Liquid Phase Beckmann Rearrangement of Cyclohexanone Oxime into ε-Caprolactam Catalyzed by D-72 Sulfonic Acid Resin

The liquid phase Beckmann rearrangement of cyclohexanone oxime into e-caprolactam was successfully developed by using D-72 sulfonic acid resin as catalyst and dimethylsulfoxide as solvent in a two-phase system.The effect of solvent,reaction temperature,reaction time and amount of catalyst on the rearrangement of cyclohexanone oxime were examined.The results indicate that the adsorption behavior of cyclohexanone oxime on sulfonic acid resin accords with Langmuir adsorption model and can be described by Langmuir isotherm and speed equation.And the conversion of cyclohexanone oxime can reach 100% with 86.2% of selectivity to e-caprolactam when the reaction was carried out at 130 ℃ for 6 h in dimethylsulfoxide solvent(m(catalyst)∶m(oxime) =1∶2(mass ratio)).This catalytic system involved environmentally harmless,mild reaction conditions,and the catalyst can be conveniently recovered for recycled use.