The first example of a base metal (manganese) catalyzed acceptorless dehydrogenative coupling of methanol and amines to form formamides is reported herein. The novel pincer complex ...(iPr‐PNHP)Mn(H)(CO)2 catalyzes the reaction under mild conditions in the absence of any additives, bases, or hydrogen acceptors. Mechanistic insight based on the observation of an intermediate and DFT calculations is also provided.
Back to basics: An acceptorless dehydrogenative coupling of methanol and amines to form formamides that is catalyzed by a well‐defined manganese pincer complex (see scheme) is reported. Mechanistic insight based on the observation of an intermediate and density functional calculations is also provided.
A manganese‐catalyzed regio‐ and stereoselective hydroarylation of allenes is reported. The C−H functionalization method provides access to various alkenylated indoles in excellent yields. Moreover, ...a hydroarylation/cyclization cascade involving an unexpected C−N bond cleavage and aryl shift has been developed, which provides a new synthetic approach to substituted pyrroloindolones.
Which way to go: An efficient, scalable, regio‐, and stereoselective manganese‐catalyzed C−H arylation of allenes is reported. When trisubstituted allenes are used, a C−H functionalization/C−N bond cleavage/cyclization cascade affords pyrroloindolones. Mechanistic studies suggest that a manganacycle is formed during the catalytic cycle.
Nitrogen-doped porous hollow carbon spheres were fabricated via hydrothermal pre-carbonization and pyrolysis carbonization using yeast cell templates. After that, the MnO2 nanowires were deposited by ...the in-situ hydrothermal reaction. By controlling the reaction concentration, various MnO2 nanostructures with different morphologies and electrochemical properties were obtained. The as-prepared sample exhibited an ultrahigh specific capacitance of 255 F g-1 at a current density 1 A g-1 in 1 M Na2SO4 electrolyte. The MnO2/HCS-30 material was used as the positive electrode, and the HCS was used as the negative electrode to assemble the asymmetric supercapacitor. The maximum energy density operating at the 2.0 V voltage window is 41.4 Wh kg−1 at a power density of 500 W kg−1 and still maintains 23.0 Wh kg−1 at a power density of 7901 W kg−1. Moreover, it displayed excellent cycle stability, retained approximately 93.9% of the capacitance after 5000 cycles. This work innovatively combines biomass and energy, provides an environmentally benign strategy and new insights for the preparation of electrode materials.
An asymmetric supercapacitors based on MnO2@Biological cell template synthesized nitrogen-doped porous hollow carbon spherical composites exhibited high energy and power density and an excellent cycle stability. Display omitted
•N-doped porous hollow carbon spheres were synthesized based on yeast templates.•The MnO2 nanowires were anchored by one-step hydrothermal deposition.•The prepared composite material exhibited a unique hollow structure.•As-prepared asymmetric supercapacitors exhibited excellent capacitive behavior.
The first manganese‐catalyzed hydrogenation of esters to alcohols has been developed. The combination of Mn(CO)5Br with HN(CH2CH2P(Et)2)2 leads to a mixture of cationic and neutral Mn PNP pincer ...complexes, which enable the reduction of various ester substrates, including aromatic and aliphatic esters as well as diesters and lactones. Notably, related pincer complexes with isopropyl or cyclohexyl substituents showed very low activity.
A manganese‐catalyzed hydrogenation of esters to alcohols has been developed. The combination of Mn(CO)5Br with HN(CH2CH2P(Et)2)2 led to a cationic and a neutral Mn PNP pincer complex, which both enable the reduction of various aromatic and aliphatic esters as well as diesters and lactones.
The sustainable use of the resources on our planet is essential. Noble metals are very rare and are diversely used in key technologies, such as catalysis. Manganese is the third most abundant ...transition metal of the Earth's crust and based on the recently discovered impressive reactivity in hydrogenation and dehydrogenation reactions, is a potentially useful noble‐metal “replacement”. The hope of novel selectivity profiles, not possible with noble metals, is also an aim of such a “replacement”. The reactivity of manganese complexes in (de)hydrogenation reactions was demonstrated for the first time in 2016. Herein, we summarize the work that has been published since then and especially discuss the importance of homogeneous manganese catalysts in comparison to cobalt and iron catalysts.
