A quick, simple, robust method to measure the acidity of ionic liquids.

Introduced here is a quick, simple, robust method to measure acidity in ionic liquid (IL) systems by the use of the NMR-probe mesityl oxide. Acidity corresponding to a Hammett acidity of - 1 to - 9 can be measured reliably using this technique, a range that vastly exceeds that of any single UV-vis probe. [ABSTRACT FROM AUTHOR]