Reagent For Oxidation Research Articles

Efficient oxidation of arylmethylene compounds using nano-MnO2

Nano-MnO2 has been developed as an efficient and mild reagent for the high-yield oxidation of arylmethylene compounds to the corresponding aldehydes and ketones as well as benzylic ethers to esters. The reagent is conveniently prepared and shows reactivity superior to synthetic (Attenburrow) MnO2 and commercial MnO2 under both microwave and conventional conditions. Typical reactions are performed using 25wt% of nano-MnO2 relative to the substrate, and the reagent can be recycled up to six times without significant loss of activity. The observed conversions correlate well with surface-water content in the different MnO2 samples, as determined by thermogravimetric analysis.

ChemInform Abstract: Manganese Dioxide Supported on Aluminum Silicate: A New Reagent for Oxidation of Alcohols under Heterogeneous Conditions.

AbstractManganese dioxide supported on aluminum silicate selectively oxidizes both benzylic alcohols and cinnamyl alcohol to the corresponding aldehydes and ketones, respectively.

Oxidant-induced intramolecular triazole formation

C3-symmetric ligands carrying a rigid triaminoguanidinium backbone are important building blocks for the preparation of supramolecular coordination cages as tetrahedra or trigonal bipyramides. Coordination of Eu(III)- or Gd(III)-ions leads to 1,2,4-triazole formation, which has been reported only rarely. Using Pd(II)-complexes as a model system, this triazole formation could be analyzed in more detail. The preparation of Pd(II)-coordination compounds can be easily done under stoichiometric control. These complexes could be transformed into 1,2,4-triazoles using O2 or H2O2 as an oxidation reagent. The steric demand of the PR3-coligand seems to play a key role in the cyclisation reaction.

Optimization of Biological Oxygen Demand Reduction from Textile Effluent by Oxidation

The textile dyeing and printing units in Sanganer town, Jaipur, Rajasthan, India. Discharge a huge volume of mostly untreated textile dye wastewater (10,000-15,000kl/day) into various pools and drain adjoining the textile printing units. A number of azo dyes are used in textile printing industries, As a result. The textile waste waters are loaded with them, along with other chemicals used during printing and fixing of dyes on cloth. The main cause of generation of this effluent is the use of huge volume of water either in the actual chemical processing or during re-processing in preparatory, dying, printing and finishing, which is responsible for higher biological oxygen demand(BOD), so currently these industries facing significant challenges, associated mainly with Environmental legislation because BOD removal reduction of could not be achieved, discharge effluent's concentration is too high from discharge limit prescribed by Rajasthan State Pollution Control Board, The objective of study is physiochemical analysis of water in study area and the BOD reduction in textile wastewater. For BOD reduction three oxidizers Hydrogen peroxide, Calcium hypochlorite, Potassium dichromate was used to compare their treatment efficiency at different temperature, dosages and retention time. Keywords: Textile industry, Textile effluent, BOD reduction, Oxidizing reagents, Discharge limit.

Polymer-supported dichloroiodate as a new polymeric oxidation reagent for novel and selective oxidation of benzylic alcohols under mild aprotic conditions

Article history: Received March 27, 2013 Received in Revised form August 27, 2013 Accepted 19 October 2013 Available online 20 October 2013 A mild and efficient procedure has been proposed for oxidation of benzylic alcohols to the corresponding carbonyl compounds using polymer-supported dichloroiodate (PSDI). The oxidations were carried out in acetonitrile solution, affording the corresponding aldehydes or ketones in high substrate conversion and short reaction time under mild aprotic conditions. Excellent selectivity was observed between primary benzyl alcohols and secondary ones as well as non-benzylic alcohols in the oxidation reactions. The catalyst can be easily prepared and regenerated. © 2013 Growing Science Ltd. All rights reserved.

Release of iodine from organic matter in natural water by K2S2O8oxidation for129I determination

Accelerator mass spectrometry is the only method for measuring 129I in low level environmental samples. In this method, it is essential to convert organic associated iodine into inorganic form for the determination of total 129I or organic 129I because AgI is usually adopted as a target for AMS measurement of 129I. The chemical oxidative method to release iodine from organic matter in natural water was investigated using anion exchange chromatography and CHCl3 extraction methods. K2S2O8 was confirmed to be an ideal oxidative reagent for decomposing organic matters and converting organic iodine to inorganic form. More than 95% of iodine in natural water can be separated by solvent extraction after oxidation under optimal conditions, and the isotopic exchange of iodine in inorganic and organic forms was well completed during the oxidation, being able to result in an identical 129I/127I ratio as in the original water. Our works indicate that the reported chemical oxidation method is a suitable approach for releasing organic associated iodine in natural water to allow separation of iodine and preparation of the AgI target for AMS measurement.

