Oxidation of Carbamazepine by Lipopathic Mn(VII), Cetyltrimethylammonium Permanganate: A Mechanistic Study

In this contribution, we report the oxidation of an established anticonvulsant and antiepileptic drug, carbamazepine, by a lipopathic oxidant, cetyltrimethylammonium permanganate (CTAP), in a nonpolar medium. 1H‐Dibenzo[b,f]azepine‐4,5‐dione is found to be the major product of the oxidation reaction. The kinetics of the reaction is studied in organic media spectrophotometrically by monitoring the disappearance of Mn(VII) at 530 nm. The reaction is found to be fractional order with respect to carbamazepine and first order with respect to CTAP. Based on the experimental findings, a suitable ionic mechanism is proposed where carbamazepine reacts with CTAP in a slow rate‐determining step to form a hypomanganate ester intermediate through a nonpolar cyclic transition state. Subsequently, the intermediate decomposes and hydrolyzes in fast steps to the dicarbonyl product. The proposed reaction mechanism is also supported by the effect of solvent and temperature on the rate of the reaction. The addition of ionic surfactants increases the rate of reaction, and the catalyzing effect is explained through the possible formation of mixed reverse micellar aggregates where carbamazepine is partitioned more to the interfacial region in the vicinity of the permanganate anion.     

Sensitivity enhancement of liquid chromatographic-direct chemiluminescence detection by on-line post-column solvent mediated pre-oxidative chemiluminescence

The compatibility of liquid chromatography solvents with oxidizing reagents frequently employed in direct chemiluminescence reactions is examined in this study. Various oxidizing reagents were examined for their response in hydro-organic and micellar mobile phases in both isocratic and gradient elution modes. Mild oxidants like hydrogen peroxide, periodate, cerium and hypochlorite were found to be completely compatible with common reversed phase HPLC solvents posing as no threat to the detection procedure. On the other hand, stronger oxidants like acidic permanganate were found to oxidize organic solvents towards the production of an intense light signal. Although several analytical applications can emerge from this finding, the conjunction of this system with reversed phase HPLC is impractical owing to a significant baseline increase which deteriorates the sensitivity of the analysis. A convenient solution to this problem is proposed based on the regulated on-line post-column pre-oxidation of the organic solvent (SPOC) with mild oxidants that have no influence on the final signal. The analytical utility of this new approach in the determination of organic compounds after chromatographic separation is demonstrated.     

Gasometric microdetermination of hydrazine compounds by oxidation with some inorganic oxidants in basic media

Summary Oxidation of hydrazine compounds by many inorganic oxidants, of different nature, in basic media is critically studied. Basic solutions of hexacyanoferrate(III), permanganate, iodine, copper(II), silver(I) and potassium mercuric iodide are used, the latter being the most suitable one. The optimum conditions under which nitrogen is quantitatively liberated are defined. A suitable procedure for the gasometric microdetermination of the hydrazine function in different organic and inorganic samples is described.

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Gasometrische Mikrobestimmung von Hydrazinverbindungen durch Oxydation mit anorganischen Oxydationsmitteln in alkalischer Lösung

Zusammenfassung Folgende Oxydationsmittel wurden verwendet: Hexacyanoferrat(III), Permanganat, Jod, Kupfer(II), Silber(I) sowie Kaliumquecksilberjodid. Letzteres erwies sich als am besten geeignet zur Bestimmung verschiedenartiger anorganischer und organischer Hydrazinverbindungen. Die optimalen Reaktionsbedingungen wurden untersucht und eine entsprechende Arbeitsvorschrift ausgearbeitet.

     

Effect of oxidant type on the chemiluminescence intensity from the reaction of tris(2,2′-bipyridyl)ruthenium(III) with various organic acids

An investigation into the chemiluminescence of fourteen organic acids and tris(2,2′-bipyridyl)ruthenium(II) was undertaken. Particular emphasis was placed upon the method of production of the reagent, tris(2,2′-bipyridyl)ruthenium(III), with cerium(IV) sulfate, potassium permanganate, lead dioxide and electrochemical generation. Analytically useful chemiluminescence was observed when Ce(IV) or potassium permanganate were employed as oxidants. The kinetics of analyte oxidation was related to the intensity of the chemiluminescence emission, which increased by three orders of magnitude for tartaric acid after 40 h of oxidation.     

