摘要
炔烃水合制备酮是有机合成中最重要的官能团转换方法之一,在现代化工生产中具有广泛的应用~([1])。传统炔烃水合反应的催化剂如汞盐类~([2])具有高毒性,对环境污染严重。新开发的金属有机催化剂~([3.4])价格昂贵,且难以从反应体系中分离,循环利用困难。因此,开发高效绿色的可循环催化剂具有重要的研究意义。本研究制备了一种新型的双功能炔烃水合反应催化剂(Au–TiO_2/SO_4~(2–)–RGO)。超精细的金纳米颗粒(大约4.5纳米)首先被沉积在层状的二氧化钛-还原氧化石墨烯载体上。在微波辅助作用下,二氧化钛表面被酸化而形成SO42–固体酸。实验结果表明,双功能催化剂对苯乙炔水合反应具有增强的催化效果(收率为100%)。在还原氧化石墨烯载体的固载作用下,超精细的金纳米颗粒和表面SO_4~(2–)酸性位点的双功能作用是其优异催化性能的重要原因。催化剂可以通过过滤或离心等简单操作进行分离,并循环利用数次。本研究为新型的多功能催化剂的制备提供思路和方法。
The hydration reaction is very important in organic synthesis, which can produce valuable carbonyl derivatives from accessible alkynyl substrates. Transitional catalysts such as mercury salts or gold complexes suffer from neither strong toxicity nor difficulty of recycle. Therefore, developing green recyclable catalysts is of great significance. Herein, we synthesized a novel bifunctional composite(Au–TiO_2/SO_4~(2–)–RGO) for hydration reactions. Gold nanoparticles(AuNPs, ~4.5 nm) were grown on a layered titania(TiO_2) and reduced graphene(RGO) hybrid. With the assistance of microwave, solid acid SO_4~(2–) was in-situ formed on the surface of TiO_2. The resulting Au–TiO_2/SO_4~(2–)–RGO was determined as an enhanced catalyst for the hydration of phenylacetylene(yield 100%). The bifunctional untra-fine AuNPs and acid sites account for the excellent performance, and the versatile RGO serves as an ideal substrate. Moreover, the catalyst could also be recycled and reused for at least 5 times without obvious deactivation. The novel catalyst design strategy is readily extended to other reaction systems with amazing catalytic performance.
引文
[1]Zhu,X.,Wang,W.and Li X.J.Am.Chem.Soc.,2011,133:11632.
[2]Wang,S.,Miao,C.,Wang W.,Lei Z.and Sun W.Chin.J.Catal.,2014,35:1695.
[3]Xu,L.,Liu,L.,Wang,Z.,and Fu,X.Chem.Commun.,2015,51:11896.
[4]F.Li,N.Wang,L.Lu and G.Zhu,J.Org.Chem.,2015,80:3538.