Active Manganese Dioxide Research Articles

Additional research into arsenic (III) effective catalytic oxidation in an aqueous solution on a new calcium doped active manganese dioxide in a flow column

Additional research into arsenic (III) effective catalytic oxidation in an aqueous solution on a new calcium doped active manganese dioxide in a flow column

Research into arsenic (III) effective catalytic oxidation in an aqueous solution on a new active manganese dioxide in a flow column

Groundwater in many places on Earth contains arsenic compounds. Arsenic (III) compounds must be oxidised to purify water containing arsenic effectively. The subject of this study is oxidation of arsenic (III) compounds in an aqueous solution. Today’s most common industrial arsenic oxidation method using aggressive oxidising agents such as chlorine or ozone has a number of serious disadvantages. The most problematic of these include extremely high risks to human health and the environment, the cost and overall complexity of the process. Catalytic oxidation of arsenic (III) compounds using atmospheric oxygen is an alternative free from the above disadvantages, yet, to date, no information about effective catalysts for this process has been presented in the literature. The arsenic (III) catalytic oxidation process is studied in an aqueous solution on a new active manganese dioxide (NAMD) synthesised by the author. A comparative experimental analysis is performed with other known modifications of manganese dioxide. It is shown that the new active manganese dioxide (NAMD) has high catalytic activity towards arsenic (III), this being confirmed experimentally in both a limited volume and a flow column mode. Some theoretical aspects of the mechanism for catalytic oxidation of arsenic (III) with oxygen on active manganese dioxide in an aqueous solution are also discussed on the basis of the research results. Experimental work is required at pilot plants in the field for successful industrial implementation of the technology for catalytic oxidation of arsenic (III) compounds on NAMD. Further laboratory research is necessary for developing a detailed theoretical basis for catalytic oxidation of arsenic in aqueous solutions. The results of this research are of interest to industrial companies specialising in removing arsenic compounds from water, to scientists and researchers studying catalytic oxidation of arsenic (III), as well as heterogeneous catalytic oxidation with oxygen in general.

Reaction of 2-Aminobenzyl Alcohols with β-Dicarbonyl Compounds to Synthesize Quinoline Derivatives in Water Promoted by Active Manganese Dioxide

Reaction of 2-Aminobenzyl Alcohols with <i>β</i>-Dicarbonyl Compounds to Synthesize Quinoline Derivatives in Water Promoted by Active Manganese Dioxide

Construction of Lithium-Rich Manganese-Based Cathodes Based on Activated Manganese Dioxide for Enhanced Energy Storage Performances

Herein, highly active manganese dioxide is prepared by roasting-disproportionation treatment to fabricate a lithium-rich manganese-based cathode (Li1.6Mn0.6Ni0.3Co0.1O2.6) for enhanced charge/discharge capacity performance. The findings display that the roasting temperature and subsequent disproportionation degree significantly affect crystalline structure of manganese dioxide, thereby apparently improving the electrochemical performances of lithium-rich manganese-based cathodes. When the roasting temperature is 600 °C, the content of α-MnO2 reaches to 69.3% in lithium-rich manganese-based cathode, resulting in the best electrochemical activity. The prepared lithium-rich cathode material displays a discharge capacity of 243 mAh/g after 100 cycles at 0.2 C, and 155 mAh/g at 3 C, which shows good multiplicative performance.

Construction of Lithium-Rich Manganese-Based Cathodes Based on Activated Manganese Dioxide for Enhanced Energy Storage Performances

Construction of Lithium-Rich Manganese-Based Cathodes Based on Activated Manganese Dioxide for Enhanced Energy Storage Performances

A Universal Voltage Design for Triggering Manganese Dioxide Defects Construction to Significantly Boost the Pseudocapacitance

