Inhibitory effect of Acacia hamulosa methanolic extract on the corrosion of mild steel in 1 M hydrochloric acid

The flora of Saudi Arabia comprises about 18 species of Acacia species including Acacia hamulosa Benth. The methanolic extract of the flowering tops of A. hamulosa was tested for its radical scavenging activity toward 2,2-diphenyl-1-pricylhydrazyl (DPPH) radical and the activity was compared with L-ascorbic acid, quercetin and Trolox as standards. The total phenolic content was determined using Folin-Ciocalteu method. In addition the methanolic extract has been evaluated as a corrosion inhibitor for steel in 1 M HCl solution by means of weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). Tafel polarization study revealed that extract of Acacia hamulosa acts as a cathodic type inhibitor. Inhibition was found to increase with increasing concentration of the extract of Acacia hamulosa. Values of inhibition efficiency calculated from weight loss, Tafel polarization curves, and EIS are in good agreement. The effect of temperature on the corrosion behaviour of mild steel in 1 M HCl with addition of extract was also studied and thermodynamic parameters were determined and discussed.               KEY WORDS: Acacia hamulosa, Extract, Polyphenols, Antioxidant corrosion, Electrochemical study Bull. Chem. Soc. Ethiop. 2018, 32(2), 323-335.DOI: https://dx.doi.org/10.4314/bcse.v32i2.1

Hydrogen effect modeling on Ziegler-Natta catalyst and final product properties in propylene polymerization

Hydrogen, as chain transfer agent, effects on kinetic of propylene polymerization; consequently variation of hydrogen concentration leads to change final product properties and also activates site of used catalyst. This phenomenon is one of the most important process variables is to adjust the final product properties and optimize the operating conditions. This work has attempted to present a mathematical model that cable to calculate the most important indices of end used product, such as melt flow index, number and weight average molecular weight and poly dispersity index. The model can predict profile polymerization rates determining important kinetic parameters such as the activation energy, lumped deactivation reaction initial reaction rate and deactivation constant. The mathematical model was implemented in Matlab/Simulink environment for slurry polymerization in laboratory scale. The modeling approach is based on polymer moment balance method in the slurry semi-batch reactor. In addition, in this work have provided a model that calculating fraction activated sites catalyst via hydrogen concentration. The model was validated by experimental data from lab scale, reactor. The experimental and model outputs were compared; consequently, the errors were within acceptable range.               KEY WORDS: Mathematical modeling, Propylene polymerization, Kinetics study, Hydrogen response, population balance Bull. Chem. Soc. Ethiop. 2018, 32(2), 371-386.DOI: https://dx.doi.org/10.4314/bcse.v32i2.1

Diethyl 2-[(morpholin-4-yl)(phenyl)methyl]malonate

In the title compound, C18H25NO5, the morpholine unit adopts an almost ideal chair conformation. The crystal structure is consolidated by C - (HO)-O-... intermolecular hydrogen-bond interactions, providing stabilization. The molecular conformation shows two possible pockets ready to coordinate two metal atoms

Synthesis and crystal structure of the bis-calcimycin anion-Ni2+ complex

The X-ray structure of [Ni(calcimycin)(2)] complex shows two essentially identical conformations of the two calcimycin ligands in the dimeric association, in this ionophore family. In the title complex, the nickel (II) cation has a distorted O4N2 octahedral coordination environment

Crystal structure of a new polymeric thallium-lasalocid complex: Lasalocide anion-thallium(I) containing aryl-Tl interactions

The title complex, [Tl(C34H53O8)]n, forms a pseudo individual monomer complex, in which the anionic oxygen of carboxylate group serves to neutralise the charge of Tl+, the other five O centres of the first lasalocid anionic ligand (Lasa 1) and in which this ligand is pentadentate O-ligand and bonded to a second Tl centre by using phenyl-metal coordination. A second lasalocid ligand (Lasa 2) is also pentadentate O-ligand and bridges the first Tl centre within the polymer. The monomeric unit is stabilized by strong intramolecular aryl-Tl type-metal half sandwich bonding interactions. ©ARKAT USA, Inc

Synthesis of N,N'-bis and N,N,N',N'-tetra-[3,5-disubstituted-1-pyrazolyl)methyl]para-phenylenediamines: New Candidate Ligands for Metal Complex Wires.

International audienceA series of tridentate ligands N,N-bis-[(di-substituted-1-pyrazolyl)methyl]arylamines 2–3a,b and benzylamine 4a,b, tetradentate N,N′-bis-[(di-substituted-1-pyrazolyl)methyl]para-phenylenediamines 7a,b and hexadentate N,N,N′,N′-tetra-[(di-substituted-1-pyrazolyl)methyl]para-phenylenediamines 8a,b has been prepared in good yield by condensation of arylamines, benzylamine or para-phenylenediamine with N-hydroxymethyl disubstituted pyrazoles 1a,b. The synthesis and characterisation of these various polydentate ligands are described