Bis-(β-cyanohydrins) polyoxyethylene glycols, obtained by opening reaction of diglycidyl ethers in the presence of potassium cyanide, was converted to dinitrile α,β-unsaturated via two methods. The first was carried out in the presence of tosyl chloride in a basic medium while the second was conducted by the action of thionyl chloride in a mixture of toluene-pyridine at 80°C. Each synthetic method gives a mixture of two isomers ZZ and EE whereas the ZE-isomers are not observed. The mechanism of reaction follows a bimolecular elimination E2.
S. Ghrab, L. Aroua, M. Beji
β-cyanhydrin, α,β-unsaturated nitrile, Oligoethylene glycols diglycidyl ethers, potassium cyanide
Application of thiol-ene chemistry on chloro-allyloxy-tetrazine shows an incompatibility of the s-tetrazine ring with radical addition. Thus, in order to synthesize new dialkoxy-s-tetrazines including a fluorinated substituent, thiol was added across allylalcohol and the resulting intermediate was then allowed to react with dichloro-s-tetrazine. Subsequent substitution on the second chlorine leads to disubstituted derivatives.
R. Guermazi, G. Clavier, A. Hedhli, P. Audebert
Radical addition, fluorine, tetrazine, thiol
In this paper, we report the synthesis and spectroscopic characterization of some representative N-alkylsubstituted quaternary ammonium salts derived from quinine using carbazole derivatives as alkylating agents.
S. Eltaief, B. Ben Hassine
Quaternary ammonium salts, carbazole derivatives, quinine
The anionic calixarene derivatives ('calixanions') have been obtained by the reaction of weak bases such as triethylamine, with p-tert-butylcalix[n]arenes in MeCN. To clarify the involvement of the solvent in deprotonation, comparison of media effect (MeCN and DMF) and computational methods (Frontier Molecular Orbital Theory) are employed. The binding of representative lanthanide(III) cations with p-tert-butylcalix[n]arenes (n=4, 6, 8) anions form in MeCN monomeric complexes in the case of tetra and hexa calixarenes, and dimeric complexes with the larger calixarene ,calixarene. The conditional stability constants of the lanthanum (La3+), europium (Eu3+), gadolinium (Gd3+) and terbium (Tb3+) complexes were determined. In addition, it was found that deprotonated p-tert-butylcalix[n] arenes (n=4, 8) present an affinity toward europium, while p-tert-butylcalixarene anion shows a significant selectivity for lanthane cation.
I. Hamzi, K. Essalah, R. Abidi
Calixanions, Lanthanides (III), Complexation, Absorption spectrophotometry, Frontier Molecular Orbital Theory (FMO)
Nanocrystalline zinc sulfide (ZnS) was synthesized by simple chemical precipitation in aqueous medium at 80°C using zinc nitrate and thioacetamide (TAA) as reactants. The prepared products were annealed in air at different temperatures in the range of 500–650°C. The as-prepared and annealed samples were characterized by different techniques. The structure and morphology of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra-red (FT-IR) and Energy-Dispersive X-ray (EDX) spectroscopies. From the XRD and FT-IR analysis, the crystal structure is found to convert from cubic ZnS phase to the hexagonal ZnO phase with the increasing annealing temperatures. The electrical properties of ZnO nanopowder were investigated using impedance spectroscopy. The electrical conductivity increases with increasing temperature with a typical Arrhenius-type behaviour. The Arrhenius plot presented two linear portions indicating tow dominant mechanisms affecting the electrical conductivity of ZnO.
A. Yacoubi, T. Ben Chaabane
Zinc sulphide, Zinc oxide, Annealing effect, Nanoparticles, Nanotechnology, Impedance spectroscopy, Electrical conductivity, Activation energy
Pure phase BiFeO3 (BFO) nanopowders were successfully fabricated by a low-temperature hydrothermal synthesis. Effects of the initial KOH concentration and reaction time on the evolution phase of BFO were systematically investigated. The pure BFO was obtained at the temperature of 200°C by using the KOH concentration of 8M during 6 hours X-ray powders diffraction (XRD) data refined via Rietveld method indicate that BFO crystallites are in single phase and show a rhombohedra perovskite structure with R3c space group. Differential thermal analysis (DTA) was used to determine the ferroelectric Curie temperature TC at ~817.49°C. FTIR spectroscopy analysis supports the formation of perovskite structure of BFO.
A. Marzouki, H. Harzali, F. Saida, A. Megriche, K. Zehani, L. Bessais
Multiferroic, bismuth ferrite, hydrothermal synthesis, ferroelectric
The quality of Portland cement clinker depends upon the quality of the raw materials (limestone, marl,
clay… ) especially marls and clays. These materials are the proponents of the cement quality and the main controllers
of the production cost. Bizerte Cement factory has carried out a complete study of the raw materials in which a variety
of clays and marls have been selected from its quarries and prepared for different analyses (chemical analysis, atomic
absorption, diffraction X, fluorescence X) in order to expand the range of existing materials and improve the quarries
management.The results are used to calibrate an ARL 9900 spectrometer installed in the laboratory.
S. Boughanmi, I. labidi, H. Tiss, A. Megriche
Portland cement clinker, raw materials, Clay, Marls, calibration program, X-ray diffraction, X-ray
fluorescence, calibrate, ARL 9900
The performance of a nickel-metal hydride (Ni-MH) battery mainly depends on the characteristics of the negative electrode. The electrochemical characteristics of mechanically alloyed compound LaCaMgNi9 , including the discharge capacity and the hydrogen diffusion coefficient, were studied as function of mechanical alloying (MA) conditions. The electrochemical measurements show that the LaCaMgNi9 electrode has a maximum discharge capacity of 150 mAh/g at a discharge rate of C/3. The hydrogen discharge capacity decreases dramatically when the MA exceeds 20h.
S. Chebab, M. Abdellaoui, M. Latroche, V. Paul-Boncour
AB3-type alloy, mechanical alloying, electrochemical characteristics
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