Intricate kinetics: in situ FTIR-spectroscopy discloses a phase change during ionic liquid synthesis

The kinetics of the methylation of triethylamine (NEt ) with dimethyl carbonate (DMC) in methanol have been investigated by means of in situ ATR-IR-spectroscopy. The data show an autocatalytic influence of the ionic product on reaction kinetics. A bend in the reaction rate progress indicates a sudden change from solvated ions to a microstructured biphasic system, which is reflected in the dependence of the reaction rate constant on the product concentration and the Hildebrand parameter.