氢键驱动的二苯甲酮肟Beckmann重排反应研究

Hydrogen Bond Driven Beckmann Rearrangement of Diphenyl-ketoxime

在充分分析Beckmann重排反应机理的基础上,通过设计合成氨基功能化介孔氧化硅,对之进行酸化,获得质子化氨基功能化介孔氧化硅材料HAF-SBA-15.利用HAF-SBA-15中的质子氢与肟羟基氧上的孤对电子形成配位键及N、H、O间形成的氢键,协同弱化肟羟基与N之间的结合力,加速肟羟基离去及碳正离子的形成,从而促进Beckmann重排反应.以二苯甲酮为底物合成二苯甲酮肟,在HAF-SBA-15催化下进行Beckmann重排反应,结果证明二苯甲酮肟转化率较大、获得的N-苯基苯甲酰胺纯度较高.此外,还探索溶剂类型、反应温度、催化剂用量等因素对二苯甲酮肟Beckmann重排反应的影响,获得最佳反应条件,该反应条件温和,50℃即可发生高效的二苯甲酮肟Beckmann重排反应.

Based on fully analyzing the mechanism of Beckmann rearrangement reaction,protonated amino functional mesoporous silica materials HAF-SBA-15 were obtained via acidizing amino functional mesoporous silica.The binding force between hydroxamic hydroxyl group and N was synergistically weakened by the coordination bond formed by proton hydrogen in HAF-SBA-15,lone pair electrons in hydroxyl hydroxoxoxime and hydrogen bonds formed between N,H and O.It synergistically weakenef the binding force between oxime hydroxyl and N,accelerated the departure of oxime hydroxyl and the formation of carbon positive ions,,and promoted the Beckmann rearrangement reaction.Catalyzed by HAF-SBA-15,N-benzo-phenamide was synthesized via the Beckmann rearrangement of diphenyl-ketoxime.The results showed that the conversion rate of diphenyl-ketoxime is high and the obtained N-benzophenamide is pure.Furthermore,effect of solvent type,reaction temperature,and catalyst dosage on the Beckmann rearrangement of diphenyl-ketoxime was investigated,and the optimum reaction conditions were obtained.The results illustrated that the optimum reaction conditions are mild because Beckmann rearrangement of diphenyl-ketoxime was efficiently carried out at 50℃.