Showing papers on "Reagent published in 2005"
793 citations
TL;DR: A great difference was found between the measured total organic carbon (TOC) and the amount of carbon in all analyzed species in the reaction medium, indicating that the unidentified compounds must correspond to oxidation intermediates between phenol and the organic acids.
Abstract: Phenol oxidation by Fenton's reagent (H2O2 + Fe2+) in aqueous solution has been studied in depth for the purpose of learning more about the reactions involved and the extent of the oxidation proces...
554 citations
TL;DR: Merc Mercuryfluor-1 (MF1) is a water-soluble, fluorescein-based reagent that features excellent selectivity for Hg2+ over competing analytes and the largest turn-on fluorescence response to date for reporting this heavy metal ion in aqueous solution.
Abstract: Societal concerns over toxic mercury accumulation in humans from fish and other dietary and environmental sources provide motivation to develop new tools and tactics for mercury detection in a wide range of laboratory and field settings. Here we report the synthesis, properties, and application of a selective and sensitive small-molecule chemosensor for fluorescence screening of mercury levels in fish. Mercuryfluor-1 (MF1) is a water-soluble, fluorescein-based reagent that features excellent selectivity for Hg2+ over competing analytes and the largest turn-on fluorescence response to date (>170-fold increase) for reporting this heavy metal ion in aqueous solution. Combining this chemoselective Hg2+ probe with a microwave digestion protocol provides a facile method for assaying mercury levels in fish samples with mercury concentrations spanning 0.1 to 8 ppm, a range well matched with the United States Environmental Protection Agency (U.S. EPA) standard for the maximum safe level of mercury in edible fish (...
490 citations
TL;DR: A novel C-C bond formation method was developed via the cross-dehydrogenative-coupling reaction catalyzed by using copper bromide in the presence of an oxidation reagent, tert-BuOOH.
Abstract: A novel C−C bond formation method was developed via the cross-dehydrogenative-coupling (CDC) reaction catalyzed by using copper bromide in the presence of an oxidizing reagent, tert-BuOOH. The CDC reaction provides a simple and efficient catalytic method to construct β-nitroamine via the reaction between sp3 C−H and sp3 C−H bonds.
472 citations
TL;DR: It is demonstrated that Fenton's reagent can effectively degrade leachate organics andSludge settling characteristics were much improved with the addition of the proper polymer and temperature gave a positive effect on organic removal.
389 citations
TL;DR: In this paper, the influence of sacrificial reagents on the photocatalytic efficiency in water splitting reactions under ultraviolet (UV) irradiation was examined, where various reagents such as methanol, Na2S, and ethylene diamine tetraacetic acid (EDTA), as well as I- and IO3- ions were used to obtain an effective water splitting to H and O atoms.
Abstract: Hydrogen production by water splitting over a Pt−TiO2 catalyst has been studied. The main goal of the studies was to examine the influence of sacrificial reagents on the photocatalytic efficiency in water splitting reactions under ultraviolet (UV) irradiation. Various sacrificial reagents, such as methanol, Na2S, and ethylene diamine tetraacetic acid (EDTA), as well as I- and IO3- ions, were used to obtain an effective water splitting to H and O atoms. It was revealed that, in the case of using methanol as the sacrificial reagent, hydrogen evolution is also a result of methanol conversion. Photocatalytic water splitting was obtained when EDTA and Na2S were used as the sacrificial reagents.
347 citations
TL;DR: Zeta potentials can be used to delineate interfacial phenomena in these various systems where the collector is physically adsorbed, and raising the pH sufficiently above the PZC can repel chemisorbing collectors from the mineral surface.
308 citations
TL;DR: In this paper, a safe, convenient preparation of the reagent sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBArF24) has been devised by utilizing a magnesium−bromine exchange reaction in the absence of metallic magnesium.
281 citations
TL;DR: The use of modified Fenton's reagent, or catalyzed H2 O2 propagations (CHP), has become increasingly popular for the in situ and ex- situ treatment of surface soils and in situ remediation of the subsurface.
