摘要/Abstract

以盐酸多巴胺，磷钼酸（PMo）为原料，通过离子交换和聚合作用形成一种有机-杂多酸杂化材料，在N₂条件下高温碳化制备出一种新型多孔碳球封装纳米碳化钼催化剂PDA-PMo-800.利用傅里叶变换红外（FT-IR），N₂吸脱附等温仪（BET），扫描电子显微镜（SEM），透射电子显微镜（TEM），X射线粉末衍射（XRD），拉曼光谱仪（Raman），热重分析仪（TG），能谱仪（EDS）对催化剂进行表征与分析.结果显示：催化剂PDA-PMo-800具有规整的花状球体形貌以及较高的比表面积（102 m²/g），纳米碳化钼颗粒（3~4 nm）均匀地分布在多孔碳球骨架内.在无溶剂以氧气为氧化剂的条件下，将该催化剂应用于苄胺的氧化偶联反应合成亚胺，实现较高的转化率及选择性，且催化剂可以多次重复使用并保持较高的催化活性.
关键词: 碳化钼, 盐酸多巴胺, 磷钼酸, 多金属氧酸盐, 苄胺偶联反应
Imines and their derivatives are versatile chemical intermediates for the synthesis of pharmaceuticals, polymer materials, biologicals and so on. The oxidative coupling of amines was demonstrated to be a promising one pot synthetic procedure for imines, and considerable efforts have been devoted to it. A new type of catalyst based on Mo₂C was successfully prepared by roasting the mixture synthesized by using the interaction between ionic bonds with dopamine (DA) and phosphomolybdate (PMo). In a typical procedure, solid product was pyrolyzed in a tube furnace at 800℃ for 3 h in N₂ with heating rate of 5℃/min, and the sample PDA-PMo-800 was achieved. The catalyst was characterized and analyzed by Fourier transform infrared (FT-IR), N₂ adsorption desorption (BET), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and Raman spectrometer (Raman), thermo gravimetric analyzer (TG), energy dispersive spectrometer (EDS). It was found that the catalyst had morphologies of flower shaped spheres and certain specific surface area (102 m²·g^-1). As a catalyst, it can be used in the oxidation coupling reaction of benzyl amine to synthesize the imine under the condition of no solvent and oxygen as oxidant. Typically, amine (5 mmol) and catalyst (0.03 g) was added into a 25 mL sealed round-bottomed flask and kept vigorously stirring at 100℃ under O₂ balloon for 10 h. After completion, the catalyst was separated by centrifugation with N,N-dimethylformamide, washed with ethanol, dried in a vacuum, and reused for the next time. The filtrate was identified by GC-MS, and the conversion and yield were analyzed by GC (SP-6890A) equipped with a FID detector. The results showed that a high conversion rate and selection rate can be achieved. And the catalyst can be used repeatedly and maintained a high conversion rate under the same conditions. The successful design of this catalyst not only combines metal materials with organic materials, but also makes a preparation for transition metals to replace noble metals. In addition, carbonized metal was used as a catalyst for coupling reaction, which provided a new idea for the application of carbonized metals to organic reactions.
Key words: molybdenum carbide, dopamine hydrochloride, phosphomolybdate, polyoxometalates, benzylamine coupling reaction


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