| Project/Area Number |
02403010
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
有機化学一般
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| Research Institution | KYUSHU UNIVERSITY (1991-1993)
Okazaki National Research Institutes (1990) |
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Principal Investigator |
TSUNO Yuho Kyushu University, Institute for Fundamental Research in Organic Chemmistry, Professor, 理学部, 教授 (10029845)
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| Co-Investigator(Kenkyū-buntansha) |
藤尾 瑞枝 九州大学, 理学部, 助手 (10029887)
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| Project Period (FY) |
1990 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥39,500,000 (Direct Cost: ¥39,500,000)
Fiscal Year 1993: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1992: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1991: ¥8,000,000 (Direct Cost: ¥8,000,000)
Fiscal Year 1990: ¥27,500,000 (Direct Cost: ¥27,500,000)
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| Keywords | Solvolysis Mechanism / Ion-Pair Return / Ion-Pair Intermediates / O-18 Scrambling / Nucleophilic Displacement / Aryl-assisted Mechanism / Solvent Effect / Oー18スクランブリング / ソルボリシス / 反応機構 / ^<18>Oースクランブリング / 同位体化学シフト |
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| Research Abstract |
The splitting in the C-13 NMR signals, induced by isotopic oxygen substitution O-16/O-18, was utilized successfully to determine quantitatively the extent of O-18 scrambling within three oxygens in the sulfonate moiety. This method was applied to the investigation of return process in the solvolysis of various arylalkyl tosylates. The solvent dependency of (1-F) value in adamantyl solvolyses shows in good accordance with that of alpha-t-butylbenzyl one. Accordingly the ion-pair return scarcely affects the result of the solvent effect analysis of alpha-t-butyl benzyl solvolysis based on 2-adamantyl Y_<OTs>.
Despite the nucleophilically limiting nature of aryl-assisted and benzylic solvolyses, the solvent effect on these solvolyses 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. Developing charge at the reaction center in the transition state of benzy
… More
lic k_c carbocationic process is highly delocalized through effective pi-overlapping with aryl group, and this may cause a significant loss of the highly oriented specific solvation at the reaction center in comparison with that for aliphatic localized 2-adamantyl cation. The solvent polarity scale Y_<DELTA> based on p-methoxyneophyl solvolysis combined with the Y_<OTs> has shown a wide applicability to the solvolyses of benzylic arylalkyl tosylates involving varying degree of pi-delocalization interaction with the incipient carbocation charge ; log (k/k_o) = aY_<OTs> + bY_<DELTA>. The equation can be applied to various series of aryl-assisted solvolyses in an extremely high precision, suggesting a continuous spectrum of k_c-k_<DELTA> mechanisms. Benzylic k_c solvolyses can also be treated with linear combination of Y_<OTs> and Y_<DELTA>. Application of revised equation, aY_<OTs> and bY_<DELTA> including cN_<OTs> term has also been extended to the nucleophilic solvolyses of alkyl and arylalkyl tosylates, with limited success, indicating no precise additivity for the nucleophilic solvent involvement. Less
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