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Selective Activation of Benzyl Alcohol Coupled with Photoelectrochemical Water Oxidation via a Radical Relay Strategy
摘要： Selective oxidation to produce target chemicals usually need activation of O2 at high temperature and/or pressure, which have largely restricted its practical operation and application. Here, we put forward a radical-relay strategy coupling photoelectrochemical (PEC) water oxidation towards efficiently selective conversion of benzyl alcohol (BA) to benzaldehyde (BAD). An illuminated BiVO4 (BVO) photoanode covered with an ultrathin (~3 nm) hydrothermally synthesized layered double hydroxide (U-LDH) catalyst and graphene (G) exhibited >99% selectivity to BAD (1.2 V vs. RHE). Mechanistic studies and DFT calculation verified that the hydroxyl radicals (?OH) generated from the oxidation of water are bound to the surface of U-LDH through hydrogen-bonding interactions and the energy is lowered. Fourier transform infrared spectroscopy showed that BA is adsorbed to the U-LDH catalyst, but BAD is not. Thus, the selectivity is not only favored by the controlled oxidation capacity of ?OH radicals, but the desorption of the desired product from the catalyst before further oxidation occurs. This work introduces an alternative PEC way to achieve mild and selective oxidation of BA derivatives based on ternary G@U-LDH@BVO catalysts.
关键词： radical relay,ultrathin LDH,aromatic alcohols,PEC water oxidation,selective activation
更新于2025-09-23 15:21:01
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9-Fluorenone as Photocatalyst for the Oxidation of Alcohols with Air
摘要： Das and co-workers report a visible light-induced oxidation of alcohols by using oxygen or air as oxidant in the presence of 9-fluorenone as organic photocatalyst. The presented methodology is applicable to activated alcohols (benzylic or allylic alcohols), but aliphatic, steroidal, and heterocyclic alcohols can also be used as substrates. Mechanistic studies indicate the presence of peroxide and superoxide radicals as the actual oxidants.
关键词： fluorenone,steroids,reactive oxygen species,alcohols,oxidation
更新于2025-09-23 15:21:01
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Infrared Spectroscopic and Kinetic Characterization on the Photolysis of Nitrite in Alcohol-Containing Aqueous Solutions
摘要： Nitrite is regarded as a potential OH and NO precursor in aqueous solution upon ultraviolet photolysis. A step-scan Fourier-transform interferometer was employed to collect the transient infrared difference spectra upon excitation of the sodium nitrite aqueous solution in the presence of methanol and ethanol upon 355 nm pulsed excitation. The photolytic intermediates were proposed to be NO and NO2 via the direct dissociation from NO2? and the rapid reaction of OH and NO2?, respectively. Coupled with the theoretical calculations of the absolute energies and harmonic wavenumbers of relevant species using B3LYP density functional theory with the C-PCM model to account for the medium effect of H2O, a transient band at 1860?2030 cm?1 could be attributed to dissolved N2O3 isomers that could be quickly generated from NO + NO2. On the basis of the predicted thermodynamics, the reactions of alcohols with N2O3 were less thermodynamically favorable than that of water, resulting in a slightly decelerated depletion rate of N2O3 in alcohol-containing aqueous solution. Comparing the transient population of N2O3 in the absence and presence of CH3OH or C2H5OH, the upper-bound bimolecular rate coefficient of NO or NO2 with alcohols is reported as 7.3 × 103 M?1 s?1 for the first time. The spectroscopic and kinetic evidence of the reactivity of alcohols with NO, NO2, and N2O3 are provided to augment the roles of alcohols and NxOy in solution or in aqueous aerosol photochemistry.
关键词： Alcohols,Kinetics,Nitrite,Infrared spectroscopy,Aqueous solution,Photolysis
更新于2025-09-23 15:19:57
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Application of an electron-transfer catalyst in light-induced aerobic oxidation of alcohols
摘要： The first heterogeneous photocatalysis system including a bipyridinium-based complex as the electron-transfer catalyst was developed for aerobic oxidation of alcohols without the use of any noble-metal, external N-oxide or peroxide co-oxidant. The current work provides an efficient strategy for alcohol oxidation through a cost-effective, convenient and eco-friendly route.
