Aerobic Ammoxidation of Cyclic Ketones to Dinitrile Products with Copper-Based Catalysts

Abstract

Adiponitrile (ADN) has wide applications, especially in the polymer industry. With the substantial and increasing global demand for ADN, effective production of ADN using safe and abundant starting materials is highly desirable but very challenging. Herein, we discovered that CuBr, combined with 1,10-phenanthroline (phen), could effectively promote the ammoxidation reaction of cyclohexanone to ADN with a yield of >99% using aqueous ammonia as the nitrogen source and O₂ as the terminal oxidant under mild reaction conditions (80 °C, 5 atm O₂). Moreover, cyclic ketones with various carbon numbers and substituent groups could also be converted into the corresponding dinitrile products with high yields. A detailed mechanistic study revealed that the reaction proceeded through a radical-mediated pathway, and the reason for the high selectivity to ADN was discussed. This study offers a new, simple, and cost-effective route to produce ADN and other dinitrile products.