Abstract: The use of modified Fenton’s reagent, or catalyzed H2 O2 propagations (CHP), has become increasingly popular for the in situ and ex situ treatment of surface soils and the in situ remediation of the subsurface. The process is based on the catalyzed decomposition of hydrogen peroxide by soluble iron, iron chelates, or iron minerals to generate the strong oxidant hydroxyl radical as well as other reactive oxygen species. Some of these species function as reductants and nucleophiles and may be responsible for the enhanced treatment of sorbed and nonaqueous phase liquid (NAPL) contaminants that is sometimes observed in the field. This paper serves as a review of the process chemistry of CHP; the goal is to provide researchers and practitioners with fundamental concepts that will aid in applying the CHP process to soil and groundwater contamination. Although the importance of well placement and the method of reagent injection must be considered in CHP remediation, understanding and promoting the most effective...
260 citations
TL;DR: Calcium phosphate nanoparticles were found to be dissolved even in low acidic buffer (pH 5.0) releasing the pDNA, which suggested that DNA release from these particles in the endosomal compartment was possible.
245 citations
TL;DR: In this article, the design and operation of liquid-liquid and gas-liquid immiscible systems depend mainly on the method of dispersion/phase contacting, whilst gas liquid and gas liquid systems depend not only on the phase contacting, but also on the solid integration principles employed.
TL;DR: The effects of the molar ratios of tartrate anions and NaOH to Cu(2+) cations, reagent concentration, and reaction temperature on the products were investigated, showing that the morphology of CPMs was determined by the molars ratio of Tartrate to Cu (2+)cations and the size was greatly affected by reagent concentrations.
Abstract: A simple aqueous solution route was introduced for the fabrication of CuO pricky microspheres (CPMs) using CuCl2·2H2O, Na2(C4H4O6)·3H2O and NaOH as starting materials. The CPMs were composed of compressed nanothorns exhibiting tapering feature with tip size of less than 10 nm, and the size of CPMs could be tuned from 100−200 nm to 4−6 μm. The effects of the molar ratios of tartrate anions and NaOH to Cu2+ cations, reagent concentration, and reaction temperature on the products were investigated, showing that the morphology of CPMs was determined by the molar ratio of tartrate to Cu2+ cations and the size was greatly affected by reagent concentration and the molar ratio of NaOH to Cu2+ cations in the precursor solution. The fabrication of CPMs went through rapid nucleation of Cu(OH)2, aggregation and in situ dehydration of Cu(OH)2, oriented-aggregation-based growth, and normal crystal growth of CuO nanothorns. The nucleation and crystal growth were successfully separated by controlled releasing of Cu2+ and...
TL;DR: 3,5-Disubstituted isoxazoles are obtained in good yields by a convenient one-pot, three-step procedure utilizing a regioselective copper(I)-catalyzed cycloaddition reaction between in situ generated nitrile oxides and terminal acetylenes.
Abstract: [reaction: see text] 3,5-Disubstituted isoxazoles are obtained in good yields by a convenient one-pot, three-step procedure utilizing a regioselective copper(I)-catalyzed cycloaddition reaction between in situ generated nitrile oxides and terminal acetylenes. Most functional groups do not interfere with the reaction, which can be performed in aqueous solvents without protection from oxygen. Since all reagents are used in stoichiometric amounts, formation of byproducts is minimized.
TL;DR: No pH adjustment was required, as well as no iron addition due to the presence of iron oxides in the solid matrices, suggesting the potential application of Fenton-like treatment for the remediation of PAH-contaminated environmental solids.
TL;DR: The line color intensity of an aflatoxin B(1)-positive dipstick is visually distinguishable from that of anAflatoxin bovine serum albumin conjugate-negative sample, and the visual detection limit for aflat toxin B( 1) is 5 microg/kg.
Abstract: The aim of this work was to develop an immunoassay-based lateral flow dipstick for the rapid detection of aflatoxin B1 in pig feed. The test consisted of three main components: conjugate pad, membrane, and absorbent pad. The membrane was coated with two capture reagents, that is, aflatoxin B1−bovine serum albumin conjugate and rabbit anti-mouse antibodies. The detector reagent consisted of colloidal gold particles coated with affinity-purified monoclonal anti-aflatoxin B1 antibodies, which saturated the conjugate pad. A comparison of several extraction methods for the pig feed matrix is presented. A mixture of methanol/water (80:20, v/v) gave the best recoveries. After sample extraction and dilution, the dipstick was put in the sample solution at the conjugate pad side and developed for 10 min. Analyte present in the sample competed with the aflatoxin B1 immobilized on the membrane for binding to the limited amount of antibodies in the detector reagent. Thus, the line color intensity of an aflatoxin B1-p...
TL;DR: The experimental results clearly showed that these fluorescent probes are good protein indicators for easy and highly sensitive detection.