On line vapor generation of osmium based on solution cathode glow discharge for the determination by ICP-OES

A novel plasma induced vapor generation method is proposed to determine osmium in solutions. Without any chemical oxidizing agents, osmium ion can be readily converted to volatile osmium tetraoxide vapor in the solution cathode glow discharge (SCGD) system. The generated osmium vapor is then transported to inductively coupled plasma for determination by optical emission spectrometry. The influences of background electrolyte, carrier gas flow rate, sample flow rate, ICP power and discharge current were investigated. The analytical performances of this proposed technique were evaluated under optimized conditions. The detection limit of Os was calculated to be 0.51ngmL−1. The reproducibility, expressed as the relative standard deviation (n=11) of a 2.0μgmL−1 standard solution, was 1.9%. This SCGD induced vapor generation is sensitive and simple, oxidation reagents free, providing an alternative analytical method for measuring Os in geological or environmental water samples.

Modified McFadyen–Stevens reaction for a versatile synthesis of aliphatic/aromatic aldehydes: design, optimization, and mechanistic investigations

The traditional McFadyen–Stevens reaction requires harsh alkaline reaction conditions, thus precluding application to the synthesis of aliphatic aldehydes. Our modified McFadyen–Stevens reaction enables the transformation from the N,N-acylsulfonyl hydrazine to the corresponding aldehyde upon treatment with an imidazole–TMS imidazole combination without relying on oxidative or reductive reagents. The reduced basicity and in situ protection of the resulting aldehyde widens the substrate scope to include aliphatic aldehydes, even ones bearing an α-hydrogen atom. Close examination of the side reactions for particular substrates in combination with theoretical considerations via DFT calculations led to a mechanistic understanding of the McFadyen–Stevens reaction involving an acyl diazene and a hydroxy carbene as reasonable intermediates.

Recent Progress in Photocatalysis Mediated by Colloidal II‐VI Nanocrystals

The use of photoexcited electrons and holes in semiconductor nanocrystals as reduction and oxidation reagents is an intriguing way of harvesting photon energy to drive chemical reactions. This review focuses on recent research efforts to understand and control the photocatalytic processes mediated by colloidal II-VI nanocrystalline materials, such as cadmium and zinc chalcogenides. First, we highlight how nanocrystal properties govern the rates and efficiencies of charge-transfer processes relevant to photocatalysis. We then describe the use of nanocrystal catalyst heterostructures for fuel-forming reactions, most commonly H2 generation. Finally, we review the use of nanocrystal photocatalysis as a synthetic tool for metal–semiconductor nano-heterostructures.

γ-Ray induced catalytic properties of the silica nanoparticles dispersed in the aerated aqueous solution

Silica nanoparticles (NPs) dispersed in an aerated aqueous solution containing Ag+ were irradiated to a dose of 10 kGy using 60Co γ-rays. The typical surface plasmon band of Ag NPs was observed around 400 nm, indicating that even in the presence of dissolved oxygen the reduction of Ag+ occurred by silica NPs. Transmission electron microscopy images indicated that Ag NPs formed on the surface of the silica NPs. The subtraction spectra showed broad absorption around 500 nm with the absorbance depending on the dose. The electrons generated by charge separation from silica NPs with a size of about 12 nm reduce Ag+ to Ag0 and form (Ag0) n species on the silica NPs, and the type of (Ag0) n species formed depended on the silica NP, and Ag+ contents, and the dose. In the co-presence of organic molecules on the silica NP such as rhodamine, the absorbance of the surface plasmon band of both Ag NPs and rhodamine decreased, indicating the electrons to participate in the reductive decomposition of rhodamine molecules adsorbed on the silica NP. Furthermore, in the case when the silica NPs contained fluorescein molecules, the fluorescein molecules were also decomposed, indicating that the fluorescein molecules adsorbed on the inner surface of the silica NPs. The addition of I2 as an oxidative reagent prevented the decomposition of the fluorescein molecules, indicating that electrons are the main species emitted from irradiated silica NPs.

ChemInform Abstract: Synthesis of Ketone from Alkyl Halide Using α‐Chloro Nitrone as Oxidizing Reagent: A New Approach.

