Copper‐Catalyzed Aerobic Formation of Unstable Sulfinyl Radicals for the Synthesis of Sulfinates and Thiosulfonates

Copper‐catalyzed aerobic coupling of thiols and alcohols affords sulfinates and thiosulfonates. These products are assumed to form via sulfinyl radicals which are not commonly found in oxidative coupling reactions of thiols. A reaction mechanism involving sulfinyl radicals is proposed, and mass and electron paramagnetic resonance (EPR) experimental results are provided.

     

Enantioselective Construction of Cyclic Enaminone‐Based 3‐Substituted 3‐Amino‐2‐oxindole Scaffolds via Catalytic Asymmetric Additions of Isatin‐Derived Imines

The first catalytic asymmetric construction of the cyclic enaminone‐based 3‐substituted 3‐amino‐2‐oxindole scaffold with potential bioactivity has been developed via chiral phosphoric acid‐catalyzed enantioselective addition reactions of cyclic enaminones to isatin‐derived imines, which afforded a series of cyclic enaminone‐based 3‐substituted 3‐amino‐2‐oxindoles in high yields and excellent enantioselectivities (up to 99% yield, 97% ee). The investigation of the reaction mechanism suggested that it was facilitated by a dual hydrogen‐bonding activation mode between the two substrates and the chiral phosphoric acid. Besides, this method could be utilized for a large‐scale synthesis with maintained enantioselectivity. This approach will not only offer a useful method for enantioselective construction of the cyclic enaminone‐based 3‐substituted 3‐amino‐2‐oxindole scaffold, but also enrich the research on catalytic asymmetric addition reactions of isatin‐derived imines by using electron‐rich olefins as nucleophiles. More importantly, a preliminary evaluation on the cytotoxicity of some selected products revealed that two of the enantio‐pure compounds exhibited moderate to strong cytotoxicity to A549, 786‐0, ECA109 and BT474 cancer cell lines.

     

Ru/SiO2 Catalyst for Highly Selective Hydrogenation of Dimethyl Malate to 1,2,4-Butanetriol at Low Temperatures in Aqueous Solvent

Catalysis Letters - Catalytic selective hydrogenation of esterified malic acid to produce 1,2,4-butanetriol (1,2,4-BT) using H2 as the reducing reagent suffers from the low 1,2,4-BT selectivity....     

Catalyst-Controlled Selectivity in Oxidation of Olefins: Highly Facile Success to Functionalized Aldehydes and Ketones

Catalysis Letters - The attractive challenge in green chemistry is exploring novel heterogeneous catalyst system for catalyst-controlled product selectivity for oxidation of olefins. Hence, we...     

Correlation of Vibroacoustic Signal with Ceramic Component Wear During Frictional Interaction with a Steel Disc

Refractories and Industrial Ceramics - Complete correlation between dimensions of the wear area on specimens made of oxide-carbide ceramics and the root-mean-square value of vibration acceleration...     

About the Nature of Quasi-Cleavage in Low-Carbon Steel Embrittled with Hydrogen

Metal Science and Heat Treatment - Scanning electron microscopy and confocal laser scanning microscopy are used to study a fracture surface of hydrogen-charged low-carbon steel, which has been...     

Experimental Search for Chemical Compositions of Superelastic Titanium Alloys with Enhanced Functional Properties

Metal Science and Heat Treatment - Ti – Zr-based alloys with a high zirconium content prepared by vacuum-arc remelting with nonconsumable tungsten electrode are studied. The optimum number of...     

Simulation of the Kinetics of Dynamic Recrystallization of Alloy KhN55MBYu-VD During Hot Deformation

Metal Science and Heat Treatment - A facility for physical simulation is used to plot dependences of flow stress on the degree of deformation in the temperature range from 1000 to 1230°C at...     

As-cast microstructure of Al-Zn-Mg-Cu-Zr alloy containing trace amount of Sc

It has been reported that the element scandium(Sc) is the most effective modificator which can significantly refine the grain size, prohibit recrystallization process and increase the strength. Adding trace of Sc in 7000 series aluminum alloys is considered to be an effective way to modify its micros tructure and promote mechanical properties. In order to study the effect of Sc element on ascast microstructure of Al-Zn-Mg-Cu-Zr alloy, ingots containing different amounts of Sc were prepared by ferrous-mold cast. Microstructures were characterized by means of differential scanning calorimeter(DSC), X-ray diffraction(XRD), optical microscope(OM) and scanning electrical microscope(SEM). The results indicate that when the Sc level exceeds a critical concentration,Al_3(Sc,Zr) primary phase would form in the melt and act as an efficient nucleant, resulting in very refined grain and an equiaxed grain structure. Sc element reduces the number of eutectic phases formed during solidification,coupled with an increase in the concentration of major alloying elements retained in the solute. This behavior suggests possible benefits in improving the integrated properties of terminal products.     

Kinetics of the hydrotreatment of rapeseed oil fatty acid triglycerides under mild conditions

To establish principal regularities of the hydrotreatment of rapeseed oil fatty acid triglycerides (FATs), the kinetics of this process has been studied at temperatures of 300–380°C, contact times of 0.38–0.10 h, and a hydrogen pressure of 1.0 MPa in a flow fixed-bed reactor. The process is performed over nonsulfided nickel catalysts, which are of great practical interest for the production of green diesel. The kinetic scheme of the process with consideration for target products (alkanes) and all oxygen-containing by-products has been proposed. The quantitative estimate, which enables the prediction of the composition of products for other process conditions, has been obtained for the principal paths of the hydrotreatment of rapeseed oil FATs.