Abstract: Novel fluorescent molecular probes possessing both a hydroxystyryl and a cyanopyranyl moieties were designed and synthesized to detect the proteins via noncovalent bonding. These fluorescent probes indicated very weak fluorescence emission in the absence of protein. On the other hand, the fluorescence spectra of these probes showed a large Stokes shift and dramatic increase of fluorescence intensity, and red emission was observed after addition of BSA. These fluorescence spectral changes upon binding proteins were caused by the ICT process. Fluorescence intensities of the probes were plotted as a function of protein concentrations. A good linear relationship was observed up to 1000 μg/mL of protein, and the detection limit was found to be 100 ng/mL at the given assay conditions. Similar results were observed for the measurements of not only BSA but also other proteins (BGG, etc.). The responses of these probes to various nonprotein substances (inorganic salts, chelating agents, etc.) were observed, the fl...
TL;DR: In this article, the results of studies on the properties of subcritical and supercritical water are generalised and the possibility of using such water as a solvent, a reagent or a catalyst in chemical reactions is considered.
Abstract: The results of studies on the properties of subcritical and supercritical water are generalised. The possibility of using such water as a solvent, a reagent or a catalyst in chemical reactions is considered. Primary attention is paid to specific features of experimental research under hydrothermal conditions. Prospects for use of subcritical and supercritical water in heterogeneous catalysis for the preparation of nanocrystalline materials with predictable properties and for solving environmental problems are discussed.
TL;DR: In this paper, a multivariate experimental design methodology was applied having in mind the optimization of the azo dye Orange II degradation using the Fenton's reagent (mixture of H 2 O 2 and Fe 2+ ).
TL;DR: Catalytic use of o-iodoxybenzoic acid (IBX) in the presence of Oxone as a co-oxidant is demonstrated for the oxidation of primary and secondary alcohols in user- and eco-friendly solvent mixtures.
TL;DR: DFT calculations of C-H hydroxylation by a synthetic nonheme oxoiron(IV) oxidant supported by a neutral pentadentate N5 ligand show that this reagent is intrinsically more reactive than compound I of P450.
Abstract: DFT calculations of C−H hydroxylation by a synthetic nonheme oxoiron(IV) oxidant supported by a neutral pentadentate N5 ligand show that this reagent is intrinsically more reactive than compound I of P450. This nonheme iron oxidant is predicted to exhibit stereoselective reactions, strong solvent effect, and involve multistate reactivity with spin-state crossing.
TL;DR: 1,2-Dipyridiniumditribromide-ethane (DPTBE) has been synthesized and explored as a new efficient brominating agent that has high active bromine content per molecule and shows a remarkable reactivity compared to other tribromide reagents toward various substrates.
Abstract: 1,2-Dipyridiniumditribromide-ethane (DPTBE) has been synthesized and explored as a new efficient brominating agent. The crystalline ditribromide reagent is stable for months and acts as a safe source of bromine requiring just 0.5 equiv for complete bromination. It has high active bromine content per molecule and shows a remarkable reactivity compared to other tribromide reagents toward various substrates by just grinding the reagent and substrates in a porcelain mortar at room temperature. No organic solvent has been used during any stage of the reaction for substrates giving product as solid. Product can easily be isolated by just washing the highly water soluble 1,2-dipyridiniumdibromide-ethane (DPDBE) from the brominated product. The spent reagent can be recovered, regenerated, and reused without any significant loss.
TL;DR: In this paper, an experimental study was carried out to obtain the reactivity of different organic sulfur compounds and to examine the effect of various parameters, such as temperature, solvent and the amount of oxidant reagent in ODS reaction.
TL;DR: Treatment of beta-keto phosphonates with N-fluorobenzenesulfonimide as electrophilic fluorinating reagent and diethyl azodicarboxylate as Electrophilic amination reagent under mild reaction conditions afforded the corresponding alpha-substituted beta- keto phosphate in moderate to excellent yields with excellent enantiomeric excesses.
TL;DR: In this article, the authors investigated the synergistic effects of Cyanex 272 mixed with D2EHPA and Cyanex 302 mixed with EHPA for the separation of cobalt and nickel from a dilute sulfate media.
TL;DR: Polyglycerol supported reagents and scavengers as well as scavengers PG-carbonate, PG-carbazate, and PG-amine, which all have been synthesized in high overall conversions and yields using simple purification techniques, are presented.
