Ethanol 95 % was tested to esterify oleic acid and free fatty acids of olive oil. Esterification reaction, catalysed by sulfonic ion exchange resin (SPC 118), was studied at hight temperature. In an continuous reactor, it showed that ethanol 95% can be used under the same conditions and yields than anhydrous ethanol or methanol.
M.H. Frikha, M. Benzina
α-Functional methyl vinyl ketone 2 reacts with magnesium dialkyl cuprates generated in situ to produce the corresponding γ-ketoesters 3 in good yields.
T. Ben Ayed, M.M. El Gaied, H. Amri
The 1,3-dipolar cycloaddition of 2-diazopropane 1 with enones 2 carried out at -60°C has enabled us to observe, for the first time, the formation of an unexpected derivative of the oxadiazoline 6; normally this compound is difficult to prepare. The synthesis of Δ3-(l ,3,4)-oxadiazoline 6 was obtained via the intermediate of Δ1-pyrazoline 3 which is unstable, but in this case it was stabilised by the formation of the oxadiazoline 6 itself. Nevertheless, at 0°C, the intermediate of Δ1-pyrazoline 3 always rearranged by proton migration to give exclusively the more stable Δ2-pyrazoline 4.
R. Gharbi, Z. Mighri, A. Khemiss
Fe(NO)2(PPh3)2 and Fe(NO)2I(PPh3)2 Complexes, in solution, and supported by fonctionalized polymers have been used as catalysts in the oxidation of cyclohexene by molecular oxygen (O2). Moreover, it has been found that this oxidation involves the group nitro-nitrosyle coordinated to iron. In contrast, the complex: Fe(NO)2(PPh3)2 does not present any reactivity towards the oxidation reaction of cyclohexene, indeed the oxidation causes an alteration of the ligand (when the complex in solution is used) or a loss of the metal on the support. Furthermore, the selectivity induced by the complex supported Fe(NO)2I(PPh3)2, is different from the one induced by homologous complex in solution. As a matter of fact, the complex in solution provides the epoxide in 22% yield, whereas the supported one leads to the formation of three compounds: epoxide 22 % cyclohexenol 40 % and cyclohexenone 33%.
We have used Juncus fontanesii to eliminate the lead and copper from pure aqueous solutions containing these metals at 50, 100, 150 and 300mg/l. The densities of the fresh biomass were 2.8 and 5.6 kg/m2. This study, without adding nutritive elements, shows that we can eliminate more than 99% of lead within 3 to 12 days and copper within 12 to 21 days. 50 to 80 % of the metal are fixed by the roots, the remaining is located at the leafs and stems. When the concentration is higher than 100 mg/I, plant releases part of the copper to the medium. During the experiment the plants did not display any visual sign of perturbation.
M.A. Oueslati, M. Haddad
lead, copper, heavy metals, Juncus fontanesii, aquatic plants
A synthesis route of MFI type zeolites consist a in replacing the usually mineralizer OH- anions by F- anions. This allows crystallization in wide range of pH (alkaline and non alkaline media). In alkaline fluoride media at pH 10-12, the synthesis was carried out under mild operating conditions (T=90-100°C) during 5 days. In view of this, we have performed a series of experiments in order to obtain the optimal composition of gel mixture, which leads to pure phase, without any undesired impurity. The as- synthesized samples were characterized with various techniques (XRD, IR, MEB).
Z. Lounis, F. Djafri, A. Djafri
The orientation of three iodobenzenes (C6H5I, o.C6H4I2, p.C6H4I2) in three nematic liquid crystals with different aromaticities has been determined by measuring the proton-proton and the proton-carbon 13 dipolar couplings. Assuming a solvent-solute interaction potential based entirely on dispersion forces, it was found that the less aromatic the solvent the better the agreement between theory and experience. The discrepancies are probably due to the formation of charge-transfer molecular complexes.
Y. Arfaoui, E. Haloui
NMR, nematic liquid crystal, iodobenzenes, dispersion
Starting from sclareol 2 , Anthrax® 5 has been constructed by two separate, three steps pathways, via sclareolide 1, or via sclareol oxide 3. In the first synthesis the key reactions are formation of sclareolide 1 from sclareol by oxidative degradation with O3/peroxides/NaOH, and its reduction to the diol 4 with LiAlH4. The second sequence involves the synthesis of sclareol oxide 3 , which is concerted by reaction with ozone and in situ reduction with NaBH4 to the diol 4. Cyclisation of diol 4 obtained by either method, then yields Ambrox 5.
A. Fekih, A. Khemiss
Ambrox, sclaréol, sclaréolide, sclaréol oxyde
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