Preparation of manganese oxide nanoparticles by thermal decomposition of nanostructured manganese carbonate

MnO and Mn₂O₃ nanoparticles were prepared in air and argon atmosphere by thermal decomposition of nanocrystalline manganese carbonate synthesized by reaction of manganese(II) nitrate with glycerol. Samples were characterized using transmission electron microscopy, simultaneous thermal analysis and X-ray diffraction analysis. Average sizes of prepared nanoparticles were calculated from XRD patterns using Scherrer equation. Also, the conditions for decomposition of manganese carbonate were optimized to obtain optimal nanoparticle sizes. Due to suitable sizes of prepared nanoparticles and the initial material, this method can be used in a wide range of industrial applications.     

Confined growth of lithium manganese oxide nanoparticles

Nanostructures of single crystallites of spinel LiMn₂O₄ (LMO) were prepared by the simple pyrolysis of aqueous solution of LiNO₃ and Mn(NO₃)₂ in a confined space such as either droplets or mesopores. When the mixed nitrate solution was spray pyrolyzed at temperatures below 700 °C, 1-μm LMO spheres were obtained consisting of ~20-nm single crystallites randomly packed. Such LMO phase, once obtained, would sustain for further heat-treatment. Next, new spraying solution was prepared by adding the precursor for mesoporous silica (MPS) to the nitrates solution. By spray pyrolyzing such solution, LMO was impregnated inside pores of the MPS being structured. The silica could be removed by subsequent NaOH treatment to leave spherical LMO mesophase. The nitrates was also able to soak into the existing MPS having cylindrical pores and form short isolated LMO chains in the mesopores by the subsequent heating. After the same NaOH treatment, the LMO phase turned into bundles of very ‘long’, and often straight, chains, consisting of 8-nm LMO nanoparticles. This will be elucidated through further study.     

Regioselective hydrothiolation of terminal acetylene catalyzed by magnetite (Fe3O4) nanoparticles

Herein, we report a new and solvent-free methodology for the preparation of vinyl thioethers from terminal alkynes and thiols, using magnetite (Fe₃O₄) nanoparticles as a recyclable catalyst. With this greener method, the desired vinyl thioethers were achieved in good yields and with good stereoselectivity. In addition, the catalyst was easily recovered using a simple external magnet and reused for further catalytic reactions without significant loss of activity up to the fifth cycle.     

Michael addition of 1,3-dicarbonyl compounds catalyzed by iron oxide nanoparticles

Several iron oxides nanoparticles (Fe₂O₃@Fe₂O₃, Fe°@Fe₂O₃, GO@Fe₂O₃ and calcinated Fe₂O₃) have been assessed as catalysts in the 1,4-addition of a cyclic β-ketoester onto methyl vinyl ketone under neat conditions. It appeared that calcinated Fe₂O₃NP are efficient catalysts at 1?mol% loading for the Michael addition of 1,3-dicarbonyl compounds onto various enones.     

Regioselective protection of sugars catalyzed by dimethyltin dichloride

The first catalytic process for protection of hydroxyl groups in sugars has been developed. Highly regioselective protection was accomplished along with high chemical yield. The regioselectivity of the benzoylation was realized as an intrinsic character of sugars based on a stereorelationship among their hydroxyl groups. Furthermore, complete protection of alpha-methyl glucoside and beta-methyl xyloside was accomplished.     

Regioselective green anomeric deacetylation catalyzed by lanthanide triflates

Lanthanide triflates, especially Nd(OTf)₃, efficiently catalyze the regioselective transesterification of anomeric acetates. This method offers an efficient solution for the otherwise difficult removal of methyl uronates anomeric acetates as well as a green alternative to published protocols since the lanthanide catalysts are non-toxic and may be easily recycled and reused.     

Regioselective acylation of resveratrol catalyzed by lipase under microwave

The enzymatic regioselective acylation of resveratrol was achieved in organic solvents catalyzed by the lipase from Candida sp. 99–125 (CSL) under microwave irradiation. Influences of various reaction conditions have been studied. After selecting the optimum conditions [MTBE (20?ml, a_w?=?0.38), resveratrol (0.1?mmol), vinyl acetate (1.0?mmol) and CSL (100.0?mg) under microwave irradiation (35°C, 400 W)], CSL exhibited a satisfied enzyme activity (281?±?11?μmol/g/h) and yield of 75% for 4′-O-acetyl- resveratrol could be obtained in about 4?h when performing the reaction on a 25-fold-larger scale.

Schematic illustration of the enzymatic regioselective acylation of resveratrol catalyzed by the lipase from Candida sp. 99–125 (CSL) under microwave irradiation.     

Regioselective hydroalumination of unsaturated hydrocarbons by alkylalanes catalyzed by zirconium complexes

Conclusion An effective method has been developed for the preparation of difficultly accessible higher dialkylhaloalanes by hydroalumination of mono-, di-, and tri-olefins of different structures by i-Bu₂AlCl in the presence of Cp₂ZrCl₂.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1089–1095, May, 1987.     

Development of target-specific multimodality imaging agent by using hollow manganese oxide nanoparticles as a platform

A platform protocol developed based on the hollow manganese oxide nanoparticles provided multimodal diagnostic agents, which allow the selectively detect vulva cancer with T(1)-weighted in vivo MRI.     

