| Project/Area Number |
06453041
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Organic chemistry
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| Research Institution | KUMAMOTO UNIVERSITY (1995)
Kyushu University (1994) |
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Principal Investigator |
TSUNO Yuho Kumamoto Universithy, Institute for Foundamented Research of Organic Chemistry, Professor, 教養部, 教授 (10029845)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIO Mizue Kyushu University, Institute for Foundemented Research of Organic Chemistry, Ass, 有機化学基礎研究センター, 助教授 (10029887)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥8,400,000 (Direct Cost: ¥8,400,000)
Fiscal Year 1995: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1994: ¥6,700,000 (Direct Cost: ¥6,700,000)
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| Keywords | Solvolysis Mechanism / Solvent Effect Analysis / Solvation / Transition State / Ion-Pair Return / O-18 Scrambling / Aryl-assisted Mechanism / PI-Delocalization / ベンジル位ソルボリシス / 脱溶媒和 |
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| Research Abstract |
The solvent effect on these solvolyses of aryl-assisted and benzylic solvolyses, despite the nucleophilically limiting nature, generally failed to give a single linear correlation with the Winstein-Grunwald Equation, using the adamantyl Y_<OTs> but showed characteristic dispersion for various binary aqueous solvent series. It is evident that developing charge at the reaction center in the transition state of benzylic k_c carbocationic process is highly delocalized through effective PI-overlapping with the aryl group, and this may cause a singificant loss of the highly oriented specific solvation at the charge-delocalized reaction center in comparison with that for aliphatic localized 2-adamantyl cation. The solvent polarity scale YDELTA based on p-methoxyneophyl solvolysis combined with the Y_<OTs> has shown a wide applicability to the solvolyses of benxylic arylalkyl tosylates involving varying degree of PI-delocalization interaction with the incipient carbocation charge ; log (k/k_O) = aY_<OTs> +bYDELTA. The equation can be applied to a series of aryl-assisted solvolyses in an extremely high precision, suggesting a continuous spectrum of k_c - kDELTA mechanisms. Benzylic k_c solvolyses can also be treated with linear combination of Y_<OTs> and YDELTA. Application of above generalized equation, including cN_<OTs> term, has also been extended to the nucleophilic solvent assisted solvolyses of alkyl and arylalkyl tosylates, e.g., for a series of substituted benzyl tosylates with limited success, particularly indicating no precise additivity (or non-linearity) for the nucleophilic solvent assistance.
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