Abstract:Selective oxidation of glycerol to high value-added derivatives is a promising biomass conversion pathway, but the related reaction mechanism, especially the solvent effect, is rarely studied. In this work, O-doped...
“…Table 2 shows results for PyNO deprotection in aqueous suspensions of TiO 2 in the presence of intermediates produced by glycerol oxidation. [31][32][33][34][35] When the intermediates (Entries 2-6) were used, the Py yields were almost the same as the yield in the case of glycerol (Entry 1). The amount of CO 2 produced tended to increase in the following order: glyceraldehyde (Entry 2), 1,3-dihydroxyacetone (Entry 3) and intermediates having a carboxyl group (Entries 4-6).…”
Section: Use Of Possible Intermediates Derived From Glycerolmentioning
Deprotection of pyridine N-oxides under mild conditions with an inexpensive and environmentally friendly reducing reagent is an important chemical procedure. The use of biomass waste as the reducing reagent, water as the solvent and solar light as the energy source is one of the most promising approaches with minimal impact on the environment. Therefore, a TiO 2 photocatalyst and glycerol are suitable components of this type of reaction. Stoichiometric deprotection of pyridine N-oxide (PyNO) with a minimal amount of glycerol (PyNO:glycerol = 7 : 1) was achieved, with only CO 2 being produced as the final oxidation product of glycerol. The deprotection of PyNO was thermally accelerated. Under solar light, the temperature of the reaction system increased to 40-50 °C and PyNO was also quantitatively deprotected, indicating that solar energy, i. e., UV light and thermal energy, can be effectively used. The results provide a new approach in the fields of organic chemistry and medical chemistry using biomass waste and solar light.
“…Table 2 shows results for PyNO deprotection in aqueous suspensions of TiO 2 in the presence of intermediates produced by glycerol oxidation. [31][32][33][34][35] When the intermediates (Entries 2-6) were used, the Py yields were almost the same as the yield in the case of glycerol (Entry 1). The amount of CO 2 produced tended to increase in the following order: glyceraldehyde (Entry 2), 1,3-dihydroxyacetone (Entry 3) and intermediates having a carboxyl group (Entries 4-6).…”
Section: Use Of Possible Intermediates Derived From Glycerolmentioning
Deprotection of pyridine N-oxides under mild conditions with an inexpensive and environmentally friendly reducing reagent is an important chemical procedure. The use of biomass waste as the reducing reagent, water as the solvent and solar light as the energy source is one of the most promising approaches with minimal impact on the environment. Therefore, a TiO 2 photocatalyst and glycerol are suitable components of this type of reaction. Stoichiometric deprotection of pyridine N-oxide (PyNO) with a minimal amount of glycerol (PyNO:glycerol = 7 : 1) was achieved, with only CO 2 being produced as the final oxidation product of glycerol. The deprotection of PyNO was thermally accelerated. Under solar light, the temperature of the reaction system increased to 40-50 °C and PyNO was also quantitatively deprotected, indicating that solar energy, i. e., UV light and thermal energy, can be effectively used. The results provide a new approach in the fields of organic chemistry and medical chemistry using biomass waste and solar light.
“…Active radical capture experiments and EPR investigation established that singlet oxygen and superoxide radicals were the main reactive species in the reaction mechanism. Moreover, it was found that the oxidative esterification reaction can occur to generate new ester compounds in the glycerol acetonitrile solution [ 158 ]. Figure 11.…”
Section: Prominent Catalysis Using Carbon Nitridementioning
confidence: 99%
“… Figure 11. Possible photocatalytic reaction routes for glycerol oxidation over OCNN-2 in water and acetonitrile, reproduced with permission from [ 158 ]. …”
Section: Prominent Catalysis Using Carbon Nitridementioning
Carbon nitrides, a distinguished class of metal-free catalytic materials, have presented a good potential for chemical transformations and are expected to become prominent materials for organocatalysis. This is largely possible due to their low cost, exceptional thermal and chemical stability, non-toxicity, ease of functionalization, porosity development, etc. Especially, the carbon nitrides with increased porosity and nitrogen contents are more versatile than their bulk counterparts for catalysis. These N-rich carbon nitrides are discussed in the earlier parts of the review. Later, the review highlights the role of such carbon nitride materials for the various organic catalytic reactions including Knoevenagel condensation, oxidation, hydrogenation, esterification, transesterification, cycloaddition, and hydrolysis. The recently emerging concepts in carbon nitride-based organocatalysis have been given special attention. In each of the sections, the structure–property relationship of the materials was discussed and related to their catalysis action. Relevant comparisons with other catalytic materials are also discussed to realize their real potential value. The perspective, challenges, and future directions are also discussed. The overall objective of this review is to provide up-to-date information on new developments in carbon nitride-based organic catalysis reactions that could see them rising as prominent catalytic materials in the future.
“…Several graphitic carbon nitrides were also employed as photocatalysts in the transformation of alcohols to aldehydes or ketones. Thus, a carbon-nanodot-doped material derived from 33 [193], a few-layered phosphorene nanostructure graphitic material [194], the basic unmodified graphitic carbon nitride 33 [119,195,196] and several 33 modified by thermal, chemical and mechanical processes [197], with N vacancies [198] and doped with P [199], O [200] and S atoms [201], could successfully catalyze the mentioned reaction under visible light irradiation. The photocatalysts were able to be reused after centrifugation or filtration without decreasing their catalytical activity.…”
Section: Heterogeneous Oxidative Dehydrogenation Of C-o Bondmentioning
Performing synthetic transformation using visible light as energy source, in the presence of a photocatalyst as a promoter, is currently of high interest, and oxidation reactions carried out under these conditions using oxygen as the final oxidant are particularly convenient from an environmental point of view. This review summarizes the recent developments achieved in the oxidative dehydrogenation of C–N and C–O bonds, leading to C=N and C=O bonds, respectively, using air or pure oxygen as oxidant and metal-free homogeneous or recyclable heterogeneous photocatalysts under visible light irradiation.
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