Selective role of oxidants in the presence of cation-exchange resins in Na(+)-form for the detection and differentiation of acidic, basic and neutral amino-acids

A test for detection and differentiation of acidic, basic and neutral amino-acids is based on use of a sulphonic acid cation-exchange resin in Na(+)-form, in the presence of various oxidants (permanganate, dichromate, chromate, iodate, peroxide) and final detection with Nessler's reagent.     

Some comments on the thermal stability of substituted ammonium,phosphonium, and arsonium permanganates and their use in alkane oxidation

Tetraethyl- and tetrabutylammonium permanganate are less prone to explosive decomposition when heated than are benzyl(triethyl)ammonium and methyl-(triphenyl) phosphonium permanganate and are about equally effective as oxidants for the conversion of alkanes into alcohol and ketones.     

Utilization of ion exchangers in analytical chemistry XXVI : Application of the ion-exchange method to solutions containing oxidants

The free acid form of a cation-exchange resin of the sulfonated hydrocarbon type (Dowex 50) can be used for a quantitative liberation of the corresponding acids from salt solutions containing oxidants that are reduced by phenolic resins. Positive results have been obtained with solutions containing bromate, iodate, periodate, molybdate, and chromate. With permanganate a partial reduction occurs which prevents the application of the ion-exchange method for quantitative separation of solutions containing permanganate.     

Classical oxidant induced chemiluminescence of fluorescent carbon dots

We report new chemiluminescent properties of fluorescent carbon dots in the presence of classical oxidants, such as acidic potassium permanganate and cerium(IV). The radiative recombination of oxidant-injected holes and electrons in the carbon dots accounts for the CL emission, which sheds new light on characteristics of the carbon dots.     

Iodine(III) mediators in electrochemical batch and flow reactions

The anodic oxidation of aryl iodides is a powerful method for synthesis of hypervalent iodine compounds, which have matured to frequently used reagents in organic synthesis. The electrochemical route eliminates the use of expensive or hazardous oxidants for their synthesis. Hypervalent iodine reagents generated at the anode are successfully used as either in-cell or ex-cell mediators for many valuable chemical transformations including fluorinations and oxidative cyclisations. The recent advances in the area of flow electrochemistry are providing additional benefits and allow new synthetic applications. Mechanistic insights and novel technologies enable the development of new concepts for sustainable chemistry.     

Kinetics of polymerization of acrylonitrile initiated by acidic permanganate/thioacetamide redox system

The kinetics of vinyl polymerization of acrylonitrile (AN) initiated by an acidic permanganate/thioacetamide (TAm) redox system have been investigated in aqueous media at 30 ± 0.2°C in nitrogen, and the rate of polymerization measured. The effect of additives like organic solvents, neutral electrolytes, and complexing agents on the rate have been assessed. Based on the experimental results, a suitable reaction scheme involving initiation by organic free radicals generated by the interaction of Mn(IV) with protonated thioacetamide and termination by Mn(III) has been suggested. Various rate and energy parameters have been evaluated.     

The carbon nanotubes-based materials and their applications for organic pollutant removal:A critical review

The carbon nanotubes(CNTs) as the emerging materials for organic pollutant removal have gradually become a burgeoning research field.Herein,a mini-review of CNTs-based materials curre ntly studies for organic pollutant elimination is presented.This review summarizes the preparation methods of CNTsbased materials.CNTs-based materials can be used as adsorbents to remove organic pollutants in wastewater.The adsorption mechanisms mainly include surface diffusio n,pore diffusion and adsorption reaction.Most importantly,an in-depth overview of CNTs-based materials currently available in advanced oxidation processes(AOPs) applications for wastewater treatment is proposed.CNTs-based materials can catalyze different oxidants(e.g.,hydrogen peroxide(H_2 O_2),persulfates(PMS/PDS),ozone(O_3) and ferrate/permanganate(Fe(Ⅵ)/Mn(Ⅶ)) to generate more reactive oxygen species(ROS) for organic pollutant elimination.Moreover,the possible reaction mechanisms of removing organic pollutants by CNTs-based materials are summarized systematically and discussed in detail.Finally,application potential and future research directions of CNTs-based materials in the environmental remediation field are proposed.     