AbstractElectrochemical activation can be appropriate for constructing tunable/controllable defects within the interior of electrode materials. However, the activation mechanisms under different applied electric fields urgently need to be systematically explored. Herein, the electrochemically activated manganese dioxide (MnO2) samples are prepared via applying a positive/negative electric field, and two different activation mechanisms are revealed through a series of characterization methods. During the activation process, it is fascinating to discover that MnO2 mainly generates the O vacancies under positive voltage, whereas the electrolyte cations are embedded in the interlayer under negative voltage. The generated O vacancies and intercalated ions not only act as active sites or participate in the charge‐transport process, but also enhance the transmission capability of carriers. In contrast, the specific capacitances of optimized MnO2 samples are 2.9 and 2.8 times than that of pure‐MnO2 after electrochemical activation under positive and negative voltage, respectively. In addition, the activated samples exhibit excellent cycle stability and resistance to electrochemical corrosion, which can well‐maintain the 3D network structure composed of nanosheets after 5000 cycles. This strategy opens up a promising approach for exploring efficient and corrosion‐resistant electrode materials.

Green and selective oxidation of alcohols using MnO2 nanoparticles under solvent-free condition using microwave irradiation

Alcohols are selectively oxidized to aldehydes using active manganese dioxide (MnO2) nanoparticles under solvent-free condition using microwave irradiation. The complete conversion of the alcohols to their corresponding aldehydes was achieved successfully within only 15 seconds of irradiation in microwave oven. The products of oxidation were characterized by TLC, IR, and Tollens' test, which showed the characteristic results of the desired aldehydes. This method is found to be fast, green, and a very easy procedure that could be applied for the oxidation of alcohols to aldehydes without further oxidation to carboxylic acids.

Highly Active Manganese Dioxide Catalyzed the Construction of S-S Bond

Highly Active Manganese Dioxide Catalyzed the Construction of S-S Bond

Effect of preparation methods on morphology of active manganese dioxide and 2,4-dinitrophenol adsorption performance

Herein active manganese dioxide was prepared by different methods using KMnO4 and MnSO4·H2O as inorganic precursors. The impact of preparation methods on morphology and adsorption performance of the synthesized products was investigated. The experimental results show that the reaction temperature and pressure had a great effect on the morphology and adsorption performance of active manganese dioxide. The shape of active manganese dioxide prepared at room temperature and pressure was short rod-like while active manganese dioxide synthesized by hydrothermal method was mesoporous fibers and had better adsorption performance. The adsorption behavior of 2,4-dinitrophenol on mesoporous manganese dioxide was well described by Langmuir and Freundlich isotherm equation ( R2&gt;0.99) and pseudo-second-order kinetic equation ( R2&gt;0.99), so the adsorption process maybe a chemical and monolayer adsorption. The pH of solution had significant effect on the adsorption performance of 2,4-dinitrophenol on mesoporous manganese dioxide. The adsorption capacity was 2.539 mg/g in the condition of pH = 7.

Synthesis of glucuronic acid by heterogeneous selective oxidation with active MnO2 characterized generally

Active manganese dioxide was prepared and applied in the synthesis of glucuronic acid by selective oxidation from methyl glucoside. The active manganese dioxide was characterized by XPS, XRD, SEM, TGA and N2 adsorption–desorption test. The selective oxidation of methyl glucoside to glucuronic acid is studied with active manganese dioxide under the microwave radiation circumstance in different reaction conditions. The results show that active manganese dioxide displays a good oxidizability and selectivity under the microwave radiation. When methyl glucoside and active manganese dioxide react in a ratio of one to four at 80 °C for 2 h, glucuronic acid reached the highest yield to be 79 %.

