- Hydrophobic acceleration of electron transfer processes
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Electron transfer processes between 1-α-naphthyl-3-oxa-alkanes (1-n, n = 1, 8, 12, 16) and 2-alkyl-3,5,6-trichloro-1,4-benzoquinones (2-n, n = 8, 12, 16) facilitated by hydrophobic-lipophilic interactions (HLI) have been investigated by means of fluorescence spectroscopy in dioxane-H2O systems of different ψ values, where ψ is the volume fraction of the organic component of an aquiorgano mixture. Three lines of evidence, namely, EPR, UV-vis, and fluorescence quenching, indicate that electron transfer between 1-12 and 2-12 has occurred. Furthermore, both UV-vis evidence and the near constancy of the life time τ of 1-12* in the presence of different concentrations of the quencher 2-12 show that the electron transfer is preceded by preassociation, i.e., the quenching process is static. Therefore, the extent of HLI-driven coaggregation (preassociation) between the donors and the acceptors may be assessed from the Stern-Volmer slopes (Ksv). The chain-length effect, and possibly also a chain-foldability effect, has been observed. A notable observation is the importance of solvent aggregating power (SAgP) effect, which is indicated by the surge of Ksv values at ψ ≤ 0.40 (dioxane-H2O) for monomeric 1-12.
- Shi, Ji-Liang,Chen, Xin,Jiang, Xi-Kui
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- Radical addition to 1,4-benzoquinones: Addition at O- versus C-atom
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(Diagram presented) Addition of alkyl radicals generated from B-alkylcatecholboranes onto 1,4-benzoquinones leads to substituted hydroquinones in good overall yields. Formation of aryl ethers via a unique radical addition to the oxygen atom of the enone system is the main reaction when bulky secondary and tertiary alkyl radicals are used. Less hindered secondary and primary radicals give the expected 1,4-conjugate addition products.
- Kumli, Eveline,Montermini, Florian,Renaud, Philippe
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- Synthesis of 2-substituted hydroquinone derivatives from 1,4-benzoquinone and allyl ethers
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B-Alkylpinacolboranes, derived from rhodium-catalyzed hydroboration of allyl ethers with pinacolborane, react with 1,4-benzoquinone under acidic, oxidizing conditions, to afford, after subsequent hydrogenation, 2-substituted hydroquinones in isolated, pur
- Kaurich, Kevin J.,Deck, Paul A.
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p. 2191 - 2196
(2018/03/28)
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