| Project/Area Number |
10440188
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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 |
Organic chemistry
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
TAKEUCHI Ken'ichi Kyoto University, Engineering, Professor, 工学研究科, 教授 (50026358)
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| Co-Investigator(Kenkyū-buntansha) |
OKAZAKI Takao Kyoto University, Engineering, Instructor, 工学研究科, 助手 (90301241)
KITAGAWA Toshikazu Kyoto University, Engineering, Associate Professor, 工学研究科, 助教授 (20183791)
KINOSHITA Tomomi Kyoto University, Engineering, Associate Professor, 工学研究科, 助教授 (10026289)
OHGA Yasushi Oita University, Engineering, Associate Professor, 工学部, 助教授 (60252508)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥11,800,000 (Direct Cost: ¥11,800,000)
Fiscal Year 1999: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1998: ¥8,400,000 (Direct Cost: ¥8,400,000)
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| Keywords | solvolysis / carbocation / carbanion / reaction rate / solcent effect / hydrophobic effect / ionic cleavage of C-C / bromoadamantanes / 炭素炭素結合イオン解離 / トロピリウムイオン / カルボカチオン中間体 / 塩化アルキル / 立体効果 / ハメット則 |
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| Research Abstract |
(1) Specific solvent effects in the generation-step of carbocations
The polarity effect that controls the solvolysis rates has been recognized as a linear free energy relationship, the so-called Grunwald-Winstein relationship. However, it has been shown that some substrates having a bulky hydrocarbon group show unusually slow rates of solvolysis and curved Grunwald-Winstein plots. The hydrophobic effect has been suggested as a probable origin of this behavior.
(2) Specific solvent effects in the reacting-step of carbocations
The first example was found for the elimination reaction that gives a propellane-type product after deprotonation of a cage-shaped, bridgehead carbocation. This reaction is markedly dependent upon the basicity of solvent and difficultly occurs in acidic solvents. Moreover, the deprotonation has only been found for the so-called α-keto cations.
(3) Specific solvent effects in the ionic dissociation of a C-C σ bond
Novel fullerene derivatives t-BuCィイD260ィエD2R were synthesized from stable hydrocarbon anion t-BuCィイD3-(/)60ィエD3 and substituted cyclopropenylium ions RィイD1+ィエD1. These hydrocarbons ionize in THF in the presence of small amounts of added DMSO. It was revealed that the Lewis-base type specific solvation of DMSO molecules facilitates the ionic dissociation.
(4) Specific solvent effects on the stability of hydrocarbon anions
It was revealed that the gas-phase stability of cyclopentadienide anion increases on introduction of alkyl substituents or condensed aromatic rings, whereas it decreases in solution. From these observations, the stabilization effect of solvent toward the cyclopentadienide anion has been quantitatively evaluated. The effect of alkyl and aromatic substituents to lower the anion stability in solution has also been quantitatively assessed.
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