Another claimed virtue of DESs is their reusability. In order to test
thewaste glycerol DESs, we reused the same DES for five successive esterifications
of palmitic acid (as described above). On each of the five
days, we observed complete conversion to the ester product. Additionally,
it is important to determine if the DESs is changing composition
during the course of the reaction. This would indicate that the DES is
participating in the reaction instead of merely serving as the solvent.
However, 1H NMR analysis of the DES before and after the five day experiment
showed no change in composition of the DESs. Thus, the DES
prepared with waste glycerol serves as a reusable solvent system.