Quantitative Control Factors of Double Salt Ionic Liquids Catalysis in the Coupling Reaction of Epoxied and Methanol

In recent years, multi-ionic liquids (ILs) mixture systems have been widely noticed and applied in catalysis due to their unique properties. In order to establish the quantitative relationship between parameters and catalytic behavior, double salt ILs (DSILs), with different cation (1-ethyl-3-methylimidazolium, choline, tetraethylammonium) but same anion (acetate), are performed in the coupling reaction of propylene oxide (PO) with methanol. In the present work, the DSILs properties like Hammett basicity (H0), hydrogen bond donor (HBD) ability (α), hydrogen bond acceptor (HBA) ability (β) and dipolarity/polarizability effect (π*) were considered in the reaction. These control factors were quantitative related to catalytic performance by a modified liner solvent energy relationship (LSER) function that adding a Hammett function correction term. According to the modified-LSER, solvents with different parameters were tested to verify its validity and control the reaction. This study demonstrated each parameter could make a different contribution to chemical reaction. It provides a new perspective way for multi-ILs mixture avoiding the intricacies of the parameter relation in ILs catalysis reasonably.