Aqueous Peroxide Research Articles

Hydrogen Peroxide-Treated Carbon Dot Phosphor with a Bathochromic-Shifted, Aggregation-Enhanced Emission for Light-Emitting Devices and Visible Light Communication.

It is demonstrated that treatment of blue‐emissive carbon dots (CDs) with aqueous hydrogen peroxide (H2O2) results in the green emissive solid state CD phosphor with photoluminescence quantum yield of 25% and short luminescence lifetime of 6 ns. The bathochromic‐shifted, enhanced green emission of H2O2‐treated CDs in the powder is ascribed to surface state changes occurring in the aggregated material. Using the green emissive H2O2‐treated CD phosphor, down‐conversion white‐light‐emitting devices with cool, pure, and warm white light are fabricated. Moreover, using the green emissive CD phosphor as a color converter, a laser‐based white‐light source is realized, and visible light communication with a high modulation bandwidth of up to 285 MHz and data transmission rate of ≈435 Mbps is demonstrated.

On the redox nature of ceria-zirconia mixed nanocatalysts and its effect on catalytic wet peroxide oxidation of chlorinated organic pollutants

The potential application of ZrxCe1-xO2 (x: 1, 0.75, 0.5, 0.25, 0) nanocomposites in the oxidation of chlorinated phenolic compounds was studied with respect to Catalytic Wet Peroxide oxidation of 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP) and 2,4-dichlorophenoxy acetic acid (2,4-D) was experimented in presence of aqueous hydrogen peroxide as oxidant. Zirconium doping on nanoceria lattice increased its catalytic activity towards Wet Peroxide Oxidation of the target pollutants. 4-CP (500 mg/L) was degraded with 14.9% TOC and 45.8% COD removal after 75 min at 70 °C using Zr0.75Ce0.25O2 catalyst. 2,4-DCP (250 mg/L) conversion with 22.5% TOC and 52.8% COD removal was observed at 75 min over Zr0.5Ce0.5O2 catalyst. 100% catalytic oxidative conversion of 2,4-D (250 mg/L) with 23.68% Total Organic Carbon (TOC) and 47.80% Chemical Oxygen Demand (COD) removal was achieved at 70 °C at 90 min. Temperature Programmed Reduction (TPR) analysis indicated that the reducing capacity of ceria increased on zirconium doping. The catalysts were stable and reusable upto six successive runs as demonstrated by X-ray diffraction (XRD) and surface area measurements.

Greening Oxidation Catalysis: Iron Catalyzed Alkene syn-Dihydroxylation with Aqueous Hydrogen Peroxide in Green Solvents

Herein, we disclose the application of green solvents in a biologically inspired oxidation reaction. In a mixture of propylene carbonate and ethyl acetate, iron catalyzed syn-dihydroxylation of olefins with aqueous hydrogen peroxide proceeds in short reaction times with excellent yields and chemoselectivity. The current report showcases the suitability of this sustainable media to this class of important reactions.

Two inorganic–organic hybrids based on a polyoxometalate: Structures, characterizations, and epoxidation of olefins

Two new inorganic–organic hybrids, [Co3(bpdo)6(H2O)4Cl2][SiW12O40]·H2O (Co-SiW) and [Ni3(bpdo)6(H2O)4Cl2][SiW12O40]·H2O (Ni-SiW) (bpdo = 4,4′-bis(pyridine-N-oxide)), were synthesized from the Keggin-type [SiW12O40] anion and Co(II) and Ni(II) under hydrothermal conditions, respectively, and characterized by elemental analyses, powder XRD, IR spectra, and single-crystal X-ray diffraction. The structural analysis indicates that the 1D chain is constructed from a POM-based half-cage as a secondary building block linked by bridging bpdo ligands. The zigzag chains further stack into a three-dimensional body with channels. The 3D network structure with amphiphilic cavities is shaped by electrostatic interactions through the planes, which has potential to allow molecules such as styrene and H2O2 ingress and egress. Both of the hybrids demonstrated catalytic activity for epoxidation of olefins, which was examined using styrene and aqueous hydrogen peroxide (30%) as oxidant in acetonitrile, along with Co-SiW and Ni-SiW in a heterogeneous manner at 60 °C. Moreover, the conversion of epoxidation reaction in a heterogeneous manner is close to that of homogeneous catalysis, while being conveniently recovered and steadily reused without change of catalyst structure after epoxidation reactions.

