Oxygen Atom Transfer in the Photocatalytic Oxidation of Alcohols by TiO<sub>2</sub>: Oxygen Isotope Studies

Zhang, Miao; Wang, Qi; Chen, Chuncheng; Zang, Ling; Ma, Wanhong; Zhao, Jincai

doi:10.1002/anie.200900322

Cited by 286 publications

(271 citation statements)

References 28 publications

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“…Reaction [7] Selective oxidation of alcohols to carbonyls is a fundamental and significant transformation for the large-scale production of fine chemicals [8,9]. Several UV and visible light driven photocatalytic systems for alcohols oxidation have been developed, such as Ru-(bipy) 3 2+ and its derivatives, TiO 2 or TiO 2 -based materials (dye/TiO 2 ), Pd@CeO 2 , and mesoporous carbon nitride (mpg-C 3 N 4 ) [9][10][11][12][13][14][15][16][17][18].…”

Section: Photoctalytic Activity For Selective Oxidationmentioning

confidence: 99%

Catalytic Applications of Carbon Dots

Kang

Liu

2016

Carbon Nanostructures

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Carbon materials have been used for a long time in heterogeneous catalysis, which can satisfy most of the desirable properties required for a suitable catalyst support. Based on their significant advantages, such as low cost, huge amount, easy accessibility, high surface area, diverse porous structure, and resistance to acidic or basic environments, the carbon nanostructures are hungered for using as proper catalysts directly. Carbon dots (CDs), a new class of carbon nanomaterials with sizes below 10 nm, were also demonstrated to be efficient catalysts, such as, photocatalysts for selective oxidation, light-driven acid-catalysis and hydrogen bond catalysis. In this chapter, we will highlight the preparative methods, which have been used successfully to produce active, selective and durable CDs catalysts and look at their properties and the reactions which they promote. We then consider the catalysts design based on these new CDs and look into the future.

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Section: Photoctalytic Activity For Selective Oxidationmentioning

confidence: 99%

Catalytic Applications of Carbon Dots

Kang

Liu

2016

Carbon Nanostructures

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“…In order to exploit the applicability of the present catalytic system and to generalize the scope of the oxidation process, the oxidation reaction has extended to various types of alcohol such as primary aromatic, allylic, heteroaromatic, and aliphatic alcohols. Generally, all primary aromatic alcohols could be oxidized rapidly to the corresponding aldehydes with complete conversions within very short reaction times (Table 6, entries [10][11][12][13][14][15][16][17][18][19][20][21][22]. Moreover, more than 99% selectivity to corresponding aldehydes has been achieved in most of oxidation reactions and no other products were detected in the reaction mixture because no overoxidation to carboxylic acids occurred.…”

Section: Oxidation Of Different Types Of Alcohols Over 1%mentioning

confidence: 97%

“…The oxidation products such as aldehyde and ketone derivatives are important precursors and intermediates in the cosmetics, perfumery, flame-retardants, insecticides, confectionary, biofuels, and pharmaceutical industries [7][8][9][10][11]. Usually, conventional oxidation of alcohols was conducted using toxic and expensive stoichiometric oxidizing agents such as CrO 3 , KMnO 4 , NaClO, Na 2 Cr 2 O 7 , SeO 2 , and Br 2 and leads to producing harmful by-products [12,13].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO₃, –MnO₂, and –Mn₂O₃ Nanocomposites for Aerial Oxidation of Alcohols

Assal

Kuniyil

Shaik

et al. 2017

Journal of Chemistry

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Zinc oxide nanoparticles doped manganese carbonate catalysts [ % ZnO x -MnCO 3 ] (where = 0-7) were prepared via a facile and straightforward coprecipitation procedure, which upon different calcination treatments yields different manganese oxides, that is, [ % ZnO x -MnO 2 ] and [ % ZnO x -Mn 2 O 3 ]. A comparative catalytic study was conducted to evaluate the catalytic efficiency between carbonates and oxides for the selective oxidation of secondary alcohols to corresponding ketones using molecular oxygen as a green oxidizing agent without using any additives or bases. The prepared catalysts were characterized by different techniques such as SEM, EDX, XRD, TEM, TGA, BET, and FTIR spectroscopy. The 1% ZnO x -MnCO 3 calcined at 300 ∘ C exhibited the best catalytic performance and possessed highest surface area, suggesting that the calcination temperature and surface area play a significant role in the alcohol oxidation. The 1% ZnO x -MnCO 3 catalyst exhibited superior catalytic performance and selectivity in the aerial oxidation of 1-phenylethanol, where 100% alcohol conversion and more than 99% product selectivity were obtained in only 5 min with superior specific activity (48 mmol⋅g −1 ⋅h −1 ) and 390.6 turnover frequency (TOF). The specific activity obtained is the highest so far (to the best of our knowledge) compared to the catalysts already reported in the literatures used for the oxidation of 1-phenylethanol. It was found that ZnO x nanoparticles play an essential role in enhancing the catalytic efficiency for the selective oxidation of alcohols. The scope of the oxidation process is extended to different types of alcohols. A variety of primary, benzylic, aliphatic, allylic, and heteroaromatic alcohols were selectively oxidized into their corresponding carbonyls with 100% convertibility without overoxidation to the carboxylic acids under base-free conditions.

