Development and Application of Transition-metal Molecular Catalysts having Nano-structure

纳米结构过渡金属分子催化剂的开发及应用

基本信息

批准号：
14350470
负责人：
TSUJI Yasushi
金额：
$ 5.25万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

We have successfully developed nano-sized transition-metal molecular catalysts having dendrimers and bowl-shaped structures. They were compared with other common phosphine ligands in the rhodium-catalyzed hydrosilylation of ketones with a trisubstituted silane. A kinetic study at 24℃ indicated that a rhodium catalyst system with the bowl-shaped phosphine ligands realized 154,31, and 28 times faster hydrosilylation reaction. Furthermore, in homogeneous catalyst system, there is a persistent problem that metal aggregation and precipitation cause catalyst decomposition and considerable loss of catalytic activity Pd black formation is a typical example Pd catalysts are known to easily aggregate and form Pd black, although they realize a wide variety of useful reactions in organic synthesis. In order to overcome this intrinsic problem of homogeneous Pd catalysis, we explored a new class of Pd catalyst with adopting aerobic oxidation of alcohols as a probe reaction. We found a new catalyst system that suppresses the Pd black formation even under air and with a high substrate to catalyst molar ratio (S/C : more than 1000) in oxidation of alcohols. The novel pyridine derivatives having 2,3,4,5-tetraphenyiphenyl substituent and its higher dendritic unit at the 3-position of pyridine ring were found to be excellent ligands with Pd(OAc)_2 in the palladium-catalyzed air (balloon) oxidation of alcohols in toluene at 80℃ Comparison with structurally related pyridine ligands revealed that introduction of the 2,3,4,5-tetraphenylphenyl substituent at the 3-position of pyridine ring effectively suppresses the Pd black formation, maintaining the catalytic activity for a long time to give aldehydes or ketones as products in high yields.

我们已经成功地开发了具有树枝状聚合物和碗形结构的纳米大小的过渡金属催化剂。将它们与其他常见的磷酸配体在酮酸催化的酮基硅烷基化酮的氢硅烷化中，并具有三取代的硅烷。在24℃上进行的动力学研究表明，具有碗形磷酸配体的菱形催化剂系统实现了154,31，而氢硅烷基化反应更快28倍。此外，在均质催化剂系统中，存在一个持续的问题，即金属聚集和降水会导致催化剂分解和考虑催化活性PD黑色形成的丧失是典型的例子PD催化剂，它易于聚集并形成PD黑色，尽管它们意识到在有机合成中有多种有用的反应。为了克服均质PD催化的固有问题，我们探索了一种新的PD催化剂，并采用了醇的有氧氧化作为探针反应。我们发现了一种新的催化剂系统，该系统即使在空气下也抑制了PD黑色的形成，并且具有高基质与催化剂摩尔比（S/C：超过1000）的氧化氧化。发现具有2,3,4,5-四苯基苯基替代品及其在吡啶环3位处的较高的树突状单元的新型吡啶衍生物被发现是极好的配体PD（OAC）_2，在Palladium cataly-cataly-cataly-cataly-cataly-cataly-cataliz catigention Ploction Ploction Plig的耐受性的PD（OAC）_2中，在80岁的含量中，该含量是在80岁的含量中的氧化剂。在吡啶环3位处的2,3,4,5-四苯基苯基替代物中有效地抑制了PD黑色的形成，长时间保持催化活性，以高产率将醛或酮作为产物作为产物。