Abstract: In this paper we present soluble dendritic polyglycerol (PG) supported reagents PG-DEAD, PG-PPh3, and PG-DCC as well as scavengers PG-carbonate, PG-carbazate, and PG-amine, which all have been synthesized in high overall conversions and yields using simple purification techniques. The supported reagents have been used simultaneously in Mitsunobu and acylation reactions. All polymeric reagents and scavengers can be removed by simple precipitation/filtration protocols to give chromatography-free products of high purity. In the course of the syntheses of the polymeric reagents three intermediates turned out to be precious polyglycerol derivatives: a mixed carbonate as an electrophilic derivative, polyglyceryl carbazate as a scavenger for carbonyl compounds, as well as polyglycerylamines as amino analogues of polyglycerol.
TL;DR: In this paper, the coupling reaction of silyl hydrides with alkoxysilanes to produce siloxanes and hydrocarbons catalyzed by tris(pentafluorophenyl)borane was studied by gas chromatography and UV spectroscopy using model reagent systems.
TL;DR: In this paper, the effects from the preparation of glyoxal solution, e.g., concentration and pH, and the reaction condition, such as time and temperature, were studied.
TL;DR: Both aliphatic and aromatic nitriles are conveniently and selectively converted in a single step, via an indirect acid-catalyzed hydration, into the corresponding amides in 1-8 h using a TFA-H2SO4 mixture as a reagent system.
Abstract: Both aliphatic and aromatic nitriles are conveniently and selectively converted in a single step, via an indirect acid-catalyzed hydration, into the corresponding amides in 1-8 h using a TFA-H 2 SO 4 mixture as a reagent system. Although the same reagent did not work for the sterically hindered nitriles such as mesitonitrile, the transformation could be accomplished by changing TFA to AcOH at higher temperatures (>90 °C).
TL;DR: The high efficiency and versatility of this new generation of TBCRs confirm, for the first time, the usefulness of the concept of "superactive esters" in rational design of the structure of coupling reagents.
Abstract: A new generation of triazine-based coupling reagents (TBCRs), designed according to the concept of “superactive esters”, was obtained by treatment of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium (DMTMM) chloride with lithium or silver tetrafluoroborate. The structure of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium tetrafluoroborate was confirmed by X-ray diffraction. Activation of carboxylic acids by using this reagent proceeds via triazine “superactive ester”. The coupling reagent was successfully used for the synthesis of Z-, Boc-, and Fmoc-protected dipeptides derived from natural and unnatural sterically hindered amino acids and for fragment condensation, in 80−100% yield and with high enantiomeric purity. The manual SPPS of the ACP(65−74) peptide fragment (H-Val-Gln-Ala-Ala-Ile-Asp-Tyr-Ile-Asn-Gly-OH) proceeded significantly faster than with TBTU or HATU, as well as the automated SPPS of the same fragment gave a purer product than by using TBTU or PyBOP. The reagent was also...
TL;DR: Analyses using this new scheme of an ICAT‐labeled trypsin‐digested six protein mixture as well as a tryptic digest of a total yeast lysate indicated that about two times more proteins were identified in a single analysis, and that there was no loss in accuracy of quantification.
Abstract: Quantitative protein profiling using the isotope-coded affinity tag (ICAT) method and tandem mass spectrometry (MS) enables the pair-wise comparison of protein expression levels in biological samples. A new version of the ICAT reagent with an acid-cleavable bond, which allows removal of the biotin moiety prior to MS and which utilizes (13)C substitution for (12)C in the heavy-ICAT reagent rather than (2)H (for (1)H) as in the original reagent, was investigated. We developed and validated an MS data acquisition strategy using this new reagent that results in an increased number of protein identifications per experiment, without losing the accuracy of protein quantification. This was achieved by following a single survey (precursor) ion scan and serial collision induced dissociations (CIDs) of four different precursor ions observed in the prior survey scan. This strategy is common to many high-performance liquid chromatography-electrospray ionization (HPLC-ESI)-MS shotgun proteomic strategies, but heretofore not to ICAT experiments. This advance is possible because the new ICAT reagent uses (13)C as the "heavy" element rather than (2)H, thus, eliminating the slight delay in retention time of ICAT-labeled "light" peptides on a C18-based HPLC separation that occurs with (2)H and (1)H. Analyses using this new scheme of an ICAT-labeled trypsin-digested six protein mixture as well as a tryptic digest of a total yeast lysate, indicated that about two times more proteins were identified in a single analysis, and that there was no loss in accuracy of quantification.