Enhanced mid-infrared multi-bounce ATR spectroscopy for online detection of hydrogen peroxide using a supercontinuum laser

A compact multi-bounce attenuated total reflection (ATR) probe combined with a Fabry-Pérot filter spectrometer (FPFS) has been developed for detection of hydrogen peroxide used for oxidative gas scrubbing operating in the mid-infrared (MIR) spectral region. A novel MIR supercontinuum light source is employed to enhance the quantification capabilities of the sensor and is compared to a classical thermal emitter. An improvement of a factor of 4 in noise and approximately a factor of 3 in limit of detection is shown in this study allowing fast inline detection of aqueous hydrogen peroxide solutions around 0.1%.

Effect of Ti Speciation on Catalytic Performance of TS-1 in the Hydrogen Peroxide to Propylene Oxide Reaction

Hydrogen peroxide to propylene oxide (HPPO) reaction is an attractive process exploiting titanium silicalite-1 (TS-1) as a catalyst in combination with aqueous hydrogen peroxide as an oxidizing agent. Beyond the industrial interest, TS-1 represents one of the most widely characterized catalysts due to its unique properties. However, a unified description on the speciation of the different Ti species and their correlation to catalytic performances is missing in the literature. This work aims to exploit spectroscopic techniques (namely, diffuse reflectance UV–vis, Raman, FT-IR, and Ti K-edge XANES) in a qualitative and quantitative way to thoroughly characterize Ti sites in a selected set of industrially relevant TS-1 samples, each one owning a peculiar Ti speciation. The outcomes of this study have been then related to the activity of each catalyst in HPPO reaction, showing its linear correlation with the content of perfect Ti sites (i.e., isomorphously substituting Si in the zeolitic framework). Other Ti ...

Synthesis and characteristics of Mg‐Ni‐Al‐CO3 hydrotalcites for styrene oxidation

AbstractMg‐Ni‐Al‐CO3 hydrotalcite‐like material was synthesized by coprecipitation method at a certain pH. The synthesized solids have been characterized by physical techniques, namely XRD, IR, TEM, and EDS. All synthesized samples showed a well‐defined hydrotalcite structure with the presence of nickel(II) ions in Mg‐Al hydroxide lattice. The Mg‐Ni‐Al‐CO3 catalyst has been tested for the oxidation of styrene with aqueous hydrogen peroxide solution and showed a good catalytic activity in the formation of benzaldehyde. Styrene conversion is in the range of 20‐85 % with the high selectivity to benzaldehyde at 50‐80°C, 4 hours.

Insights into the direct selective oxidation of methane to methanol over ZSM-5 zeolytes in aqueous hydrogen peroxide

Abstract The direct selective oxidation of methane by aqueous hydrogen peroxide over ZSM-5(50) has been investigated. Methyl hydroperoxide was confirmed as the initial product of methane oxidation. The decomposition of methyl hydroperoxide to formaldehyde is established as a key intermediate in an oxidation pathway to formic acid and ultimately CO2. Hydrogen was detected during the oxidation of methane over ZSM-5 zeolites. The hydrogen was evaluated in terms of its origins and possible role in the production of MeOH. The addition of a copper salt to the ZSM-5(50) zeolite was found to decrease the overall productivity of all methane oxygenates. The use of copper also promoted the selectivity for methyl hydroperoxide whilst removing formic acid. The role of hydroxymethyl-methyl hydroperoxide is considered as an intermediate in the decomposition of methyl hydroperoxide to methanol. A tentative proposal into the nature of the iron species responsible for the catalytic species in ZSM-5(50) is made.

Catalytic performance of binary and ternary oxovanadium complexes of dipyridinyl-urea in (ep)oxidation of cis-cyclooctene and 1-octene

Two novel ternary and binary mono-oxovanadium(IV) complexes of acetylacetonate (ac) and 1,3-dipyridin-2-yl-urea are synthesized, as VO(acac)(L) (1:1) and VO(L)2 (1:2). They are characterized by various physico-chemical spectroscopic tools. The formation constants Kf are calculated from the spectrophotometric measurements. The catalytic potential of VO(acac)(L) and VO(L)2 has been examined in the (ep)oxidation of alkenes (cis-cyclooctene and 1-octene) by an aqueous hydrogen peroxide, H2O2, and tert-butyl hydroperoxide, TBHP. The effects of temperature, solvent and oxidant/alkene molar ratio are studied in order to get the optimized reaction conditions. Most of the catalytic (ep)oxidation products of cis-cyclooctene and 1-octene are determined qualitatively and quantitatively using gas chromatographic analysis. The increase of the catalyst amount to double time reduces the (ep)oxidation process time with improvement of the amount of the chemoselective epoxy product.