关键词： bipyridinium complex,aerobic oxidation,heterogeneous photocatalysis,alcohols,electron-transfer catalyst
更新于2025-09-19 17:15:36
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Chemoselective photocatalytic oxidation of alcohols to aldehydes and ketones by nitromethane on titanium dioxide under violet 400 nm LED light irradiation
摘要： In this study, for the first time, nitroalkanes especially nitromethane, have been used as an electron acceptor for the highly chemoselective oxidation of alcohols in the presence of TiO2 photocatalyst under 400 nm LED irradiation. The reactions showed excellent selectivity for the production of aldehydes. Interestingly aldehydes such as benzaldehyde and p-methoxybenzaldehyde are stable in the reaction condition. In the case of the use of 2-nitropropane and 2-methyl-2- nitropropane, the product of imine, which is the result of the reaction of aldehyde with aliphatic amine, is also produced.
关键词： chemoselective oxidation,ketones,LED irradiation,aldehydes,nitromethane,TiO2 photocatalyst,nitroalkanes,alcohols
更新于2025-09-19 17:13:59
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Copper‐Phosphine Supported Fe <sub/>3</sub> O <sub/>4</sub> @SiO <sub/>2</sub> as a Novel Reusable Nanocatalyst‐Catalyzed Tandem Reaction of Indole and Alcohols to Bis(indolyl)methanes under Blue LED Light
摘要： Nano Fe3O4@SiO2@TPP(cid:0) Cu as a novel heterogeneous nano-catalyst was prepared and authenticated by usual analytical and spectroscopic techniques. The prepared Fe3O4@SiO2@TPP(cid:0) Cu was applied to preparation of bis(indolyl) methane derivatives via a three-component reaction of aromatic alcohols with indoles under blue led lights. The advantages of this method are the selective oxidation of alcohols under mild conditions. The recycling studies revealed that catalyst could be easily recovered using an external magnet and reused for five times without significant loss of its catalytic activity.
关键词： Nano Fe3O4@SiO2@TPP(cid:0) Cu,Superparamagnetic nanocatalyst,Oxidation alcohols,Blue LED Light,Bis(indolyl)methanes
更新于2025-09-11 14:15:04
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Benzyl Alcohol Oxidation Using Gold Catalysts Derived from Au8 Clusters on TiO2
摘要： Atomically-precise gold clusters have gained attraction in catalysis due to high fraction of low-coordinated gold atoms, unique structural geometry and ligand effect. Phosphine-ligated gold clusters offer an advantage in the light of the labile gold-phosphorous bond for easy ligand removal. Here, heterogeneous gold catalysts were prepared by depositing atomically-precise phosphine-ligated gold clusters, Au8(PPh3)8(NO3)2 onto anatase-phase TiO2 nanoparticles. The catalysts were then calcined under two different conditions: O2 (Au8/TiO2:O2) and O2 followed by H2 (Au8/TiO2:O2–H2) at 200 °C, to dislodge phosphine ligands from the Au core. It was found that Au8/TiO2:O2–H2 catalyst showed a decent catalytic activity in benzyl alcohol oxidation while Au8/TiO2 and Au8/TiO2:O2 were completely inactive. Such results imply that small-size gold clusters (2–3 nm) alone do not always contribute to high catalytic activity of gold catalysts. It is suggested that the presence of NO3 species defines the catalytic activity of supported gold clusters in benzyl alcohol oxidation in the case of these catalysts and reinforces our initial claim in the previous work.
