Aerobic Photooxidation in Water by Polyoxotungstates: The Case of Uracil

Bonchio, Marcella; Carraro, Mauro; Conte, Valeria; Scorrano, Gianfranco

doi:10.1002/ejoc.200500418

Cited by 9 publications

(10 citation statements)

References 55 publications

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“…The catalytic activity and the stability under turnover regime of the different hybrid membranes has been assessed by performing a series of photooxidation experiments in water using cis-cyclohexan-1,2-diol as model substrate [36] (see experimental section). Under the conditions explored, substrate conversion is achieved in the range 30-60% leading to a mixture of oxygenated products among which 2-hydroxy-cyclohexanone has been identified as the major species.…”

Section: Polymeric Membranes Embedding Decatungstatementioning

confidence: 99%

Hybrid photocatalytic membranes embedding decatungstate for heterogeneous photooxygenation

et al. 2006

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The incorporation of decatungstate in polymeric membranes provides new heterogeneous photocatalysts for the oxidation of organic substrates under oxygen atmosphere at 25°C. Photocatalytic membranes have been prepared yielding polymeric films with a high thermal, chemical and mechanical stability (PVDF, PDMS, Hyflon). Surface spectroscopy techniques including transmittance and reflectance UV-Vis and FT-IR have been used to assess the photocatalyst integrity within the polymeric support. Catalyst screening has been performed under both homogeneous and heterogeneous photooxygenation conditions. The photocatalyst activity has been evaluated in terms of the substrate conversion, turnover numbers, and recycling experiments. A membrane induced selectivity behavior has been evidenced by comparison with homogeneous oxidations.

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Section: Polymeric Membranes Embedding Decatungstatementioning

confidence: 99%

Hybrid photocatalytic membranes embedding decatungstate for heterogeneous photooxygenation

et al. 2006

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“…Uracil molecule, as a part of the RNA helix, is one of the most studied compounds due to its relevance in pharmacy and biochemistry . Consequently, its acidity, basicity solvation by water molecules, its fragmentation in mass spectrometry, and its reactivity with respect to different reactants and metal ions have been investigated. Their tautomeric forms attracted the attention of many scientists along the years as they are suspected to be behind the genetic mutations .…”

Section: Introductionmentioning

confidence: 99%

Effects of the ionization in the tautomerism of uracil: A reaction electronic flux perspective

et al. 2015

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The one-step tautomerization processes of uracil and its radical cation and radical anion have been investigated in the light of the reaction force and reaction electronic flux (REF) formalisms. The relative energies of the different tautomers as well as the corresponding tautomerization barriers have been obtained through the use of the G4 high-level ab initio method and by means of B3LYP/6-311+G(3df,2p)//B3LYP/6-311+G(d, p) calculations. Systematically, the enol radical cations are more stable in relative terms than the neutral, due to the higher ionization energy of the diketo forms with respect to the enolic ones. Conversely, the enol radical anions, with the only exception of the 2-keto-N1 anion, are found to be less stable than the neutral. The effects of the ionization are also sizable on the tautomerization barriers although this effect also depends on the particular tautomerization process. The reaction force analysis shows that all reactions are mainly activated through structural rearrangements that initiate the electronic activity. This electronic activity is monitored along the reaction coordinate through the REF that obeys a delicate balance between the acid and basic character of the atoms involved in the hydrogen transfer.

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“…16,22,23 However, this latter activation mechanism, might be detrimental for the overall selectivity of the process, so that appropriate conditions and/or heterogenization strategies have been adopted. 2,24 In water, the choice of an appropriate hydrophobic support is expected to control the preferential adsorption of apolar substrates, thus increasing their effective concentration, in proximity to the catalyst active sites. 25,26 Moreover, discrimination among the competing reactants and products by the heterogeneous surface is a key factor for the selectivity tuning of the oxidation.…”

Section: Chemical Activationmentioning

confidence: 99%

“…27 The aqueous photooxidation of alcohols by POMs has been initially explored under homogeneous conditions. 24 The results presented in Table 1, refer to both aliphatic and aromatic substrates, including phenol and a target biomolecule like the uracil glycol. This latter undergoes a two-step oxidation to isodialuric acid, and alloxane (Scheme 3).…”

Section: Chemical Activationmentioning

confidence: 99%