Search results for "Role"

Aktivitāšu izstrāde nozares angļu valodas apguvei

2019

Lai saglabātu konkurētspēju savā jomā, profesionāļiem ir jāattīsta jomai atbilstošu angļu valodas zināšanu apguve, bet aizvien pieaugošais pieprasījums pēc nozaru angļu valodas apmācībām rada pieprasījumu arī pēc kompetentiem pasniedzējiem un mācību materiāla izstrādātājiem. Šis darbs tika izstrādāts ar mērķi pētīt nozaru angļu valodas mācību materiālu izveides procesu, kā arī, apmācot studentus, radīt oriģinālu mācību materiālu konkrētai Finanšu menedžmenta programmas studentu grupai. Lai izveidotu šo materiālu, tika iegūti kvalitatīvie dati, analizējot nodarbību laikā novērotos procesus. Jaunizveidotais materiāls tika veiksmīgi izmantots praksē.

Selective Acrolein Hydrogenation over Ligand-Protected Gold Clusters : A Venus Flytrap Mechanism

2022

The catalytic partial hydrogenation of α,β-unsaturated aldehydes is an ideal reaction to understand the selectivity between two different functional groups Here the two functional groups are C═C and C═O, and the hydrogenation of C═O is preferentially desired due to the importance of the issuing products, unsaturated alcohols, in fine-chemical industries. Using density functional theory calculations, we investigate the catalytic competency toward this reaction of a Au nanocluster in the presence of protecting ligands that offer higher stability and the possibility for the uniform distribution of size-selected clusters in the catalytic system. meta-Mercaptobenzoic-acid-protected-protected Au …

CCDC 1050035: Experimental Crystal Structure Determination

2015

Related Article: Lucía Piñeiro-López, Zulema Arcís-Castillo, M. Carmen Muñoz, and José A. Real|2014|Cryst.Growth Des.|14|6311|doi:10.1021/cg5010616

ChemInform Abstract: New Porphycene Ligands: Octaethyl- and Etioporphycene (OEPc and EtioPc) - Tetra- and Pentacoordinated Zinc Complexes of OEPc.

2010

Modular one-pot synthesis of tetrasubstituted pyrroles from alpha-(alkylideneamino)nitriles.

2007

2,3,4,5-Tetrasubstituted pyrroles have been prepared with high regioselectivity by a formal cycloaddition of alpha-(alkylideneamino)nitriles and nitroolefins followed by elimination of HCN and HNO2. The reaction allows the convergent construction of the pyrrole ring in four steps from a nitroalkane and three aldehydes.

ChemInform Abstract: Stereoselective Synthesis of 2-Substituted Pyrrolidines.

2000

Using O -pivaloyl protected D-galactopyranosylamine and D-arabinopyranosylamine, ( S ) or ( R ) configured α-substituted homoallylamines are synthesized with high diastereoselectivity by reaction of the corresponding aldimines with allyltributylstannane. Electrophile-induced endo -trig-cyclization of these N -glycosylhomoallylamines gave the 2-substituted pyrrolidines of high diastereomeric purity.

Tungsten oxides as catalysts in selective oxidation

1983

Abstract The reaction of allyl iodide was studied at the surface of four tungsten oxides and molybdenum trioxide. On WO2.95 and MoO3, in which crystallographic shear structures are formed on reduction, acrolein is produced at 300–400 °C, whereas W18O49 and WO2, which do not show this property, are inactive, as is WO3. It is concluded that the transformation of a corner-linked into an edge-linked arrangement of metal-oxygen octahedra provides a facile route for insertion of oxygen into a hydrocarbon molecule.

Synthesis of Lamellarin D Trimethyl Ether and Lamellarin H via 6π-Electrocyclization.

2015

An electrocyclic ring closure of a 2-azapentadienyl anion generated in situ from a chalcone and glycine ester is the key step of an efficient synthesis of the pyrrole core of the lamellarin alkaloids. A recently developed scalable one-pot procedure provides multigram quantities of a 3,5-diaryl-4-iodopyrrole-2-carboxylate intermediate which is transformed in four further high-yielding operations including a one-pot Pomeranz–Fritsch alkylation/cyclization and an Ullmann-type lactone ring closure into the pentacyclic lamellarin skeleton.

Free radical scavenging capability, antioxidant activity and chemical constituents of Pyrola incarnata Fisch. leaves

2013

Abstract In the present study, the crude extract and its four fractions of petroleum ether, ethyl acetate, n-butanol, water from Pyrola incarnata Fisch. leaves were prepared and their antioxidant activities were investigated by using four antioxidant assays in vitro. The ethyl acetate fraction showed remarkably strong antioxidant activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ABTS radical scavenging, reducing power and β-carotene-linoleic acid bleaching, which were almost comparable to capacities of the positive controls (VC and BHT). The ethyl acetate fraction had the highest total phenolic and total flavonoid contents. Furthermore, Pearson correlation analysis was …

Alkyl- and aryl-substituted corroles. 4. Solvent effects on the electrochemical and spectral properties of cobalt corroles.

2003

Solvent effects on the electrochemistry and spectroscopic properties of alkyl- and aryl-substituted corroles in nonaqueous media are reported. The oxidation and reduction of six compounds containing zero to seven phenyl or substituted phenyl groups on the macrocycle were studied in four different nonaqueous solvents (CH(2)Cl(2), PhCN, THF, and pyridine) containing 0.1 M tetra-n-butylammonium perchlorate. Dimers were formed upon oxidation of all corroles in CH(2)Cl(2), but this was not the case in the other three solvents, where either monomers or dimers were formed upon oxidation depending upon the solvent Gutmann donor number and the number or location of aryl substituents on the macrocycl…