关键词： Heterogeneous catalysis,Oxidation,Alcohols,Green chemistry
更新于2025-09-10 09:29:36
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Degradation of Bromate by Fe(II)-Ti(IV) Layered Double Hydroxides Nanoparticles under Ultraviolet Light
摘要： The photocatalytic decomposition of bromate (BrO3-), a possible human carcinogen, has attracted much attention because of its high efficiency and easier combination with ultraviolet (UV) disinfection in water treatment plants. In this study, the Fe(II)-Ti(IV) layered double hydroxides (LDHs) have been made through a facile hydrothermal method and used as an alternative photocatalyst for reduction of BrO3-. LDHs prepared at a Fe/Ti molar ratio of ~0.5 and pH 7.0, denoted as Fe-Ti-0.5 (pH 7.0), exhibited the highest BrO3- removal efficiency (removal rate constant = 0.067 ± 0.002 min-1) compared to commercial TiO2 and the LDHs prepared at different pHs or different Fe/Ti ratios. The presence of alcohols in water enhanced the photocatalytic reduction of BrO3- due to the greater abundance of electrons caused by alcohols effectively reacting with holes. The neutral pH also favors the degradation of BrO3-. However, the presence of nitrate and nitrite can inhibit the degradation process, due to their reactions with hydrated electrons (eaq-) and hydrogen atom radicals (H·). Cyclic degradation runs and magnetic separation techniques demonstrated the superior reusability of the Fe-Ti-0.5 (pH 7.0) LDH for BrO3- removal. The removal rate of BrO3- under UV was higher than that without UV, indicating that the decomposition proceeded primarily via a photo-reductive mechanism induced by eaq- and H· and thus degradation pathways are proposed. Moreover, when tested in tap water, greater than 90% of BrO3- was removed after 60 min reaction in UV/Fe-Ti-0.5 (pH 7.0) LDH systems in the presence of 5‰ (v/v) methanol. This demonstrates the high potential for such systems for removing BrO3- from disinfected drinking water. This work may shed lights on the design of effective photocatalysts for the enhanced degradation of BrO3- in water plants and the influence of constituents in raw water on the treatment.
关键词： Bromate removal,UV/layered double hydroxides system,Alcohols addition,Reductive species,Tap water
更新于2025-09-09 09:28:46
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Complementarity of Electronic and Vibrational Circular Dichroism Spectroscopy in Structure Determination of Vic-Amino Alcohols
摘要： There is no doubt that determination of the absolute configuration of isolated natural products or synthesized compounds remains one of the most important tasks in all fields of chemistry, biochemistry, structural biology and medicinal chemistry. This is unquestionably due to the fact that biological activity is closely related to the stereostructure of bioactive compounds. Therefore, access to methods allowing simple and primarily unequivocal determination of their absolute configuration (AC) and/or conformation is of particular significance. Such a role is at present fulfilled by chiroptical techniques. In the last two decades chiroptical spectroscopy has been one of the most rapidly developing areas of chiral analysis due to the availability of modern, highly specialized and dedicated to particular chiroptical techniques commercial instruments. Recent progress in ab initio simulations of chiroptical properties has also significantly contributed to the increase of the use of chiroptical spectroscopy as a stereochemistry probe [1]. It is generally accepted that combined experimental and theoretical analysis opens much broader application opportunities for chiroptical spectroscopy by giving theoretical basis to experimental results [1-4]. Moreover, utilization of multiple (at least two) chiroptical techniques increases the confidence level of the stereochemical assignment and is nowadays considered by many authors to be the best practice [1-5]. In this Editorial, we will focus on such a combined experimental and theoretical approach of electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) to determine the absolute configuration and conformation. We intend to demonstrate that both these chiroptical techniques are well cooperating and mutually complementary. Moreover, we want to show that the concerted use of the two methods clearly provides more definitive ACs although in many cases stereochemistry can be determined by using only a single chiroptical property. As a model compound for this study (1S,2R)-2-amino-1,2-diphenylethanol (1) with formula shown here below and representing vic-amino alcohols was chosen (Figure 1).
关键词： Electronic Circular Dichroism,Chiroptical Spectroscopy,Absolute Configuration,Vic-Amino Alcohols,Vibrational Circular Dichroism
更新于2025-09-04 15:30:14