Determination of the Lewis acidity of amide-AlCl3 based ionic liquid analogues by combined: In situ IR titration and NMR methods

Abstract

A combinatorial method to determine both acidic strength and acidic amount of each Lewis acid site in amide-AlCl3 based ionic liquid (IL) analogues was developed by the combination of in situ IR titration and NMR analysis. 31P NMR was used to distinguish effectively the acidic strength of each Lewis acid site in the amide-AlCl3 based IL analogues. Nitrobenzene was used as a molecular probe to measure the total Lewis acidic amount of the amide-AlCl3 based IL analogues by in situ IR titration. The acidic amount of each Lewis acid site in the amide-AlCl3 based IL analogues was calculated with the assistance of 27Al NMR analysis.