2005 Fiscal Year Final Research Report Summary
Preparation of Novel Silsesquioxane-Based Materials with Characteristic Catalytic Functions
| Project/Area Number |
16560676
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Catalyst/Resource chemical process
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
WADA Kenji Kyoto Univ., Grad.School Engineering, Lecturer, 工学研究科, 講師 (10243049)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Metal-Containing Silsesquioxanes / Microporous Oxides / Solid Acidic Catalysts / Caged Silsesquioxanes / Dendrimers / Epoxidation of Alkenes / Oxidation of Alcohols / Organic-Inorganic Hybrid Materials |
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| Research Abstract |
Caged metal-containing silsesquioxanes have attracted much attention from the viewpoint of discrete, well-defined soluble model compounds of the transition metal-containing siliceous heterogeneous catalysts. In the present work, synthesis of a series of silsesquioxanes with novel structures have been performed as well as the preparation of precursors of organic-inorganic hybrid materials for catalysts. Preparation of porous oxide catalysts utilizing silsesquioxanes was also examined.
1. Preparation of Novel Caged Silsesquioxanes
The intramolecular cyclotrimerization of a half-caged silsesquixane with three ethynylsilyl groups gave novel caged silsesquioxanes composed of a siloxane framework and a 1,3,5-substituted benzene ring and a 1,2,4-substituted one in a combined yield of 52% by the reaction at 170℃ for 16 h in the presence of 15.0 mol% of CpCo(CO)_2 catalyst.
2. Synthesis of Dendritic or Starburst-type Silsesquioxanes
The Pt-catalyzed hydrosilylation of octakis(dimethylsiloxy)silsesq
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uioxane ((HSi(CH_3)_2)_8Si_8O_<12>) with ten equivalents of a silsesquloxane disilanol with a dimethylvinylsilyl group in toluene afforded a starburst-type silsesquioxane containing 16 silanol groups in 83% yield. A starburst-type silsesquioxane with sixteen Si-H groups and that bearing phenyl boryl groups have been synthesized in good yields. Further hydrosilylative reaction with a silsesquioxane bearing allylsilyl groups successfully yields the expected 2nd generation dendrimer in the yield of 63%.
3. Preparation of Porous Acidic Catalysts from Aluminosilsesquioxanes
The catalytic activities of a series of porous oxides prepared from aluminosilsesquioxanes for the cracking of hydrocarbons have been examined. Among the oxides examined, the oxides prepared from aluminum-bridged silsesquioxanes show excellent catalytic activities for the cracking of cumene even at low reaction temperatures of around 523 K, indicating exceptionally high activities in spite of their amorphous nature.
4. Preparation of Palladium Oxide Nanoparticles-Encapsulating Porous Oxide Catalysts for Oxidation Utilizing a Silsesquioxane Ligand
The controlled calcination of Pd complexes bearing a silsesquioxane-amine ligand at 823 K in air stream for 4 h afforded porous silicas of high surface areas and uniformly controlled micropores of ca. 0.6 nm diameter encapsulating monodispersed palladium oxide nanoparticles. The calcination after the impregnation of palladium-silsesquioxane complexes onto various supports afforded oxides with both meso- and micropores. These catalysts showed excellent catalytic activities towards the aerobic oxidation of benzyl alcohol, especially in water. Less
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