Oxygenation of sulfides catalysed by SBA‐15‐immobilized molybdenum(VI) complex of a bis(phenol) diamine ligand using aqueous hydrogen peroxide as a green oxidant

A highly efficient and reusable molybdenum‐based catalyst has been synthesized by covalent grafting of a bis(phenol) diamine ligand, namely 2‐(((2‐bromoethyl)(2‐((3,5‐di‐tert‐butyl‐2‐hydroxybenzyl)amino)ethyl)amino)methyl)‐4,6‐di‐tert‐butylphenol, onto functionalized ordered mesoporous silica (SBA‐15) followed by complexation with MoO2(acac)2. The resulting organic–inorganic hybrid material was found to be a highly effective catalyst for oxygenation of various sulfides to their corresponding sulfoxides or sulfones. The catalyst was characterized using transmission and scanning electron microscopies, X‐ray photoelectron, Fourier transform infrared and atomic absorption spectroscopies, Brunauer–Emmett–Teller surface area analysis and thermogravimetric analysis. Mild reaction conditions, high selectivity and easy recovery and reusability of the catalyst render the presented protocol very useful for addressing industrial needs and environmental concerns.

Mn(III) and Mn(II) complexes of tridentate Schiff base ligands; synthesis, characterization, structure, electrochemistry and catalytic activity

Abstract Three Mn(III) complexes [Mn(L1)2] (ClO4) 1, [Mn(L2)2] (ClO4) 2, [Mn(L3)2] (ClO4) 3, and one Mn(II) complex [Mn(L4)2] 4 were studied for their efficiency as catalysts for epoxidation of olefins with H2O2 at room temperature and 0 °C in the presence of ammonium acetate-acetic acid or triethylamine-perchloric acid system as co-catalyst/buffer. The complexes were obtained from the reaction of Mn(ClO4)2.6H20 with NNO tridentate Schiff base ligands HL1-HL4 synthesized from the condensation reaction of 2-(2-aminoethyl)pyridine and 2-hydroxybenzaldehyde (HL1), 5-chloro-2-hydroxybenzaldehyde (HL2), 5-methoxy-2-hydroxybenzaldehyde (HL3), or 5-nitro-2-hydroxybenzaldehyde (HL4) respectively. The complexes were characterized by spectroscopic techniques as well as by single crystal X-ray diffraction analysis. Electronic effect of the substituents on epoxide yield was also investigated. The crystal structures of complexes confirm coordination of the manganese ion to the ligands through the NNO atoms of the ligands. The spectral changes observed as a function of time for the reaction of the complexes with aqueous (30%) hydrogen peroxide indicates possible formation of an intermediate product; hydroperoxo-complex implicated in the epoxidation reaction. The complexes catalyzed epoxidation of cyclohexene with low yield at room temperature but higher yield at 0 °C in the order complex 3 lower than 1, 1 lower than 2, with the Mn(II) complex 4 recording highest epoxide yield of 9% with turnover of 2.25 at room temperature and yield of 58% with turnover of 14.5 at 0 °C in the presence of ammonium acetate-acetic acid system/ buffer. With the triethylamine-perchloric acid system/buffer, epoxide yield of 46% and turnover of 11.5 was recorded at room temperature while 44% with turnover of 11.0 was obtained at 0 °C for complex 4.

Highly Efficient Catalysts Based on Divanadium-Substituted Polyoxometalate and N-Doped Carbon Nanotubes for Selective Oxidation of Alkylphenols

Alkyl-substituted benzoquinones serve as versatile building blocks for a variety of biologically active compounds. In this work, we present an approach for the environmentally benign synthesis of alkyl-p-benzoquinones, in particular trimethyl-p-benzoquinone (TMBQ, vitamin E precursor), which employs aqueous hydrogen peroxide as oxidant and a divanadium-substituted γ-Keggin polyoxotungstate, [γ-PW10O38V2(μ-O)(μ–OH)]4– (V2-POM), immobilized on nitrogen-doped carbon nanotubes (N-CNTs) as heterogeneous catalyst. A series of supported catalysts V2-POM/N-CNTs containing 5–25 wt % of V2-POM and 0–4.8 atom % of N has been prepared and characterized by elemental analysis, N2 adsorption, SEM, TEM, XPS, and FTIR techniques. The catalytic performance of V2-POM/N-CNTs was assessed in the selective oxidation of 2,3,6-trimethylphenol (TMP) with H2O2 under mild reaction conditions (60 °C, MeCN). The presence of nitrogen in the support ensures strong adsorption and molecular dispersion of V2-POM on the carbon surface, lea...