Electrochemically promoted N-heterocyclic carbene polymer-catalyzed cycloaddition of aldehyde with isocyanide acetate

Science China Chemistry - N-heterocyclic carbene (NHC) is a potent organic small-molecule catalyst. However, its high synthetic price and frequent use in combination with excess oxidants have...     

Chemiluminescence detection flow cells for flow injection analysis and high-performance liquid chromatography

We have examined a range of new and previously described flow cells for chemiluminescence detection. The reactions of acidic potassium permanganate with morphine and amoxicillin were used as model systems representing the many fast chemiluminescence reactions between oxidising agents and organic analytes, and the preliminary partial reduction of the reagent was exploited to further increase the rates of reaction. The comparison was then extended to high-performance liquid chromatography separations of α- and β-adrenergic agonists, with permanganate chemiluminescence detection. Flow cells constructed by machining novel channel designs into white polymer materials (sealed with transparent films or plates) have enabled improvements in mixing efficiency and overall transmission of light to the photodetector.     

Chemiluminescence method with potassium permanganate for the determination of organic pollutants in seawater.

A chemiluminescence method with potassium permanganate was developed for use as an indicator of organic pollutants in fresh water. This method could be applied to the determination of organic pollutants in seawater as well. However, the flow chemiluminescence method suffered from the interference of chloride ions at the same concentration of seawater because of the production of manganese dioxide in the oxidation of chloride ions with permanganate. The conditions (concentrations of potassium permanganate and sulfuric acid and sample volume, i.e. flow injection method) were chosen to minimize the interference of chloride ions. The chemiluminescence method shows a good correlation with the chemical oxygen demand method on fresh water added artificial sea salt and seawater samples. Natural seawater was analyzed by the chemiluminescence method. The results obtained were compared with those obtained by chemical oxygen demand under the alkaline condition and total organic carbon methods. The chemiluminescence method has higher sensitivity and reproducibility than the conventional chemical oxygen demand and total organic carbon methods.     

离子液体中Mn（Salen）催化仲醇的氧化反应研究

以PhI(OAc)2为氧化剂,考察了1,3-二烷基咪唑硫酸酯系列离子液体中Mn(Salen)催化仲醇氧化的反应. 结果表明, 在MMISM-CH2Cl2(1:4,v:v)混合溶剂中, 反应条件为n((-苯乙醇): n(醋酸碘苯): n(催化剂1c)=50: 70: 1时, (-苯乙醇的转化率可以达到97.8%, 产物苯乙酮的选择性为100%, 远高于在纯CH2Cl2中的结果, 也要好于[bmim]BF4和[bmim]PF6对该反应的促进作用. 此外, BMISM及BEISE对催化剂1c有较好的稳定作用,催化剂可以重复使用.     

New layered double hydroxides containing intercalated manganese oxide species: synthesis and characterization

Manganese oxide species (MnO(x)) have been intercalated within the gallery spaces of Mg-Al layered double hydroxides (LDHs). Synthesis of these materials was achieved by ion-exchange of the LDH-nitrate precursor with permanganate anion followed by reduction with organic reagents, such as glucose, ethanol, and ascorbic acid. Elemental analysis, X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, HR-TEM, and N(2) sorption analyses have been used to characterize these materials. TEM micrographs of LDH-MnO(x) materials revealed platelike morphology, characteristic of hydrotalcite-like compounds. Chemical analysis results showed that permanganate anions exchanged with nitrate anions. FT-IR and Raman spectroscopy confirmed the reduction of the permanganate anions after treatment with the organic reagents. The XRD diffraction patterns of LDH-MnO(x) revealed that the layer structure is maintained after all synthetic steps. The observed basal spacings of intercalates varied depending on the reducing agent; the largest expansion was 9.93A, corresponding to the use of ascorbic acid. The specific surface areas were also affected according to the organic reagent used, indicating that the structural modifications in the interlayer domain observed by X-ray diffraction also influence the microtextural properties.     