AbstractCompound (IV), formed as by‐product during the oxidation of isopropyl bromide (Ia) with N‐phenyl α‐chloronitrone in low yield, can itself undergo cycloaddition reaction.

Radiolabeling of aromatic compounds using K[*Cl]Cl and OXONE®

We report a novel labeling method for the rapid radiochlorination of aromatic compounds using no-carrier-added short-half-life radioactive chloride ions ([38,39Cl]Cl− and [34mCl]Cl−) and OXONE® (Sigma-Aldrich, Japan) as an oxidation reagent. The reaction of radioactive chloride ions with anisole in the presence of OXONE gave a mixture of p-[*Cl]chloroanisole and o-[*Cl]-chloroanisole, with a radiochemical conversion yield of more than 85% (not decay corrected) and selectivity of 7:3, within 10 min. Regioselective radioactive chlorination was achieved by chlorodestannylation of tributylstannyl compounds to afford the corresponding radiochlorinated compounds (p-chloroanisole and m-chloroanisole) in satisfactory radiochemical yields (80–95% and 46–65%, respectively). Copyright © 2012 John Wiley & Sons, Ltd.

Multiplexed Enrichment and Detection of Malarial Biomarkers Using a Stimuli-Responsive Iron Oxide and Gold Nanoparticle Reagent System

There is a need for simple yet robust biomarker and antigen purification and enrichment strategies that are compatible with current rapid diagnostic modalities. Here, a stimuli-responsive nanoparticle system is presented for multiplexed magneto-enrichment and non-instrumented lateral flow strip detection of model antigens from spiked pooled plasma. The integrated reagent system allows purification and enrichment of the gold-labeled biomarker half-sandwich that can be applied directly to lateral flow test strips. A linear diblock copolymer with a thermally responsive poly(N-isopropylacrylamide) (pNIPAm) segment and a gold-binding block composed of NIPAm-co-N,N-dimethylaminoethylacrylamide was prepared by reversible addition-fragmentation chain transfer polymerization. The diblock copolymer was used to functionalize gold nanoparticles (AuNPs), with subsequent bioconjugation to yield thermally responsive pNIPAm-AuNPs that were co-decorated with streptavidin. These AuNPs efficiently complexed biotinylated capture antibody reagents that were bound to picomolar quantities of pan-aldolase and Plasmodium falciparum histidine-rich protein 2 (PfHRP2) in spiked pooled plasma samples. The gold-labeled biomarker half-sandwich was then purified and enriched using 10 nm thermally responsive magnetic nanoparticles that were similarly decorated with pNIPAm. When a thermal stimulus was applied in conjunction with a magnetic field, coaggregation of the AuNP half-sandwiches with the pNIPAm-coated iron oxide nanoparticles created large aggregates that were efficiently magnetophoresed and separated from bulk serum. The purified biomarkers from a spiked pooled plasma sample could be concentrated 50-fold into a small volume and applied directly to a commercial multiplexed lateral flow strip to dramatically improve the signal-to-noise ratio and test sensitivity.

Manganese Dioxide Supported on Aluminum Silicate: A New Reagent for Oxidation of Alcohols Under Heterogeneous Conditions

Manganese dioxide supported on aluminum silicate, under heterogeneous conditions at reflux, selectively oxidized aromatic primary and secondary alcohols into the corresponding aldehydes and ketones, respectively, in yields of 87–96%. The present method failed to oxidize aliphatic alcohols.

Theoretical study on the oxidation of zigzag silicon carbide nanotubes (SiCNTs) by singlet O2

Singlet O 2 produced upon photoexcitation is a very important oxidative reagent. The study on its reaction with nanotube might be useful not only to evaluate the stability of the nanotube upon air exposure and sunlight, but also to modify the properties of the nanotube. Considering the unique properties and wide applications of silicon carbide nanotube (SiCNT), in this paper, we performed extensive density functional theory (DFT) calculations to study the oxidation of a series of zigzag ( n ,0) SiCNTs ( n =6 to 12) by singlet O 2 . It is found that the reaction process contains two steps, namely, (i) [2+2] cycloaddition of a singlet O 2 to the Si–C bond, followed by (ii) the dissociation of the O–O bond, leading to the formation of an epoxide configuration with a highly exothermicity (>4.00 eV). Compared with pure SiCNT, the cycloaddition of singlet O 2 on tube leads to the decrease of the band gap, while the formation of the stable epoxy structure render band gap increase. Our results indicate that the SiCNT is more prone to be degraded after exposure to air and sunlight.

