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
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
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
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
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
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
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
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
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