Developing robust and facile catalytic systems for converting nitroaromatic compounds to NH2-containing compounds are of importance to decrease or even eliminate their toxicity or risk in the environment. In view of in situ formed metal nanoparticles, the metal ion (Cu2+, Ag+, AuCl4−, Co2+ and Ni2+)/NaBH4 systems were employed to catalyze the reduction reaction of nitroaromatic compounds. By employing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as a model reaction, the effects of concentration of NaBH4, 4-NP and metal ions on the rate constants of the catalytic reduction reactions were systematically investigated. Apparent activation energies of these metal ion/NaBH4 catalytic systems were further measured and compared. In situ formed metal NPs could be characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Furthermore, these metal ion/NaBH4 systems were successfully employed to catalyze the reduction reaction of a series of other nitroaromatic compounds. These metal ion/NaBH4 catalytic systems investigated in this protocol are simple and do not require the preparation of metal nanoparticles in advance, compared with previous related reports.
开发强健且简便的催化体系,将硝基芳香化合物转化为含NH2的化合物,对于降低甚至消除它们在环境中的毒性或风险具有重要意义。鉴于原位形成的
金属纳米颗粒,采用了
金属离子(Cu2+、Ag+、
AuCl4−、Co2+和Ni2+)/NaBH4体系来催化硝基芳香化合物的还原反应。通过以4-
硝基苯酚(4-NP)还原为4-
氨基苯酚(4-AP)为模型反应,系统地研究了NaBH4、4-NP和
金属离子浓度对催化还原反应速率常数的影响。进一步测量并比较了这些
金属离子/NaBH4催化体系的表观活化能。原位形成的
金属NPs可以通过X射线衍射(XRD)和透射电子显微镜(
TEM)进行表征。此外,这些
金属离子/NaBH4体系成功地用于催化一系列其他硝基芳香化合物的还原反应。与之前的相关报道相比,本研究所调查的这些
金属离子/NaBH4催化体系简单,不需要提前制备
金属纳米颗粒。