Photoredox-Catalyzed Decarboxylative Bromination,Chlorination and Thiocyanation Using Inorganic Salts

Decarboxylative halogenation reactions of alkyl carboxylic acids are highly valuable reactions for the synthesis of structurally diverse alkyl halides. However, many reported protocols rely on stoichiometric strong oxidants or highly electrophilic halogenating agents. Herein, we describe visible-light photoredox-catalyzed decarboxylative halogenation reactions of N-hydroxyphthalimide-activated carboxylic acids that avoid stoichiometric oxidants and use inexpensive inorganic halide salts as the halogenating agents. Bromination with lithium bromide proceeds under simple, transition-metal-free conditions using an organic photoredox catalyst and no other additives, whereas dual photoredox-copper catalysis is required for chlorination with lithium chloride. The mild conditions display excellent functional-group tolerance, which is demonstrated through the transformation of a diverse range of structurally complex carboxylic acid containing natural products into the corresponding alkyl bromides and chlorides. In addition, we show the generality of the dual photoredox-copper-catalyzed decarboxylative functionalization with inorganic salts by extension to thiocyanation with potassium thiocyanide, which was applied to the synthesis of complex alkyl thiocyanates.     

Unusual Inherent Electrochemistry of Graphene Oxides Prepared Using Permanganate Oxidants

Graphene and graphene oxides are materials of significant interest in electrochemical devices such as supercapacitors, batteries, fuel cells, and sensors. Graphene oxides and reduced graphenes are typically prepared by oxidizing graphite in strong mineral acid mixtures with chlorate (Staudenmaier, Hofmann) or permanganate (Hummers, Tour) oxidants. Herein, we reveal that graphene oxides pose inherent electrochemistry, that is, they can be oxidized or reduced at relatively mild potentials (within the range ±1 V) that are lower than typical battery potentials. This inherent electrochemistry of graphene differs dramatically from that of the used oxidants. Graphene oxides prepared using chlorate exhibit chemically irreversible reductions, whereas graphene oxides prepared through permanganate‐based methods exhibit very unusual inherent chemically reversible electrochemistry of oxygen‐containing groups. Insight into the electrochemical behaviour was obtained through cyclic voltammetry, chronoamperometry, and X‐ray photoelectron spectroscopy experiments. Our findings are of extreme importance for the electrochemistry community as they reveal that electrode materials undergo cyclic changes in charge/discharge cycles, which has strong implications for energy‐storage and sensing devices.     

Evidence for a one-electron mechanistic regime in dirhodium-catalyzed intermolecular C-H amination

Swift and energy efficient conversion of chemical feedstocks to pharmaceuticals and agrochemicals requires the development of new methods to add nitrogen functionality to unfunctionalized organic substrates. Dirhodium-catalyzed insertion of nitrene species into C-H bonds is a promising new method, the main drawback of which is the currently limited understanding of the catalytic mechanism. Herein, cyclic voltammetry and controlled potential electrolysis measurements have enabled us to solve many of the mechanistic mysteries of intermolecular C-H amination catalyzed by [Rh(2)(esp)(2)] (esp=α,α,α',α'-tetramethyl-1,3-benzenedipropanoate). The primary result is that, in addition to a simple nitrene-transfer mechanism that dominates the early stages of the reaction, another mechanism is available that relies on sequential proton-coupled electron transfer steps. Whereas the nitrene-transfer mechanism requires the use of expensive, atom-inefficient oxidants, we show that simple one-electron oxidants such as Ce(4+) may be used to achieve catalytic C-H amination via the one-electron mechanistic regime.