酸性离子液体-ZnCl2催化环己酮肟液相Beckmann重排反应

摘要

在乙腈介质中,由酸性离子液体和ZnCl2组成的催化体系,可以高效地实现对环己酮肟液相Beckmann重排制己内酰胺的反应.反应过程中生成的唯一副产物环己酮,可以通过氨氧化反应生成原料环己酮肟.考察了溶剂种类、反应温度、反应时间、离子液体用量和ZnCl2用量对环己酮肟重排反应性能的影响.确定了适宜的反应条件;HSO3-b-N(CH)3]HSO4 0.5 mmol,ZnCl2 15 mmol,乙腈10 mL,环己酮肟10 mmol,反应温度80℃,反应时间4h.此条件下,环己酮肟转化率达100％,己内酰胺收率为94.9％.利用在线反应红外光谱仪(React IR IC-10)研究了该催化体系下环己酮肟重捧反应机理.%The liquid-phase Beckmann rearrangement of cyclohexanone oxime was effectively realized to prepare e-caprolactam by using acidic ionic liquid-zinc chloride(IL-ZnCl2) catalytic system in acetonitrile. The only by-product, cyclohexanone, could convert back to the raw material, cyclohexanone oxime, by ammoximation reactionThe effects of solvents, reaction temperature, reaction time, the amount of IL, the amount of ZnCl2 on the Beckmann rearrangement were studied. The optimized conditions were:[HSO3-b-N(CH3)3]HSO4 0.5mmol, ZnCl2 15 mmol, acetonitrile 10 mL, cyclohexanone oxime 10 mmol, 80℃, 4 h. The conversation of cyclohexanone oxime can reach 100%, the yield of e-caprolactam can reach 94.9%.The reaction mechanism of cyclohexanone oxime rearrangement over IL-ZnCl2 catalyst was also investigated by React IR IC-10.