- Photocatalysis in dimethyl carbonate green solvent: Degradation and partial oxidation of phenanthrene on supported TiO2
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Dimethyl carbonate (DMC) is here proposed-for the first time-as a green organic solvent for photocatalytic synthesis. In this work, the photocatalytic partial oxidation of phenanthrene in dimethyl carbonate (DMC) by using anatase TiO2as the photocatalyst is described as paradigmatic example of a green synthetic process starting from polycyclic aromatic hydrocarbons (PAHs). For comparison, the same reaction carried out also in ethanol, 1-propanol or 2-propanol is reported. The use of DMC as the solvent allowed us to achieve 19% and 23% selectivity towards 9-fluorenone and 6H-benzo[c]chromen-6-one, respectively. The proposed approach may represent both a new green synthetic process and an environmentally friendly route to degradation of PAHs. This journal is
- Bellardita,Loddo,Mele,Panzeri,Parrino,Pibiri,Palmisano
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p. 40859 - 40864
(2015/01/08)
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- On the redox reaction of 1,2-bis(diphenylphosphino) alkanes toward o -, and p-quinones
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The reaction of 1,2-bis(diphenylphosphino)ethane with substituted o-benzo-quinones afforded new bis(6-hydroxycyclohexa-2,4-dienone) derivatives. Treatment of the same reagent with o-naphthoquinone, phenanthrenequinone, and acenaphthenequinone gave the res
- Boulos, Leila S.,Ewies, Ewies F.,Fahmy, Amin F. M.
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p. 726 - 738
(2013/07/26)
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- Photochemical reactions of coenzyme PQQ (pyrroloquinolinequinone) and analogues with benzyl alcohol derivatives via photoinduced electron transfer
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Photochemical redox reactions of the trimethyl ester of coenzyme PQQ (PQQTME) with benzyl alcohol derivatives (ArCH2OH), tetrahydrofuran, and 1,4-cyclohexadiene occur efficiently under visible light irradiation in MeCN to yield PQQTMEH2 (reduced PQQTME in the quinol form) and the corresponding dehydrogenated products (ArCHO, furan, and benzene) quantitatively. A similar photochemical oxidation of benzyl alcohols also occurs with phenanthrolinequinone derivatives (PTQ), benzoquinolinequinone derivatives (BQQ), and phenanthrenequinone (PQ). PQQTME and the analogues are essentially nonfluorescent in MeCN, and the photochemical reaction of the o-quinones is retarded significantly in the presence of molecular oxygen. Transient absorption spectra of the triplet excited states of the o-quinones were detected in laser flash photolysis of the MeCN solutions. From the decay of T-T spectra were determined the lifetimes of the triplet excited states of the o-quinones. The quenching rate constants of the triplet excited states by benzyl alcohols agree with the observed rate constants of the photochemical reduction of the o-quinones with the same substrates determined from the saturated dependence of quantum yields on the benzyl alcohol concentrations. Such an agreement confirms that the photochemical reaction proceeds via the triplet excited state of the quinones. Dependence of the observed rate constants kobs of the photochemical redox reaction on the one-electron oxidation potential Eoox of the substrates as well as the results of kinetic deuterium isotopic study indicates that the photochemical redox reactions between the o-quinones and the substrates proceed via photoinduced electron transfer from the substrate to the triplet excited state of the o-quinone, followed by proton and hydrogen atom transfer to yield the quinol and the corresponding oxidation products. The transient absorption spectra of the radical ion pair formed in the photoinduced electron transfer have been detected successfully in laser flash photolysis of the o-quinone - benzyl alcohol systems.
- Fukuzumi, Shunichi,Itoh, Shinobu,Komori, Takashi,Suenobu, Tomoyoshi,Ishida, Akito,Fujitsuka, Mamoru,Ito, Osamu
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p. 8435 - 8443
(2007/10/03)
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