Regioselective cyclotrimerization of phenylacetylenes to 1,2,4-triarylbenzenes catalyzed by iridium-diphosphine complexes

The organoiridium derivatives HIr(cod)(P-P) (cod=1,5-cyclooctadiene; P-P=dppm (bis(diphenylphosphino)methane), dppe (1,2-bis(diphenylphosphino)ethane), dppp (1,3-bis(diphenylphosphino)propane), dppb (1,4-bis(diphenylphosphino)butane)) catalyze the regioselective cyclotrimerization of phenylacetylene as well as of its derivatives p-CH₃OC₆H₄CCH and p-CF₃C₆H₄CCH. The catalytic activity of the precursors as well as the selectivity towards formation of the 1,2,4-triarylbenzenes (up to 100%) are influenced by the diphosphine, and both increase by decreasing the size of the phosphine-iridium chelate ring.     

Chemiluminescence of luminol catalyzed by silver nanoparticles

Silver nanoparticles (AgNPs) are synthesized by chemical reduction method and characterized by UV-vis spectra, transmission electron microscopy, and high performance particle sizer. We have found that AgNPs could enhance the chemiluminescence (CL) intensity of luminol-H(2)O(2) system. In this reaction, luminol intermediate is generated under alkaline condition on the surface of AgNPs in luminol-H(2)O(2) system and enhances CL intensity. To validate the reaction mechanism, AgNPs are bound with thioglycolic acid (Ag-HSCH(2)COOH) and then joined to BSA protein (Ag-BSA). We investigate the CL intensity in the presence of Ag-HSCH(2)COOH or Ag-BSA comparing with that in the presence of AgNPs and conclude the catalytic reaction take place on the surface of AgNPs.     

Regioselective double hydrophosphination of terminal arylacetylenes catalyzed by an iron complex

The first catalytic double hydrophosphination of alkynes was achieved by reaction with diarylphosphines in the presence of an iron catalyst. The double hydrophosphination proceeded regioselectively and effectively for various secondary arylphosphines and terminal alkynes to give 1,2-bisphosphinoethane derivatives.     

Regioselective alkylation of carbohydrate derivatives catalyzed by a diarylborinic acid derivative

Regioselective, catalyst-controlled monoalkylations of cis-vicinal diol motifs in carbohydrate derivatives, using a diphenylborinic ester precatalyst, are described. Selective installation of benzyl, naphthylmethyl, 4-bromobenzyl and benzyloxymethyl protective groups at a single secondary hydroxy group of ten representative carbohydrate derivatives illustrates the scope of this method. This new mode of catalytic reactivity represents an operationally simple method to access useful monoalkylated building blocks while avoiding the use of stoichiometric quantities of organotin reagents.     

Nickel oxide nanoparticles catalyzed synthesis of poly-substituted quinolines via Friedlander hetero-annulation reaction

Reusable acidic nickel oxide nanoparticles have been synthesized,characterized and applied as a catalyst to convert 2-aminoaryl ketones and β-ketoesters/ketones into the corresponding quinolines in good yields with high selectivity.This could serve as a simple and convenient procedure for the Friedlander annulations.     

Thermal behavior and thermokinetic of double-base propellant catalyzed with magnesium oxide nanoparticles

Journal of Thermal Analysis and Calorimetry - Catalytic effect of magnesium oxide nanoparticles (nano-MgO) on the thermal behavior and decomposition reaction kinetic of the double-base propellant...     

Aromatic amine mediated ring opening of epoxides: A reaction catalyzed by biogenic iron oxide nanoparticles

An efficient green method was used for the synthesis of polyphenol capped iron oxide nanoparticles (ION) from an agro waste, peanut skin. The polyphenol capped ION was characterized by Fourier transformed infra-red (FTIR), Powder XRD and X-ray photoelectron spectroscopic (XPS) analysis. To evaluate the catalytic activities of ION, ring opening of epoxides by aromatic amines has been performed and the catalyst showed good activity with yields up to 90% of the major products using only 20 ​mg of the catalyst under solvent free neat condition at room temperature (28 ​°C) after 5 ​h. These nanoparticles can be reused for three times without significant loss in their activities.     

钴纳米粒子催化水相费托合成

水相费托合成可以在远低于传统温度下实现,其低温高效的特点使其具有重要的应用潜力. 本文制备了水相稳定且可循环利用的Co纳米粒子并应用于水相费托反应,150℃下活性为7.4×10^-7mol_CO g_Co^-1 s^-1,C₅₊选择性接近40%,是目前纯钴水相费托合成的最好结果,而其它方法合成的催化剂在150℃时活性低下. 对催化剂进行了粒径、结构、成分测定和原位红外光谱检测,研究了催化剂在反应中的重构过程和B掺杂效应.     

Regioselective ring cleavage of oxiranes catalyzed by organotin halide - triphenylphosphine complex

Vicinal chloroesters are formed in high yield from the reaction of oxiranes and benzoyl chloride in the presence of organotin halide - triphenylphosphine complex with enhanced regioselectivity in oxirane ring cleavage.