An oxalate-based DES with a tetrabutyl ammonium chloride and oxalate acid molar ratio of 1/2 (TBO1 : 2) exhibited high activity in oxidative desulfurization (ODS) of dibenzothiophene (DBT) under mild reaction conditions.

The use of coupled catalytic systems with ETMs facilitates the reaction process by transporting electrons from catalysts to the oxidant along a low-energy pathway and, finally, DBT was prone to oxidize to DBTO₂.

Choline chloride-based deep eutectic solvents (DESs) exhibited remarkable activity in the cycloaddition of CO₂ with propylene oxide (PO) in the absence of any additives under solvent- and metal-free conditions as well as recyclability.