Degradation Action of the Anaerobic Bacteria and Oxygen to the Polymer

Oxygen could prohibit anaerobic bacterium in the produced water and degrade the polymer molecular chains. Aiming at problems making up aerobic polymer solution by the produced water in Daqing Oil Field, some evaluations were done on the viscosity characteristics of polymer solution and bactericide in anaerobic and aerobic environments. Reasonable aerobic concentration of the produced water was obtained. The experimental results indicate that the viscosity of polymer solution confected by the produced water in the aerobic environment is higher than that of the polymer solution confected by the produced water in the anaerobic environment, and the reasonable aerobic concentration is about 6 mg•L^－1. The bactericide has sterilization ability in anaerobic and aerobic environments, but the sterilization effect is better in the aerobic environment.     

Decarboxylative Benzylation of Aryl and Alkenyl Boronic Esters

The copper‐catalyzed decarboxylative benzylation of aryl and alkenyl boronic esters with electron‐deficient aryl acetates is reported. The oxidative coupling proceeds under mild, aerobic conditions and tolerates a host of potentially reactive electrophilic functional groups that would be problematic with traditional benzylation methods (aryl iodides and bromides, protic heteroatoms, aldehydes, Michael acceptors). A reaction pathway in which a benzylic nucleophile is generated by aryl acetate decarboxylation and in turn is intercepted by the catalyst to form diarylmethane products is supported by mechanistic studies.     

Lewis酸对氮杂环卡宾协同催化体系中反应途径的调控

该研究基于氮杂环卡宾（N-heterocyclic carbene,NHC）新颖的协同催化策略,通过Lewis酸共催化剂调控反应具体途径.从α,β-不饱和醛类化合物出发,立足于多反应位点的高烯醇中间体,与氯化镁协作实现高对映选择性的质子转移历程,构建β-手性酯类产物;在相似的反应体系中与氯化钌协作实现高效的空气氧化,构建α,β-不饱和酯类化合物.这两个迥异的反应途径对底物均有较好的官能团容忍性,以高转化率得到目标产物.     

Thermodynamic study of metabolic reactions in an aqueous protein solution

Summary The time dependences of the thermal power of aqueous myoglobin solutions were measured by microcalorimeter at 298.15 K. Exothermic reactions occurred in aqueous myoglobin solutions due to the metabolism of aerobic microbes, and these roughly consisted of four phases. The generation times obtained were about (55±5) min for the logarithmic exothermal reaction phase. The total energies were considerably dependent on the amount of oxygen present, suggesting strongly that the exothermic reaction was caused by aerobic microbes. The apparent thermal metabolic rates were positively dependent on the concentration of myoglobin, probably because of the effects of myoglobin as a food source and/or as a donor of oxygen.     

Aerobic Oxidation in Nanomicelles of Aryl Alkynes,in Water at Room Temperature

On the basis of the far higher solubility of oxygen gas inside the hydrocarbon core of nanomicelles, metal and peroxide free aerobic oxidation of aryl alkynes to β‐ketosulfones has been achieved in water at room temperature. Many examples are offered that illustrate broad functional group tolerance. The overall process is environmentally friendly, documented by the associated low E Factors.     

Porous chitosan–MnO2 nanohybrid: a green and biodegradable heterogeneous catalyst for aerobic oxidation of alkylarenes and alcohols

A porous chitosan–manganese dioxide (PC–MnO₂) nanohybrid was synthesized using an in situ reduction method, in which potassium permanganate solution and nanoporous chitosan acted as precursor and reducing agent. The chemical and structural properties of PC–MnO₂ were characterized using scanning and transmission electron microscopies, X‐ray diffraction, thermogravimetric analysis and Fourier transform infrared spectroscopy. Highly dispersed MnO₂ nanoparticles in a matrix of porous chitosan showed high catalytic activity for selective aerobic oxidation of alkylarenes and alcohols without using any bases or expensive oxidants. Short reaction time, ease of product separation by filtration and recyclability of the catalyst make it environmentally and economically favoured for the synthesis of versatile aldehydes and ketones. Copyright © 2015 John Wiley & Sons, Ltd.     

Mn(III)‐salan/graphene oxide/magnetite nanocomposite as a highly selective catalyst for aerobic epoxidation of olefins

A nanocomposite was synthesized using carbon‐coated Fe₃O₄ nanoparticle‐decorated reduced graphene oxide as a convenient and efficient supporting material for grafting of a manganese–reduced Schiff base (salan) complex via covalent attachment. The nanocomposite was characterized using X‐ray diffraction, Fourier transform infrared and diffuse reflectance UV–visible spectroscopies, inductively coupled plasma atomic emission spectrometry and scanning electron microscopy. It was evaluated as a catalyst for the aerobic epoxidation of olefins in acetonitrile in combination with a sacrificial co‐reductant (isobutyraldehyde). The catalytic performance of the heterogeneous system of the Mn–salan complex is superior to that of the homogeneous one. The catalyst activity strongly depends on the reaction temperature and nature of the solvent. The epoxide yield increases with the nucleophilic character of the olefin. The nanocomposite performs well as an epoxidation catalyst for electron‐rich and conjugated olefins. It can be recovered from the reaction medium by magnetic decantation and reused, maintaining good catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Oxygen‐Dependent Photocatalytic Water Reduction with a Ruthenium(imidazolium) Chromophore and a Cobaloxime Catalyst

Detailed investigations of a photocatalytic system capable of producing hydrogen under pre‐catalytic aerobic conditions are reported. This system consists of the NHC precursor chromophore [Ru(tbbpy)₂(RR′ip)][PF₆]₃ (abbreviated as Ru(RR′ip)[PF₆]₃; tbbpy=4,4′‐di‐tert‐butyl‐2,2′‐bipyridine, RR′ip=1,3‐disubstituted‐1H‐imidazo[4,5‐f][1,10]phenanthrolinium), the reduction catalyst Co(dmgH)₂ (dmgH=dimethylglyoximato), and the electron donor ascorbic acid (AA). Screening studies with respect to solvent, cobaloxime catalyst, electron donor, pH, and concentrations of the individual components yielded optimized photocatalytic conditions. The system shows high activity based on Ru, with turnover numbers up to 2000 under oxygen‐free and pre‐catalytic aerobic conditions. The turnover frequency in the latter case was even higher than that for the oxygen‐free catalyst system. The Ru complexes show high photostability and their first excited state is primarily located on the RR′ip ligand. X‐ray crystallographic analysis of the rigid cyclophane‐type ligand dd(ip)₂(Br)₂ (dd(ip)₂=1,1′,3,3′‐bis(2,3,5,6‐tetramethyl‐1,4‐phenylene)bis(methylene)bis(1H‐imidazo[4,5‐f][1,10]phenanthrolinium)) and the catalytic activity of its Ru complex [{(tbbpy)₂Ru}₂(μ‐dd(ip)₂)][PF₆]₆ (abbreviated as Ru₂(dd(ip)₂)[PF₆]₆) suggest an intermolecular catalytic cycle.