Synthesis of 3,3-diphenyl-3H-pyrazoles applying vinyl sulfones as chemical equivalents of acetylenes in reaction of 1,3-dipolar cycloaddition to diphenyldiazomethane

Vinyl phenyl sulfone, methyl (E)-3-(phenylsulfonyl)- and methyl (E)-3-(p-tosyl)acrylates, (E)-3-(phenylsulfonyl)- and (E)-3-(p-tosyl)acrylonitriles react in ethyl ether at 20°C with diphenyldiazomethane leading to the formation of the corresponding 5,5-diphenyl-3-(arylsulfonyl)- Δ2-pyrazolines. Products containing a methoxycarbonyl or cyano group at treating with DBU in dichloromethane at 0°C suffer a dehydrosulfonation and are converted into 4-substituted 3,3-diphenyl-3H-pyrazoles. The oxidation of the mentioned Δ2-pyrazolines with activated manganese dioxide in benzene at 20°C leads to the formation of 4-methoxycarbonyl- and 4-cyano-substituted 5-arylsulfonyl- 3,3-diphenyl-3H-pyrazoles respectively. The reactions of α-bromovinyl phenyl sulfones and a-bromovinyl methyl sulfones with diphenyldiazomethane afforded the corresponding 3-bromo- 5,5-diphenyl-3-sulfonyl-Δ1-pyrazolines. The first among them at 20°C suffered spontaneous elimination of molecular nitrogen and converted into 1-bromo-2,2-diphenyl-1-(phenylsulfonyl)cyclopropane whose structure was established by X-ray diffraction analysis. The action of DBU on another Δ1-pyrazoline resulted in the formation of the product of the Ramberg–Backlund reaction, 5-methylene-3,3-diphenyl-Δ1- pyrazoline together with the product of hydrodebromination–isomerization, 5,5-diphenyl-3-(methylsulfonyl)- Δ2-pyrazoline.

ChemInform Abstract: An Economical and Environmentally Friendly Oxidative Biaryl Coupling Promoted by Activated MnO2.

An activated manganese dioxide (MnO2)–BF3·OEt2 oxidation system was developed to efficiently mediate the intramolecular as well as intermolecular biaryl coupling. The oxidative coupling proceeds smoothly at ambient temperature to deliver the corresponding five- to eight-membered tricyclic products in good to excellent yields. The employment of the combination of MnO2 and BF3·OEt2 is attractive on the basis of economical and environmental issues.

An economical and environmentally friendly oxidative biaryl coupling promoted by activated MnO2.

An activated manganese dioxide (MnO2)-BF3·OEt2 oxidation system was developed to efficiently mediate the intramolecular as well as intermolecular biaryl coupling. The oxidative coupling proceeds smoothly at ambient temperature to deliver the corresponding five- to eight-membered tricyclic products in good to excellent yields. The employment of the combination of MnO2 and BF3·OEt2 is attractive on the basis of economical and environmental issues.

Aerobic Selective Oxidation of Biomass-derived 5-Hydroxymethylfurfural to 2,5-Diformylfuran with Active Manganese Dioxide Catalyst

5-hydroxymethylfurfural (HMF) is an important bio-based platform chemical, and its aerobic selective oxidation to 2,5-diformylfuran (DFF) still remains a challenge. This work dealt with active manganese dioxide (AMD) and efficiently catalyzed HMF oxidation to DFF with a yield of ~73% at 393 K and 60 bar O2 in N,N-Dimethylformamide (DMF). Through analysis of liquid products and the catalyst characterization using X-ray diffraction (XRD), a scanning electron microscope (SEM), a transmission electron microscope (TEM), and an elemental analyzer, it can be seen that this AMD catalyst is a low-cost, efficient, and environmentally benign heterogeneous catalyst for the aerobic selective oxidation of HMF to DFF in a one-pot technique. These research results may provide guidance for the development of more efficient catalysts for the future industrial production of high-value added DFF.

A simple synthetic approach for the transformation of (S)-Ugi's amine

A simple synthetic approach for the transformation of (S)-Ugi's amine, another configuration of (R)-Ugi's amine, one of the most widely used intermediate in the preparation of chiral ferrocene-based ligands, has been developed via esterification using anhydride, alkaline hydrolysis and active manganese dioxide oxidation, and the corresponding ferrocenyl ketone was afforded in good yields.

