2003 Fiscal Year Final Research Report Summary
Development and Application of Transition-metal Molecular Catalysts having Nano-structure
| Project/Area Number |
14350470
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Synthetic chemistry
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
TSUJI Yasushi Hokkaido Univ., Catalysis Research Center, Prof., 触媒化学研究センター, 教授 (30144330)
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| Co-Investigator(Kenkyū-buntansha) |
OBORA Yasushi Hokkaido Univ., Catalysis Research Center, Inst., 触媒化学研究センター, 助手 (50312418)
TOKUNAGA Makoto Hokkaido Univ., Catalysis Research Center, Asso.Prof., 触媒化学研究センター, 助教授 (40301767)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Dendrimer / Nano-size / Molecular modeling / Palladium catalyst / Rhodium catalyst / Air oxidation / Platinum (0) complex / Phosphine |
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| Research Abstract |
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.
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Research Products
(13 results)
