Basic or acid alcoolisis of C≡N group in N-(cyanomethyl) imidates leads to imidazols derivatives. The intermediate diimidate is not isolated.
B. Hajjem. M. Kammoun, B. Baccar
Pages 355-360
The reaction of N-(N-phenylcarbothioamido) imidates with hydrazines leads to the corresponding 3-amino-1,2,4 triazols with good yields.
M.L. Efrit, A. Zarguil, B. Baccar
Pages 361-366
The action of ethylchloroformate on iminoesters, derived from 2-aminobenzimidazole, leads to the formation of imidates N-(1-carbo-ethoxy-2-benzimidazoyl) 2 . Treatment of theses compounds by primary amines yields to [1,2-a]benzimidazo-1,3,5-triazin-4-one 3.
R. Abderrahim, B. Hajjem, B. Baccar
Pages 367-372
Type A, X and Y zeolites have been synthesized from sodic silicoaluminate gels. The influence of the composition of the gel, reaction temperature, alkalinity and aging time on the kinetics of formation and nature and quality of the product has been investigated. High yields of crystals, above 90%, have been obtained.
F. Hamidi, A. Bengueddach, Z. Derriche, F. Fajula, F. Di Renzo
Pages 373-383
The presence of promoter ions in the Ni2+ /zeolithe X system has a great influence on nickel reductibility and formed metallic phases. The addition of Eu3+ ions allowed, after reduction of Ni2+, to the formation of a highly dispersed metallic state of nickel (d ≤ 12 Å). A similar dispersion can be obtained by using Cr3+ but with particle size superior to 20 Å. A comparative study of the reactivity of Ni°-Eu-zeolithe X and Ni°-Cr-zeolithe X systems showed a particular behaviour of nickel particles with diameter equal to or less than 12 Å. The chemisorption and catalytic properties of these particles are attenuated due to the formation of "hydrogen species" strongly chemisorbed on the nickel surface. These species inhibit the contact between sites and molecules to adsorb.
S. Djemel, A. Ghorbel
Pages 385-397
The aim of this work is to make a detailed study of kinetics of the grain's drying of diammonium phosphate (DAP) disposed in a fixed bed in order to determine the mechanisms restricting the thermal decomposition process. The decomposition rate is measured by a microbalance in an TGA apparatus. The solid sample formed by a pile of spherical grains of DAP is hanging on the scale and subject to a constant flux of heat.
M. Baguenne, A. Bellagi
Pages 399-409
Silica gels were obtained by alkaline attack of Tunisian sand. The influence of several pysico-chemical parameters such as temperature, pH, molar ratio K2O/SiO2 size particles and reaction time able to act on the transformations sand-sol and sol-gel was studied. The aerogels obtained by hypercritical drying showed a 5000 m2/g specific area.
J. Bouaziz, B. Elleuch, R. El Gharbi
Pages 411-419