Kinetics Analysis and Dosage Effects of Manganese Dioxide Adsorbent on Desulphurization of Crude Oil

Environmental regulations all over the world are becoming more restrictive concerning the release of atmospheric pollutants associated with the flue gases of combustion systems, particularly the emission of sulphur dioxide SO2. Hence, the need for producers to improve their existing technology and to start considering alternative means of isolating sulphur from fuels has become incumbent. Adsorptive desulphurization of crude oil was investigated using activated manganese dioxide, AM in batch reactor. Results showed that desulphurization efficiency was increased on increasing contact time and sorbent dose. There was 49% reduction of crude oil sulphur content after the process. The respective R2 value of pseudo-first order and pseudo-second order reaction model were 0.8162 and 0.9951 when the experimental data were fitted into them. Thus, pseudo-second-order reaction model better described the desulphurization process with chemisorptions being the rate limiting step. However, there is need to improve on methods and adsorbents that will result in complete removal of sulphur from crude oil. Also, the effects of desulphurization on other physico-chemical properties of crude oil should be examined for future research work.

ChemInform Abstract: Active Manganese Dioxide Promoted Cyclization of ortho‐(1H‐Pyrrol‐1‐yl)aryl and Heteroaryl Carboxylic Acids to 5H‐Pyrrolo[1,2‐a][3,1]benzoxazin‐5‐one Derivatives.

Abstract The hitherto unknown lactone 5 H -pyrrolo[1,2- a ][3,1]benzoxazin-5-one and six of its substituted derivatives have been prepared by active manganese dioxide promoted oxidative cyclization of the corresponding 2-(1 H -pyrrol-1-yl)benzoic acids, under mild conditions, in moderate yields. The method was successfully extended to the cyclization of some ortho -(1 H -pyrrol-1-yl)heteroaryl carboxylic acids and 2-(1 H -indol-1-yl)benzoic acids.

Active manganese dioxide promoted cyclization of ortho-(1H-pyrrol-1-yl)aryl and heteroaryl carboxylic acids to 5H-pyrrolo[1,2-a][3,1]benzoxazin-5-one derivatives

The hitherto unknown lactone 5H-pyrrolo[1,2-a][3,1]benzoxazin-5-one and six of its substituted derivatives have been prepared by active manganese dioxide promoted oxidative cyclization of the corresponding 2-(1H-pyrrol-1-yl)benzoic acids, under mild conditions, in moderate yields. The method was successfully extended to the cyclization of some ortho-(1H-pyrrol-1-yl)heteroaryl carboxylic acids and 2-(1H-indol-1-yl)benzoic acids.

Synthetic transformations of higher terpenoids. XXVII.* Synthesis of 7-hydroxylabdanoids and their transformations

Allylic oxidation of phlomisoic acid and its methyl ester by selenium dioxide occurred stereoselectively to form 7α-hydroxy derivatives of labdanoids, which were oxidized by active manganese dioxide to 7-ketofuranolabdanoids. Oximation of the last by hydroxylamine hydrochloride in MeOH in the presence of NaOAc gave pure (E)-ketooximes. Beckmann rearrangement of 7-ketooximes of phlomisoic acid and its methyl ester occurred with formation of the corresponding octahydro-1 H-benzoazepines.

Synthesis of boron/nitrogen substituted carbons for aqueous asymmetric capacitors

Boron/nitrogen substituted carbons were synthesized by co-pyrolysis of polyborazylene/coal tar pitch blends to yield a carbon with a boron and nitrogen content of 14 at% and 10 at%, respectively. The presence of heteroatoms in these carbons shifted the hydrogen evolution overpotential to −1.4 V vs Ag/AgCl in aqueous electrolytes, providing a large electrochemical potential window (∼2.4 V) as well as a specific capacitance of 0.6 F/m 2. An asymmetric capacitor was fabricated using the as-prepared low surface area carbon as the negative electrode along with a redox active manganese dioxide as the positive electrode. The energy density of the capacitor exceeded 10 Wh/kg at a power density of 1 kW/kg and had a cycle life greater than 1000 cycles.