1987 Fiscal Year Final Research Report Summary
Molecular designing of catalytic electron mediator of hydrophobic stable ion-pair form.
| Project/Area Number |
61550643
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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 |
Synthetic chemistry
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| Research Institution | Kyushu University |
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Principal Investigator |
KOBAYASHI Hiroshi Institute of Advanced Material Study, 機能物質科学研究所, 教授 (10037731)
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| Co-Investigator(Kenkyū-buntansha) |
ICHIKAWA Junji Institute of Advanced Material Study, 機能物質科学研究所, 助手 (70184611)
SONODA Takaaki Institute of Advanced Material Study, 機能物質科学研究所, 助教授 (90108770)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Hydrophobic stable ion pair / 4,4'-bipyridine radical cation / Tetrakis[3,5-bis(trifluorormethyl)phenyl] borate ion / Electron mediator / Proton-electron mediator / 酸化還元電位 |
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| Research Abstract |
Alkylviologen (N-alkylbipyridinium) derivatives were molecular-designed so that they could carry the same number of electrons and protons (hydrogen radical equivalent) concurrently. By combining with lipophilic organic anion, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion (TFPB) which we developed prediously, the bipyridinium derivatives gave stable ion pairs soluble in hydrophobic organic solvents. Their functions as the catalytic electron- and hydrogen--transporting agents were characterized in organic solvents.
The results are summarized as follows:
(1) As the hydrogen-transporting agents of bipyridinium--type, 1-butyl-4-(4-pyridyl)pyridinium (I), 1,3-bis[4-(4-pyridyl)pyridinio]propane (II), and 1,8-bis[4-(4-pyridyl]pyridiniomethyl]naphthalene (III) were synthesized.
(2) The redox potentials of (I), (II), and (III) were measured by cyclic voltammetry in the region of 1<pH<11. Their pH-dependence seemed to be related with the pK_a of the corresponding conjugate acids.
(3) Ion-pair
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extraction of the bipyridinium derivatives with TFPB were examined in the water-organic solvent two-phase systems. The cation/anion ratios of the extracted ion pairs were discussed in terms of the hydrophobic effect of TFPB.
(4) On the bases of electronic spectra of bipyridinium derivatives in aqueous- and organic solvent phases, the structures of their radical cations in the solution phases were considered in terms of the intramolecular charge-transfer interaction between the radical and cationic moieties and the bulky steric effect due to TFPB.
(5) The reaction conditions and procedures were established on the reduction of the bipyridine derivatives, (I), (II), and (III), with zinc under acid conditions, to the corresponding radical cations.
(6) Comparisons of the reaction efficiencies of hydrogen transfer to the enedione and electron transfer to the dibromide in aprotic solvents indicated that the concurrent transfer of electron and proton was essential to proceed the chemoselective hydrogenation of olefinic bond and the mechanism was given. Also the use of catalytic reductions were exemplified with a certain range of substrates. Less
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Research Products
(4 results)