Lipase-Induced Oxidative Furan Rearrangements

Lipase B from Candida antarctica catalyzes the oxidative ring expansion of furfuryl alcohols using aqueous hydrogen peroxide to yield functionalized pyranones under mild conditions. The method further allows for the preparation of corresponding piperidinone derivatives by enzymatic rearrangement of N-protected furfurylamines.

Surface-Active Hollow Titanosilicate Particles as a Pickering Interfacial Catalyst for Liquid-Phase Alkene Epoxidation Reactions

The design of catalyst particles bearing excellent catalytic activity and suitable surface wettability is the key to successful application of Pickering interfacial catalysis. In this study, the epoxidation of 1-hexene and cyclohexene with aqueous hydrogen peroxide over hollow TS-1 (HTS-1) zeolite was studied as a probe reaction to investigate the influence of catalyst surface wettability on catalytic activity. Hydrophobized HTS-1 particles were fabricated via a postsynthesis desilication treatment with tetrapropylammonium hydroxide and a postsynthesis silylation treatment with hexamethyldisiloxane (HMDSO). The successful preparation of HTS-1 particles was verified by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. X-ray diffraction patterns and ultraviolet-visible spectra confirmed that the hydrophobic modification had no effect on the zeolite structure of HTS-1 particles. Stable Pickering emulsions of aqueous hydrogen peroxide in either 1-hexene or cyclohexene could be prepared using HTS-1 particles as emulsifiers and confirmed by cryo-SEM images. The catalytic behavior in the obtained Pickering emulsions revealed a parabolic distribution of turnover frequency values with respect to the hydrophobization degrees with 0.2-HMDSO/HTS-1 particles possessing the maximum values of 20.6 h-1 for 1-hexene epoxidation and 8.1 h-1 for cyclohexene epoxidation. In addition, these 0.2-HMDSO/HTS-1 particles showed good reusability for more than five cycles.

One-pot synthesis of ethylene glycol by oxidative hydration of ethylene with hydrogen peroxide over titanosilicate catalysts

The oxidative hydration of ethylene with aqueous hydrogen peroxide was investigated over various titanosilicate catalysts for the purpose of one-pot synthesis of ethylene glycol (EG). The effect of titanosilicate topology (Ti-MWW, TS-1, Ti-MCM-68 and Ti-MOR), solvent, Ti content, catalyst amount, H2O/H2O2 ratio, reaction temperature and time on the EG production have been studied in detail. The Ti-MWW/H2O2/H2O catalytic system showed the highest EG yield together with high H2O2 conversion and utilization efficiency for the oxidative hydration of ethylene. The mechanism for the titanosilicate-catalyzed hydration of ethylene oxide (EO) has also been considered, which then shed light on the active sites for the second step in the oxidative hydration of ethylene. The catalyst deactivation could be ascribed to that the target product of EG and other heavy by-products with high boiling points were deposited inside the channels. The used Ti-MWW can be reusable when subjected to the regeneration by high-temperature calcination. Amine-assisted structural rearrangement of Ti-MWW not only enhanced the catalytic activity but also improved its stability in the oxidative hydration of ethylene.

Impact of gold-1-decanethiol-SAM formation and removal cycles on the surface properties of polycrystalline gold and SAM quality

The impact of 1-decanethiol self-assembled monolayer (SAM) formation and removal cycles on polycrystalline Au surfaces and SAM quality was studied with the help of CV, DPV, Pb-UPD, STM, and AFM. The SAM removal was accomplished by dissolution with oxygen radicals generated by UV photolysis of aqueous hydrogen peroxide. During the first Au-SAM formation and removal cycles, the surface roughness decreased. After that, the surface properties remained almost unaffected, indicating that the cyclic treatment removed the most reactive gold surface sites, until a rather stable surface resulted, which guaranteed highly reproducible SAM formation.

Chemoselective Aliphatic C-H Bond Oxidation Enabled by Polarity Reversal.

Methods for selective oxidation of aliphatic C–H bonds are called on to revolutionize organic synthesis by providing novel and more efficient paths. Realization of this goal requires the discovery of mechanisms that can alter in a predictable manner the innate reactivity of these bonds. Ideally, these mechanisms need to make oxidation of aliphatic C–H bonds, which are recognized as relatively inert, compatible with the presence of electron rich functional groups that are highly susceptible to oxidation. Furthermore, predictable modification of the relative reactivity of different C–H bonds within a molecule would enable rapid diversification of the resulting oxidation products. Herein we show that by engaging in hydrogen bonding, fluorinated alcohols exert a polarity reversal on electron rich functional groups, directing iron and manganese catalyzed oxidation toward a priori stronger and unactivated C–H bonds. As a result, selective hydroxylation of methylenic sites in hydrocarbons and remote aliphatic C–H oxidation of otherwise sensitive alcohol, ether, amide, and amine substrates is achieved employing aqueous hydrogen peroxide as oxidant. Oxidations occur in a predictable manner, with outstanding levels of product chemoselectivity, preserving the first-formed hydroxylation product, thus representing an extremely valuable tool for synthetic planning and development.