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“…The carbon radicals prefer to combinew ith dioxygen and photogenerated electrons to accomplish the conversion process ( Figure S21). [32] Basically,i tis aw ell-accepted fact that the photocatalytic activity of semiconductors is greatlyr elatedt os everal factors such as electronic structure, surface area, crystal structure, and crystallinity. [33,34] Given that the initial step of the photocatalytic conversion of benzyl alcohol to benzaldehyde involves adsorption of the benzylalcohol molecules, the surface area is considered an important factor for high photocatalytic activity.A much highers pecific surfacea rea gives birth to more active sites, which contributes to better photocatalytic properties.…”

mentioning

confidence: 99%

Achieving Exceptional Photocatalytic Activity and Selectivity through a Well‐Controlled Short‐Ordered Structure: A Case Study of Na_xTaO_y⋅n H₂O

Lang

et al. 2015

ChemCatChem

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The presentw ork reports the preparationo fashort-ordered Na x Ta O y ·n H 2 Oc atalystt hat exhibitse xceptional and highly efficient photocatalytic reactivity towarda erobic oxidation relative to its crystalline counterpart. Synchrotron radiation wide-angle X-ray scattering and transmissione lectron microscopy results indicated that the as-synthesized catalysts hows short-ordered features with well-controlled short-range ordering limits and defect chemistry.T he short-ordered structure of Na x Ta O y ·n H 2 O predicted large amountso fd efective centers and high surface areas that may playc ritical roles in visible-light harvesting and photocatalytic aerobic oxidation. This work may provide an ovel strategy for the development of short-ordered catalytic systemsw ith well-controlled defectc hemistry that exhibit highly efficient photocatalytic properties.In view of future environmentala nd energyc oncerns,c hemical conversionsi ncluding organic synthesis, water splitting, and degradation of pollutants through photocatalytic processes utilizing solar energy are regardeda sp romising. [1,2] Particularly, selectivea erobic oxidation to carbonyl compounds triggered by solar energy has attracted enormous interest, because it uses O 2 as the oxidizing agent in lieu of expensive, toxic, and corrosiveo xidants.[3] Although selectivea erobic oxidation with O 2 can be achievedb yu sing noblem etal catalysts and/or transition-metal complexes, [4,5] photocatalytic processes show advantageso ver noblem etal/complex catalytic systemso wing to their environmentally benign properties and the benefit of using solar energy as am otivating force. Several substrates (e.g.,a lcohols and amines)c an be successfully oxidized by photocatalysts under UV/visible-light irradiation, but low catalytic activity in the visible region is still ac ritical issue.For visible-light harvesting purposes, great efforts have been dedicated to regulating the electronic structure, crystallinity, and lattice structure of these materials, as these properties often have ag reat impact on photocatalytic activity.F or instance,d isordered semiconductors give rise to defective midgaps tates, and this leads to continuous band-gap narrowing and remarkable separation of the geminate photocarrier pair, [6] whicha re vital to concerted catalysis of electron/hole pairs in aerobic oxidation to ensure high selectivity.[3] Basically, higher crystallinity and less structural disordering lead to higher photocatalytic activity. [7,8] Nevertheless, recent studies indicatet hat short-ordered semiconductors, especially amorphouss emiconductors, can also give superior photocatalytic activity. [9,10] For instance, amorphous TiO 2 and NaTaO x werer eported to show higherp hotocatalytic activityf or dye degradation and water splitting than their crystalline counterparts. [11,12] From the viewpoint of unprecedented practical applications, as ystemic identification of disordered semiconductors and their photocatalytic behavior is stilln ecessary,b ecause it is advantageousf or th...

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Oxygen Atom Transfer in the Photocatalytic Oxidation of Alcohols by TiO₂: Oxygen Isotope Studies

Abstract: An uninvited guest: In the photocatalytic oxidation of alcohols to their corresponding aldehydes or ketones using TiO2 in organic solvents, such as benzotrifluoride (BTF), an oxygen atom transfer from the dioxygen to the α‐carbon atom of the alcohol dominates the reaction process.

Cited by 286 publications

References 28 publications

Catalytic Applications of Carbon Dots

Catalytic Applications of Carbon Dots

Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO₃, –MnO₂, and –Mn₂O₃ Nanocomposites for Aerial Oxidation of Alcohols

Achieving Exceptional Photocatalytic Activity and Selectivity through a Well‐Controlled Short‐Ordered Structure: A Case Study of Na_xTaO_y⋅n H₂O

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Oxygen Atom Transfer in the Photocatalytic Oxidation of Alcohols by TiO2: Oxygen Isotope Studies

Abstract: An uninvited guest: In the photocatalytic oxidation of alcohols to their corresponding aldehydes or ketones using TiO2 in organic solvents, such as benzotrifluoride (BTF), an oxygen atom transfer from the dioxygen to the α‐carbon atom of the alcohol dominates the reaction process.

Cited by 286 publications

References 28 publications

Catalytic Applications of Carbon Dots

Catalytic Applications of Carbon Dots

Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO3, –MnO2, and –Mn2O3 Nanocomposites for Aerial Oxidation of Alcohols

Achieving Exceptional Photocatalytic Activity and Selectivity through a Well‐Controlled Short‐Ordered Structure: A Case Study of NaxTaOy⋅n H2O

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Oxygen Atom Transfer in the Photocatalytic Oxidation of Alcohols by TiO₂: Oxygen Isotope Studies

Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO₃, –MnO₂, and –Mn₂O₃ Nanocomposites for Aerial Oxidation of Alcohols

Achieving Exceptional Photocatalytic Activity and Selectivity through a Well‐Controlled Short‐Ordered Structure: A Case Study of Na_xTaO_y⋅n H₂O