Departamento de Química, Universidade Federal de Santa Catarina, INCT-Catalysis , Florianópolis, Santa Catarina 88040-900, Brazil.
J Org Chem. 2014 Mar 21;79(6):2574-9. doi: 10.1021/jo5000362. Epub 2014 Feb 27.
Palladium nanoparticles (NPs) stabilized by a zwitterionic surfactant are revealed here to be good catalysts for the reductive amination of benzaldehydes using formate salts as hydrogen donors in aqueous isopropanol. In terms of environmental impact and economy, metallic NPs offer several advantages over homogeneous and traditional heterogeneous catalysts. NPs usually display greater activity due to the increased metal surface area and sometimes exhibit enhanced selectivity. Thus, it is possible to use very low loadings of expensive metal. The methodology eliminates the use of a hydrogen gas atmosphere or toxic or expensive reagents. A range of aromatic aldehydes were converted to benzylamines when reacted with primary and secondary amines in the presence of the Pd NPs, which also displayed good activity when supported on alumina. In every case, the Pd NPs could be easily recovered and reused up to three more times, and at the end of the process, the product was metal-free.
本文研究了一种由两性离子表面活性剂稳定的钯纳米粒子（NPs），它可作为催化剂，在水-异丙醇体系中，以甲酸盐作为氢供体，用于苯甲醛的还原胺化反应。与均相和传统多相催化剂相比，金属 NPs 在环境影响和经济性方面具有许多优势。由于金属表面积的增加，NPs 通常表现出更高的活性，有时还表现出更高的选择性。因此，可以使用非常低负载量的昂贵金属。该方法消除了使用氢气气氛或有毒或昂贵试剂的需要。一系列芳香醛与伯胺和仲胺反应时，在 Pd NPs 的存在下转化为苄胺，Pd NPs 负载在氧化铝上时也表现出很好的活性。在每种情况下，Pd NPs 都可以很容易地回收和再使用三次以上，而且在反应结束时，产物中不含金属。
