A hydrophilic heterogeneous cobalt catalyst for fluoride-free Hiyama, Suzuki, Heck and Hirao cross-coupling reactions in water,Green Chemistry

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A hydrophilic heterogeneous cobalt catalyst for fluoride-free Hiyama, Suzuki, Heck and Hirao cross-coupling reactions in water
Green Chemistry ( IF 9.3 ) Pub Date : 2020/01/29 , DOI: 10.1039/c9gc03455b
Sara Sobhani _{1,

2,

3,

4,

5} , Hadis Hosseini Moghadam _{1,

2,

3,

4,

5} , Jørgen Skibsted _{6,

7,

8,

9} , José Miguel Sansano _{10,

11,

12,

13,

14}

Affiliation

A hydrophilic heterogeneous cobalt catalyst of chitosan, denoted as mTEG-CS-Co-Schiff-base, has been successfully prepared. This newly synthesized catalyst was characterized by different methods such as XRD, FE-SEM, TEM, TGA, FT-IR, ¹³C{¹H} CP/MAS NMR, XPS and ICP analyses. The catalyst displayed excellent activity for the palladium and fluoride-free Hiyama, Suzuki, Heck and Hirao reactions of various aryl iodides, bromides and chlorides (i.e., the most challenging aryl halides which are cheaper and more widely available than aryl iodides and bromides) in water. The presence of triethylene glycol tags with hydrophilic character on the Co-complex supported on chitosan provides dispersion of the catalyst particles in water, which leads to higher catalytic performance and also facile catalyst recovery by successive extraction. It was reused for at least six successive runs without any discernible decrease in its catalytic activity or any remarkable changes in catalyst structure. The use of water as a green solvent, without requiring any additive or organic solvent, as well as use of a low cost and abundant cobalt catalyst instead of expensive Pd catalysts along with the catalyst recovery and scalability, make this method favorable from environmental and economic points of view for the C–C and C(sp²)–P coupling reactions. Notably, this is the first report on the application of a cobalt catalyst in Hiyama reactions.

中文翻译：

用于水中无氟Hiyama，Suzuki，Heck和Hirao交叉偶联反应的亲水性多相钴催化剂

已成功制备了壳聚糖的亲水多相钴催化剂，称为mTEG-CS-Co-Schiff-碱。这种新合成的催化剂通过不同的方法进行了表征，例如XRD，FE-SEM，TEM，TGA，FT-IR，¹³ C { ¹ H} CP / MAS NMR，XPS和ICP分析。该催化剂对各种芳基碘化物，溴化物和氯化物（即，即钯）的无钯和无氟的Hiyama，Suzuki，Heck和Hirao反应显示出优异的活性。，这是最具挑战性的芳基卤化物，比水中的芳基碘化物和溴化物更便宜，更广泛地得到。在壳聚糖上负载的Co配合物上具有亲水特性的三甘醇标签的存在使催化剂颗粒分散在水中，这导致更高的催化性能，并且通过连续萃取也易于回收催化剂。至少连续六次重复使用了该催化剂，但催化活性没有明显下降，催化剂结构也没有明显变化。使用水作为绿色溶剂，不需要任何添加剂或有机溶剂，以及使用低成本和丰富的钴催化剂代替昂贵的Pd催化剂，以及催化剂的回收率和可扩展性，²）–P偶联反应。值得注意的是，这是关于钴催化剂在Hiyama反应中的应用的首次报道。

更新日期：2020-02-24

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