Direct catalytic synthesis of ε-caprolactam from cyclohexanol using [n-C16H33N (CH3)3]H2PW12O40 as a catalyst

•ε-Caprolactam was synthesized directly from cyclohexanol via a tandem process.•[n-C16H33N(CH3)3]H2PW12O40 shows high catalytic performance.•A ε-caprolactam yield of 73.9% was obtained with a cyclohexanol conversion of 97.1%.•[n-C16H33N(CH3)3]H2PW12O40 can be easily recycled without loss of activity.

ε-Caprolactam was synthesized directly from cyclohexanol via a tandem catalytic process using [n-C16H33N(CH3)3]H2PW12O40 as a catalyst. The highly efficient performance of the catalysts is due to the phase-transfer function of cation, improved coordination with peroxotungsten during oxidation and stabilization function of heteropoly anion on the intermediate formed during Beckmann rearrangement. A ε-caprolactam yield of 73.9% was obtained with a cyclohexanol conversion of 97.1% under optimized conditions.

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