N-chlorobenzamide as volumetric reagent

Summary N-Chlorobenzamide has been used as a volumetric reagent for the visual and potentiometrie determination of some common reducing agents, hydrazines, and thioureas.

---

Zusammenfassung N-Chlorbenzamid wurde als volumetrisches Reagens für die visuelle und potentiometrische Bestimmung von einigen gebräuchlichen Reduktionsmitteln sowie von Hydrazin- und Thioharnstoffderivaten benutzt.

     

Functionalization of alpha,beta-unsaturated esters and ketones: a facile and highly stereoselective one-pot approach to N-protected alpha,beta-dehydroamino acid derivatives

A new, facile, and highly stereoselective protocol toward alpha,beta-dehydroamino acid derivatives has been developed. The one-pot synthesis was very convenient to perform by using the aminohalogenation reaction of alpha,beta-unsaturated esters and ketones followed by treatment with specific bases. Only two [2.2.2] bicyclic organic bases were found to be effective for this transformation. Good yields (58-68%) and excellent Z-selectivity were obtained for 12 examples. [reaction: see text]     

An expedient regio and diastereoselective synthesis of novel spiropyrrolidinylindenoquinoxalines via 1,3-dipolar cycloaddition reaction

We described an efficient and multicomponent approach for the synthesis of novel polyheterocyclic spiropyrrolidinylindenoquinoxalines via 1,3 dipolar [3+2] cycloaddition reaction of 3-methyl-4-nitro-5-alkenylisoxazoles, ninhydrin, orthophenylenediamine and benzyl amine. Excellent to good yields were obtained. Various isoxazole derivatives were used as dipolarophiles against substituted benzylamine and o-phenylenediamine. Diastereoselectivity was found to be variable and found to be dependent on the substitutions and their position on the aromatic ring of the reactants. This catalyst free and green approach is column free and does not even require a work up procedure.     

Optimal Ordering Policy for a Multi-item,Single-supplier System with Constant Demand Rates

This paper develops optimal inventory-management rules for an n-item system supplied by a common vendor and with constant demand rates for the various items. The model allows planned stockouts, whose optimal values are determined on the basis of the total cost minimization.     

A highly effective catalyst system for the Pd-catalyzed amination of vinyl bromides and chlorides

[reaction: see text] A highly efficient synthesis of enamines and imines by Pd-catalyzed amination of vinyl bromides or chlorides with amines is described using the Pd2(dba)3/P(i-BuNCH2CH2)3N catalyst system.     

P[N(i-Bu)CH2CH2]3N: a versatile ligand for the Pd-catalyzed amination of aryl chlorides

[reaction: see text] Palladium-catalyzed amination reactions of aryl chlorides with amines proceeded in the presence of the bicyclic triaminophosphine P[N(i-Bu)CH(2)CH(2)](3)N to afford the corresponding arylamines in good to excellent yields. Electron-poor, electron-neutral, and electron-rich aryl chlorides all participated with equal ease.     

Bound Energy for the Exponential-Cosine-Screened Coulomb Potential

An alternative approximation scheme has been used in solving the Schrödinger equation for the exponential-cosine-screened Coulomb potential. The bound state energ?es for various eigenstates and the corresponding wave functions are obtained analytically up to the second perturbation term.     

Highly active palladium catalysts supported by bulky proazaphosphatrane ligands for Stille cross-coupling: coupling of aryl and vinyl chlorides, room temperature coupling of aryl bromides, coupling of aryl triflates, and synthesis of sterically hindered biaryls

A family of proazaphosphatrane ligands [P(RNCH2CH2)2N(R'NCH2CH2): R = R' = i-Bu, 1; R = Bz, R' = i-Bu, 3; R = R' = Bz, 4] for palladium-catalyzed Stille reactions of aryl chlorides is described. Catalysts derived from ligands 1 and 4 efficiently catalyze the coupling of electronically diverse aryl chlorides with an array of organotin reagents. The catalyst system based on the ligand 3 is active for the synthesis of sterically hindered biaryls (di-, tri-, and tetra-ortho substituted). The use of ligand 4 allows room-temperature coupling of aryl bromides and it also permits aryl triflates and vinyl chlorides to participate in Stille coupling.     

Synthesis and Characterization of Mn-Doped ZnO Nanocrystals

We report the synthesis and characterization of several sizes of Mn-doped ZnO nanocrystals, both in the free-standing and the capped particle forms. The sizes of these nanocrystals could be controlled by capping them with polyvinylpyrollidone under different synthesis conditions and were estimated by X-ray diffraction and transmission electron microscopy. The absorption properties of PVP-capped Mn-doped ZnO exhibit an interesting variation of the band gap with the concentration of Mn. Fluorescence emission, electron paramagnetic resonance, and X-ray absorption spectroscopy provide evidence for the presence of Mn in the interior as well as on the surface of the nanocrystals.     

Spontaneous self-assembly of cerium oxide nanoparticles to nanorods through supraaggregate formation

Self-assembly of cerium oxide nanoparticles to nanorods is reported. Such nanorods have an aspect ratio of 6 with a diameter of approximately 40 nm. The formation of cylindrical supraaggregates and their subsequent growth by preferential assembling of ceria nanocrystallites along the longitudinal direction was proposed to be the probable mechanism of spontaneous self-assembly of nanorods. The supraaggregate formation was facilitated by influencing the local curvature of the micelle surface in the presence of nitrate ions as a precursor solution. The nanorods were characterized using high-resolution transmission electron microscopy with energy dispersive spectroscopy and selected area electron diffraction for their morphology, chemistry, and crystal structure.