- Bifunctional property of Pt nanoparticles deposited on TiO2 for the photocatalytic sp3C-sp3C cross-coupling reactions between THF and alkanes
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The photocatalytic sp3C-sp3C cross-coupling between tetrahydrofuran (THF) and various alkanes was accomplished with Pt loaded titanium oxide (Pt/TiO2) photocatalysts. The cross-coupling between THF and cyclohexane was systematically studied, which revealed that the reaction followed two routes: the main course was the photooxidation of both substrates on a Pt/TiO2 photocatalyst to generate radical species followed by their successive coupling; meanwhile, the minor one was a hybrid of photocatalysis by Pt/TiO2 and thermocatalysis by Pt metal nanoparticles. The activity of the Pt catalysis was suggested to consist in the activation of an sp3C-H bond in THF or alkane molecules adsorbed on its surface and promote the reaction between the activated molecules and photogenerated radical species. Thus, the Pt nanoparticles on TiO2 were believed to play a bifunctional role of an electron receiver as well as a metal catalyst.
- Tyagi, Akanksha,Yamamoto, Akira,Kato, Tatsuhisa,Yoshida, Hisao
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- Direct cross-coupling between alkenes and tetrahydrofuran with a platinum-loaded titanium oxide photocatalyst
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A Pt-loaded TiO2 photocatalyst successfully catalyzed the direct cross-coupling between various alkenes and tetrahydrofuran (THF) without any additional oxidizing agent. The reaction between cyclohexene and THF gave three cross-coupling products, namely, 2-cyclohexyltetrahydrofuran (A), 2-(cyclohex-2-en-1-yl)tetrahydrofuran (B) and 2-(cyclohex-1-en-1-yl)tetrahydrofuran (C), along with gaseous hydrogen. The mechanistic study revealed that these products were formed through different individual mechanisms: successive addition of two radical species, a 2-tetrahydrofuranyl radical and a hydrogen radical, to the double bond of cyclohexene for A, coupling of a 3-cyclohexenyl radical and a 2-tetrahydrofuranyl radical for B, and 2-tetrahydrofuranyl radical addition and hydrogen radical elimination at the double bond of cyclohexene for C. Among these three mechanisms, those for B and C are dehydrogenative. In this photocatalytic reaction system, since the cyclohexene molecule has enough reactivity, due to the localized π electron density, the Pt nanoparticles loaded on the TiO2 function not as a metal catalyst but as an electron receiver to enhance the charge separation, although the dehydrogenative cross-coupling of benzene with THF requires Pd metal catalysis.
- Tyagi, Akanksha,Yamamoto, Akira,Yamamoto, Muneaki,Yoshida, Tomoko,Yoshida, Hisao
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p. 2546 - 2556
(2018/06/01)
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- STAGES OF THE CONDENSATION OF 1,4-BUTANEDIOL IN THE MARKOVNIKOV - GUERBET REACTION
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The condensation of 1,4-butanediol in the presence of its sodium alcoholate and Ni/Cr2O3 leads to the formation of 4-hydroxybutanal and, from the latter, 3-formyl-1,4,7-heptanetriol.The latter exists in equilibrium with 1,7-dihydroxy-3-hydroxymethyl-4-heptanone and 2-hydroxy-2-(1-hydroxymethyl-3-hydroxypropyl)tetrahydrofuran.Dehydration of the latter with the formation of an endocyclic double bond and subsequent isomerization and reduction processes lead to the production of 2-(1-hydroxymethyl-3-hydroxypropyl)tetrahydrofuran.
- Lyubomilov, V. I.,Slesareva, L. A.,Pshenitsyna, V. P.,Slonim, I. Ya.,Bulai, A. Kh.
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p. 1871 - 1874
(2007/10/02)
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