| Project/Area Number |
05640596
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Organic chemistry
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| Research Institution | Yokohama National University |
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Principal Investigator |
SUEZAWA Hiroko Yokohama National University, Faculty of Engineering, Assistant, 工学部, 教務職員 (30251771)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1993: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | multinuclear NMR / ionic interaction / contact ion pair / electronic interaction / diaza-aromatics |
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| Research Abstract |
The NMR line widths of ^<14>N nuclei in cations and ^<35>Cl, ^<81>Br nuclei of halide ions of several pyridnium and anilinium halides were measuresd in aqueous solutions of rather high concentration range. Intrinsic line width (w) , defined by W=DELTAnu_<1/2>T/eta was shown to be convenient for correlating the line widths of quadrupolar nuclei with molecular sizes and other properties of these cations. In the W vs. concentration plots of halide ions, a characteristic plateau whose height reflected the size of the nitrogen countercation was observed in the concentration range from 1.5 to 3m. These findings suggest the presence of contact ion pairs in this concentration range.
In this report, we extended the discussion to the ionic interactions in aqueous solutions of diaza-aromatic comounds. The W values of halide ions in the plateau region(at 2 m)were correlated with the sizes of the nitrogen cations, since the W of halide ions should be a diaza-aromatics were shown to have to have a good linear relation with the value (a^3) of the cations similarly to monobasic azabenzens and -naphthalenes. In the case of quinoxaline and some derivatives, the W value of halide ions was fairly lower than monoazanaphthalenes which have nearly same molecular volume with quinoxaline. This sort of diazanaphthalenes are considered to be unable to from ion pairs completely in aqueous solutions, because of their lower pK_a value. The fact that the pK_a value is roughly correlated with the W of halide ions is suggestive in this respect.
Substituent effects on ^<15>N-NMR chemical shift of p- and m-substituted anilides were also exa-mined in order to clarify the electronic interaction and local pi-polarization in the molecules.
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