort should be dedicated to developing new ionic liquids that can be synthesised from affordable raw materials in very few steps.

http://pubs.rsc.org/en/content/articlelanding/2014/gc/c4gc00016a#!divAbstract