Oxidative alteration of ferrous smectites and implications for the redox evolution of early Mars.

Surface conditions on early Mars were likely anoxic, similar to early Earth, but the timing of the evolution to oxic conditions characteristic of contemporary Mars is unresolved. Ferrous trioctahedral smectites are the thermodynamically predicted products of anoxic basalt weathering, but orbital analyses of Noachian-aged terrains find primarily Fe3+-bearing clay minerals. Rover-based detection of Fe2+-bearing trioctahedral smectites at Gale Crater suggest that ferrous smectites are the unoxidized progenitors of orbitally-detected ferric smectites. To assess this pathway, we conducted ambient-temperature oxidative alteration experiments on four synthetic ferrous smectites having molar Fe/(Mg+Fe) from 1.00 to 0.33. Smectite suspension in air-saturated solutions produced incomplete oxidation (24-38% Fe3+/ΣFe). Additional smectite oxidation occurred upon re-exposure to air-saturated solutions after anoxic hydrothermal recrystallization, which accelerated cation and charge redistribution in the octahedral sheet. Oxidation was accompanied by contraction of the octahedral sheet (d(060) decreased from 1.53-1.56 Å to 1.52 Å), consistent with a shift towards dioctahedral structure. Ferrous smectite oxidation by aqueous hydrogen peroxide solutions resulted in nearly complete Fe2+ oxidation but also led to partial Fe3+ ejection from the structure, producing nanoparticulate hematite. Reflectance spectra of oxidized smectites were characterized by (Fe3+,Mg)2-OH bands at 2.28-2.30 μm, consistent with oxidative formation of dioctahedral nontronite. Accordingly, ferrous smectites are plausible precursors to observed ferric smectites on Mars, and their presence in late-Noachian sedimentary units suggests that anoxic conditions may have persisted on Mars beyond the Noachian.

Understanding the Regioselectivity of Aromatic Hydroxylation over Divanadium-Substituted γ-Keggin Polyoxotungstate

The aromatic hydroxylation of pseudocumene (PC) with aqueous hydrogen peroxide catalyzed by the divanadium-substituted γ-Keggin polyoxotungstate TBA4[γ-PW10O38V2(μ-O)(μ-OH)] (TBA-1H, TBA = tetrabutylammonium) has been studied using kinetic modeling and DFT calculations. This reaction features high chemoselectivity and unusual regioselectivity, affording 2,4,5-trimethylphenol (TMP) as the main product. Then the computational study was extended to the analysis of the regioselectivity for other alkoxy- and alkylarene substrates. The protonation/deprotonation of TBA-1H in MeCN/tBuOH (1:1) was investigated by 31P NMR spectroscopy. Forms with different protonation states, [γ-PV2W10O40]5– (1), [γ-HPV2W10O40]4– (1H), and [γ-H2PV2W10O40]3– (1H2), have been identified, and the protonation equilibrium constants were estimated on the basis of the 31P NMR data. DFT calculations were used to investigate the oxygen transfer process from hydroperoxo species, [γ-PW10O38V2(μ-O)(μ-OOH)]4– (2) and [γ-PW10O38V2(μ-OH)(μ-OOH)]3...

Oxidative degradation of the extraction residue from a sawdust

The extraction residue (ER) from a sawdust was oxidatively degraded with aqueous hydrogen peroxide (AHPO)/acetic anhydride (AAH) under mild conditions. About 16.1% of organic matter in the ER was converted to soluble portion (SP). In total, 76 compounds were detected in the SP from the reaction mixture by two-dimensional gas chromatography/time of flight-mass spectrometry. They can be classified into 20 group components. Among them, carboxylic acids (CAs) are the most abundant, accounting for ca. 57.2%. Most of the CAs are non-aromatic ones, especially non-aromatic dicarboxylic acids. All the esters produced from the ER degradation are acetates and diacetates. The results suggest that molecular composition of macromolecular species in the sawdust is complicated and the species without highly condensed aromatic rings tend to be oxidatively degraded to soluble compounds with AHPO/AAH. In addition, CH3COO from AAH decomposition involved in the oxidative degradation of the sawdust.