The Baeyer–Villiger oxidation of ketones with Oxone® in the presence of ionic liquids as solvents

Cyclic and linear ketones were readily oxidised with Oxone® at 40 °C in ionic liquids as solvents and short times (2.5–20 h), affording their corresponding lactones and esters in high yields (65–95%). Both, aprotic and protic ionic liquids were used. The best conversion of ketones and the highest yields of products were obtained with 1-buty-3-methylimidazolium tetrafluoroborate and 1-methylimidazolium acetate as solvents. These ionic liquids were also efficiently recycled in the Baeyer–Villiger reaction without significant loss of activity. Several factors, such as the partial solubility of KHSO5 in the ionic liquid, its viscosity and the presence of a proton in protic ionic liquids, have an influence on the course of the reaction.