An ionic liquid that could be used to control pH in chemical reactions has been developed by scientists in China.

You-zhu Yuan at Xiamen University and co-workers reacted the basic part of the class of ionic liquids known as imidazolium hydroxides, with acids such as phthalic acid or tartaric acid. The researchers found that a new type of ionic liquid formed, which acts as a pH buffer in non-aqueous environments. The acid and base components of the ionic liquid remain in a 1:1 ratio. 

Controlling pH is important for many chemical reactions, as fluctuations can affect the outcome. There are several ways to control pH in reactions in water soluble liquids, but fewer for reactions that work in non water soluble liquids, such as organic solvents and ionic liquids, according to Yuan. The rate of hydrogenation of olefins, a reaction catalysed by ruthenium in an ionic liquid, is drastically affected by pH, as Yuan's team have demonstrated.

'Non-aqueous systems with tailored ionic liquid buffers offer new possibilities for the biotechnological production of many useful chemicals that are not soluble in aqueous media,' said Yuan. 

Peter Halling is an expert in biocatalysis in non-aqueous media at the University of Strathclyde, Glasgow, UK. He believes the effect of acid-base conditions in ionic liquids hasn't received the attention it deserves, especially since ionic liquids are often used as the medium for enzymatic reactions. 'This work should form the basis for better understanding and optimization of acid-base conditions in these reaction media, which are of much current interest,' said Halling. 

Katherine Vickers