A Regioselective Approach to C3-Aroylcoumarins via Cobalt-Catalyzed­ C(sp2)–H Activation Carbonylation of Coumarins

A new cobalt-catalyzed C–H bond activation of coumarins with aryl halides or pseudohalides and carbon monoxide insertion to give various 3-aroylcoumarin derivatives is described. It is the first time that CO as C1 feedstock is used as the coupling partners in cobalt-catalyzed regioselective coumarin C–H functionalization reactions. Upon activation with manganese powder, the Co catalyzes the C–H bond activation carbonylation reactions of aryl iodides, bromides, and even triflates under mild conditions, providing the regioselective aroylated products in moderate to good yields.

Self-propagating high-temperature synthesis of (Al–2%Mn)–10%TiC and (Al–5%Cu–2%Mn)–10%TiC nanostructured composite alloys when doped with manganese powder

The paper studies the effect of doping with manganese powder on the production of (Al–2%Mn)–10%TiC and (Al–5%Cu– 2%Mn)–10%TiC nanostructured composite alloys by self-propagating high-temperature synthesis (SHS) of TiC titanium carbide nanoparticles from Ti + C charge in the melt of matrix alloys. First, manganese metal powder was added to the matrix bases of Al and Al–5%Cu composite alloys in the amount of 2 wt%. This improved aluminum base tensile strength from 81 MPa (for the original A7 grade aluminum) to 136 MPa and aluminum-copper base tensile strength to 169 MPa. It was found that when aluminum was doped with manganese only, the SHS reaction proceeded weakly and not completely, and the carbide phase size in the resulting alloy (Al–2%Mn)–10%TiC varied from nanoscale to several micrometers. When 10% Na2TiF6halide salt was added to the SHS charge, the SHS process intensified, but the resulting alloy contained a considerable amount of pores, inclusions of unreacted charge and large agglomerates of TiC ceramic nanosized particles. Similar results were obtained in cases of using Ti + C and Ti + C + 10%Na2TiF6SHS charges, but with joint doping of matrix aluminum with copper and manganese, providing more uniform distribution of the TiC nanodispersed phase. The best results were obtained by reducing the Na2TiF6salt additive to 5 % of the SHS charge mass, which facilitated smoother and complete synthesis of predominantly TiC nanosized particles and the formation of a non-porous uniform microstructure of (Al–5%Cu–2%Mn)–10%TiC composite alloy with an ultimate tensile strength of 213 MPa and 6,6 % elongation.

Morphology Evolution of Mn-Si Composition Gradient Micro/Nanomaterials Prepared by Oxygen Assisted Chemical Vapor Deposition

The micro/nanostructure of manganese silicide (Mn-Si) compounds with various morphologies (nanowires, films, particles, and polyhedron shape structure) has been synthesized through oxygen assisted chemical vapor deposition by changing the stacking geometry of manganese powder. Polyhedrons prepared in the Mn-Si contact area were identified to be chemical composition gradient functionally graded materials which were verified by analyzing atomic ratio of Mn/Si from top to bottom. Evolution of morphology greatly depended on the stacking shape correlated distance from precursor to the substrate, resulting in distinctive growth mechanisms. Main structures on the substrate have been verified to be Mn5Si3 and Mn4Si7 with different Mn stacking in bumps comparing to sole Mn4Si7 with flat surface.

The Effect of Corrosion in Hank's Solution on the Bending Stiffness of Bars from Sintered Iron-Manganese Alloys

Fe-Mn alloys represent promising degradable biomaterials for temporary implants. To investigate the effect of corrosion on their mechanical properties, iron powders were mixed with 25, 30 and 35 wt.% of a manganese powder, compressed into prismatic bars and sintered. Sintered bars were immersed in Hank's solution for 8 weeks. The bending stiffness of each bar before and after its exposure to electrolyte was examined. The higher the porosity of a bar was, the higher relative reduction in bending stiffness the bar exhibited. A likely explanation was that in a more porous bar Hank’s solution penetrated deeper and affected larger volume fraction of bar’s material.

Preparation of a New Fracture Ceramic Proppant

A new fracture ceramic proppant was prepared using the low-cost raw bauxite mineral as raw material, by adding the auxiliary material such as potash feldspar, manganese powder and nanocalcium carbonate. The obtained proppants were characterized by XRD and SEM. The crushing rate, particle size, sphericity and roundness of the products were satisfied the recommendation in the standard of the American Petroleum Institute APIR-60.

Hexakis(dimethylformamide-κO)manganese(II) (dimethylformamide-κO)pentakis(thiocyanato-κN)chromate(III)

The title compound, [Mn(C3H7NO)6][Cr(NCS)5(C3H7NO)], was obtained unintentionally as a product of an attempted synthesis of heterometallic complexes based on Reineckes anion using manganese powder, Reineckes salt and 1-(2-hydroxyethyl)tetrazole as starting materials. The crystal structure of the complex consists of an [Mn(dmf)6]2+ cation and a [Cr(NCS)5(dmf)]2− anion (dmf = dimethylformamide). The MnII and CrIII atoms show a slightly distorted octahedral MnO6 and CrN5O coordination geometries with adjacent angles in the range 85.29 (13)–95.96 (14)°.