JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Reactivity of insaturated 2-fluoroalkyl p-toluene sulphonates with some nucleophiles

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The insaturated fluorotosylates were converted to saturated fluaroalkyl hydrazines by action of hydrazine. The action of potassium thiocyanate and sodium cyanide on these fluorotosylates allows respectively the preparation of homologous fluoroalkyl thiocyanates and insaturated alkanedinitriles.

B. Charrada, A. Hedhli, A. Baklouti

fluorotosylates, fluoroalkylhydrazines, dinitriIes

Pages 79-84

γ-ketophosphonates: Synthesis and 1H, 31P and 13C NMR study

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γ-ketophosphonates 1a and 1b have been prepared. We have confirmed that the mechanism of the reaction leading to ketones 1b involves the formation of an oxaphosphorane intermediate. The application of two dimentional homonuclear 1H NMR to compounds 1a indicate a 5JHH coupling interaction, probably via a non-bond mechanism. A conformational approach for ketones 1a and 1b has been proposed on the basis of 3JCP coupling constants.

S. Touil, E. Kremp, B. Baccar, H. Zantour

Pages 85-95

Microwave activated acetylation of secondary alcohols without solvent and solid support

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Acetylation of various alcohols was realised with microwave activation in the absence of solvent and solid support. Tertiary alcohols did not yield the expected esters but the acetylation of secondary alcohols was accomplished with excellent yields.

N. Kammoun, Y. Le Bigot

Esterification, secondary alcohol, acetic anhydride, microwave

Pages 97-100

Electrochemical reduction of pulegone

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The electrochemical reduction of pulegone has been studied in different solvents. It appears from voltametric and coulometric studies that dimerization is the main reduction way. Water facilitates the reduction in dimethylsulfoxide and acetonitrile and increases dimerization oppositely to the bielectronic reduction which leads to menthone. The last product appears often as a secondary product in exhaustive electrolysis. Three types of dimers are also formed in variable amounts: the ε-diketone and two products resulting from dehydration of hydrodimers.

F. Matoussi Mhalla, S. Harrazi

pulegone , menthone , electron exchange, electrohydrodimerisation

Pages 101-110

Inhibition of the geothermal water’s scale in the south of Tunisia, effect of temperature

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Characteristics of geothermal waters from the South of Tunisia are described. Their high hardness has disastrous consequences. Chronoelectro-gravimetry allows an evaluation of their scaling tendancy. It is shown that sodium tripolyphosphate at very low concentration (0.8 mg.l-1 that is 2.2 µmol.-1) inhibits totally calcium carbonate precipitation at 60°C.

K. Walha, M. Ben Amor, R. Rosset

scaling tendency determination, chronoelectrogravimetry, antiscale inhibitors, sodium phosphate

Pages 111-128

Study of highly siliceous MFI zeolites prepared in fluorine medium by solid state 29Si, 27Al and 19F NMR

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Highly siliceous MFI-type zeolites, containing tetrapropylammonium and synthesized in the presence of fluoride ions, were characterized by high resolution solid state 29Si, 27Al and 19F NMR was revealed the presence of some extra-framework species and of quantify of structural defects. Various post-synthesis treatments, namely calcination at 550°C under air of these zeolites led to partial or nearly total healing of these defects in the final materials.

Z. Lounis, F. Djafri, H. Taibi, A. Bengueddach, A. Djafri

Zeolites, alumino-silicate, ZSM-5, RMN 29Si,27Al and 19F

Pages 129-135

Effect of surface state of Ni-Ce-zeolites X, Ni-Eu-zeolites X and Ni-Cr-zeolites X systems on the reduction of nickel

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Surface properties of Ni2+ zeolites X are strongly modified in presence of ion Ce3+, Eu3+ and Cr3+. In fact, the different states of valence of these ions (initial state and that acquired during reduction of Ni2+) have a great effect on zeolite redox properties. They influence the reduction of Ni2+ by displacing the redox equilibrium Ni2+ / Ni° and the electronic interaction between the support and nickel metallic particles formed causing their stabilization in a highly dispersed state into the zeolith-framework.

S. Djemel, A. Ghorbel

Pages 137-148

Cristalline structure of 2-[4-phenyl-5,5-dimethyl-4,5-dihydro-3H-pyrazol-3-YL]-5,5-dimethyl-2-(naphtalene-2-YL)-2,5-dihydro-(1,3,4)oxadiazole, C25H26N4O

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C25H26N4O, Mr = 398.50 g.mol-1, crystallizes in the orthorhombic system, space group P212121. The cell parameters are: a = 8.301(2) Å ; b = 11.539(2) Å ; c = 22.976(4) Å, V = 2200.8(8) Å3, with Z = 4. The molecular groups are organized in corrugated layers perpendicular to the c direction. The intramolecular linkage into and between thoose layers, is performed by Van Der Waals interactions N...H and O...H. The crystallographic study of the title compound has enabled us to confirm the unexpected molecular structure deduced from NMR study.

R. Gharbi, A. Haddad, Z. Mighri, A. Khemis

Pages 149-156

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