Graphite oxide: an efficient reagent for oxidation of alcohols under sonication

Graphite oxide (GO) was used as an effective oxidizing agent for the synthesis of aldehydes and ketones from various alcohols under ultrasonic irradiation. Under optimized conditions, quantitative yields of the products were obtained. Compared to other reagents used for the same chemical transformation, GO displays several advantages, including low cost, ease of synthesis, and high stability to ambient conditions.

ChemInform Abstract: Facile Preparation and Reactivity of Bifunctional Ionic Liquid Supported Hypervalent Iodine Reagent: A Convenient Recyclable Reagent for Catalytic Oxidation.

AbstractTEMPO derivatives (I) and (II) are synthesized and successfully tested as recycable catalysts for the peracid oxidation of a broad spectrum of primary and secondary alcohols to the corresponding carbonyl compounds.

Synthesis of functionalized furo[3,2-c]coumarins via a one-pot oxidative pseudo three-component reaction in poly(ethylene glycol)

An efficient and straightforward synthesis of functionalized furo[3,2-c]coumarins via a one-pot oxidative pseudo three-component condensation of aldehydes and 4-hydroxycoumarin (2equiv) in poly(ethylene glycol) (PEG) as solvent is described. A mixture of I2 and K2S2O8 in the presence of Na2CO3 was used as an oxidative reagent. The structure of the furo[3,2-c]coumarins was established by X-ray single crystal structure analysis.

Stable isotope analysis of Nd by double spike thermal ionization mass spectrometry

We report a high-precision stable isotopic analysis of Nd using double spike thermal ionization mass spectrometry (DS-TIMS). The analysis protocol of the DS-TIMS technique is refined to include internal normalization and iterative calculation to achieve high precision and minimize systematic bias during data analysis. Nd stable isotope ratios are reported in a standard epsilon notation relative to JNdi-1, a common isotopic reference material for the radiogenic 143Nd/144Nd ratio. With this technique, the ɛ146Nd, parts par 104 difference of the 146Nd/144Nd ratio relative to that of JNdi-1, can be measured with a typical precision of ±0.3 epsilon units. The precision and accuracy of this refined DS-TIMS technique are demonstrated by 2 analyses. First, Nd isotope fractionation during the cation exchange column chromatography is investigated. A known amount of JNdi-1 is eluted from a column filled with a cation exchange resin by using HIBA as a solute and is sequentially collected into 7 fractions. The Nd stable isotopic composition of the 7 fractions systematically changed from ɛ146Nd=4.60 during the early stage of elution to ɛ146Nd=−9.44 during the late stage of elution in a mass-dependent manner. Using the elution data, the Nd isotope fractionation factor between the cation exchange resin and the solute (HIBA) at room temperature is determined as α146, resin–HIBA=0.999964±0.000003. Second, Nd stable isotopic variation among commercial high-purity Nd oxide reagents is investigated. The ɛ146Nd of 10 commercial Nd oxide reagents and La Jolla Nd vary significantly from −2.36 to 0.23. The stable isotopic composition of La Jolla Nd (ɛ146Nd=−1.97±0.23) is clearly different from that of JNdi-1. The isotopic variation of the reagents agrees with the mass-dependent isotopic fractionation trend. The Nd stable isotopic variation among the reagents may be caused by isotope fractionation during the reagent production process and/or may be inherited from the source materials of the reagents.

Purification and partial characterization of glyceraldehyde-3-phosphate dehydrogenase from the ciliate <italic>Tetrahymena thermophila</italic>

In the present study, we purified the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) which is involved in cellular energy production and has important housekeeping functions, from the ciliate Tetrahymena thermophila using a three-step procedure. The enzyme was purified ~68 folds by ammonium sulfate precipitation, followed by two steps of column chromatography (DEAE-cellulose and Mono-S). The purified enzyme is a homotetramer with a molecular weight of ~120 kDa. Isoelectric focusing analysis showed the presence of only one basic GAPDH isoform with an isoelectric point of 8.8. Western blot analysis showed a single 32-kDa band corresponding to the enzyme subunit using a monospecific polyclonal antibody against the T. thermophila GAPDH. The maximum of enzyme activity occurred at pH 8.0 and at 30-35°C. The apparent K(m) values for both NAD(+) and D-glyceraldehyde-3-phosphate were 0.102 ± 0.012 and 0.360 ± 0.018 mM, respectively. The maximal velocity (V(max)) was 39.40 ± 2.95 U/mg. The T. thermophila GAPDH is inhibited by oxidative and nitrosative stress reagents.