A latecomer worth waiting for: In the last two years manganese complexes have been identified as highly active catalysts for diverse hydrogenation and dehydrogenation reactions. The results in this field are summarized and discussed and compared to iron and cobalt catalysts.
A new hydrogenation catalyst based on a manganese complex of a chiral P,N,N ligand has been found to be especially active for the hydrogenation of esters down to 0.1 mol % catalyst loading, and gives ...up to 97 % ee in the hydrogenation of pro‐chiral deactivated ketones at 30–50 °C.
Non‐precious metal for valuable catalysis: A new manganese catalyst for enantioselective ketone hydrogenation has been developed (see scheme). This catalyst also hydrogenates esters at low catalyst loadings for an earth‐abundant metal system.
Electron donors for autotrophic denitrification Di Capua, Francesco; Pirozzi, Francesco; Lens, Piet N.L. ...
Chemical engineering journal (Lausanne, Switzerland : 1996),
04/2019, Letnik:
362
Journal Article
Recenzirano
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•Twelve electron donors for autotrophic denitrification are critically reviewed.•Biochemical aspects and microbiology of autotrophic denitrification are discussed.•Novel insights on ...the use of inorganic compounds for denitrification are presented.•Applications, cost and environmental impact of inorganic compounds are compared.•Criteria and guidelines for electron donor selection are provided.
Autotrophic denitrification (AuDen) is an efficient, convenient and eco-friendly biological process for the treatment of nitrate-contaminated organic-deficient waters. AuDen can be applied as a unique process or complement the conventional denitrification with organics, reducing the risk of organic carbon breakthrough in the effluent and formation of undesirable byproducts downstream (e.g. trihalomethanes). A wide range of inorganic compounds can act as electron donors for AuDen. The most used electron donors include hydrogen gas and reduced sulfur compounds, i.e. elemental sulfur, sulfide and thiosulfate. Recently, the denitrification potential of certain contaminants (such as sulfite, thiocyanate, arsenite and manganese) and inorganic wastes (such as biogenic elemental sulfur from biogas upgrading) has been revealed and attracted interest for developing technologies that combine nitrate removal with water detoxification. This paper critically reviews the state of the art of the most used electron donors for AuDen and highlights recent advances on the application of novel inorganic compounds, reactor configurations and microorganisms to support denitrification. Criteria and guidelines for the selection of a suitable electron donor are provided.
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•Highly stable nZVMn was synthesized by chemical reduction method.•Addition of S2O82− promoted the performance of nZVMn.•Second-order rate constants of CIP with OH and SO4− were ...calculated.•Proposed pathways for conversion of CIP into TPs were developed.•Acute and chronic toxicities of CIP and its TPs were evaluated.
Nano zerovalent manganese (nZVMn, Mn0) materials have been synthesized in this study and used for degradation of ciprofloxacin (CIP), an emerging water pollutant. The investigation of physiological characteristics of Mn0 by different characterization techniques proved successful formation of Mn0 by the chemical reduction method and found it to be highly crystalline. The Mn0 was highly efficient and resulted in 63% degradation of CIP using CIP0 = 10 mg/L and Mn00 = 1.0 g/L at a reaction time of 80 min. Addition of S2O82− to Mn0 promoted removal efficiency of CIP from 63 to 95% at a reaction time of 80 min using the conditions of CIP0 = 10 mg/L, Mn00 = 1.0 g/L, and S2O82−0 = 50 mg/L. The presence of OH and SO4− scavengers inhibited the degradation of CIP by Mn0/S2O82−. The comparable second-order rate constants of CIP with OH and SO4− were calculated to be 2.35 × 109 and 2.10 × 109 M−1 s−1, respectively. High S2O82− and Mn0 concentrations and low pH accelerated the degradation of CIP. However, removal efficiency of CIP by Mn0 with the added S2O82− was inhibited using high CIP concentration, high pH, inorganic anions, and NOM. Degradation pathways from OH and SO4− based degradation of CIP were developed. Acute and chronic toxicities of CIP and its products were estimated, showing the final product to be non-toxic. The as-synthesized Mn0 was found to be stable as well as environmentally friendly for treating CIP. This study suggests that Mn0 with the added S2O82− is a promising alternative for potential remediation and detoxification of CIP and other emerging water pollutants.
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