Efficient catalysis for the Baeyer-Villiger oxidation reaction of 2-adamantone in acidic deep eutectic solvents

A deep eutectic solvent (DES) comprising p-toluenesulfonic acid (PTSA) and polyethylene glycol 200 (PEG200) was synthesized and applied to the Baeyer-Villiger (B-V) oxidation reaction of 2-adamantanone, which exhibited good catalytic effect and cyclic stability under relatively mild conditions. It was found that the hydrogen bond of DESs not only governed their physical properties, such as viscosity and electrical conductivity, but also influenced their chemical behavior, including the catalytic effect in B-V oxidation reaction. By adjusting the composition, the hydrogen bond properties can be optimized. This study aims to elucidate the intricate relationship between composition, hydrogen bond strength, and physicochemical properties of DESs, thereby establishing a preliminary theoretical foundation for a comprehensive understanding and construction of DESs systems. This provides a novel and promising environmentally friendly approach for the B-V oxidation reaction.