Oxidation of Cyclohexene to trans-1,2-Cyclohexanediol Promoted by p-Toluenesulfonic Acid without Organic Solvents

This experiment describes a method for cyclohexene oxidation to trans-1,2-cyclohexanediol using p-toluenesulfonic acid (p-TsOH) as promoter and hydrogen peroxide as oxidant in a biphasic system. This method allows conversions up to 97.9% (monitored by (1)H NMR). trans-1,2-Cyclohexanediol was not easily separated from the aqueous solution owing to formation of an azeotropic mixture with water. Destruction of the azeotropic mixture was observed in the presence of sodium p-toluenesulfonate salt (p-TsONa). Therefore, water could be removed by simple distillation after p-TsOH neutralization. Purification of trans-1,2-cyclohexanediol was accomplished by sublimation. The overall reaction, separation, and purification experiment did not require any organic solvent.