JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Synthesis of substituted bis(allyl) polythioethers: Application for the synthesis of crown thioethers

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Present study describes the synthesis of a novel substituted bis (allyl) thioethers by the condensation of thioetherdithiols with different allylchlorides. Representative example of the cyclization of the diallylpolythioethers via intramolecular radical reaction is presented. The corresponding crown thioetheris is obtained in good yield and high purity.

I. Gara Dallali, H.M. Sbihi, M.M. Chaabouni, M. Romdhani-Younes

Polythioethers, crown thioethers, allyl thioethers

Pages 77-82

Microwave irradiation synthesis of 3-(2-hydroxyalkyl)-2-methylquinazolin-4(3H)-ones and their functionalization using the Mitsunobu reaction

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The synthesis of quinazolinones using a microwave method and their functionalization with the Mitsunobu reaction were investigated. The microwave method was proven to be rapid, simple and efficient in the synthesis of the starting quinazolinone. The results show an increase of obtained yields when compared with the conventional thermal method and the formation of the final derivatives in one step reaction without the activation of the alcohol function. The title quinazolinones were functionalized with a variety of variously substituted phenols using the Mitsunobu reaction to produce the corresponding new ether bridged derivatives in a 57-87% yield.

T. Saïed, N. Jelaiel, M.L. Efrit, C. Comoy, Y. Fort

Quinazolinone, Mitsunobu reaction, Microwave synthesis

Pages 83-88

Design and Synthesis of new antimicrobial [1,2,4]triazolo[1,5-c]pyrimidines

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The synthesis of 14-(aryl)-14H-naphtho[2,1-b]pyrano[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine-2- acetonitriles 4a-e has been accomplished using three steps of reaction using the 2-amino-naphthopyrane-3-carbonitriles 1a-e as useful key intermediates. Compounds 4a-e are used as precursors for the preparation of new triazolopyrimidine derivatives 5, 6, 7 and 8. Structures of these compounds were established on the basis of 1H NMR, 13C NMR and HRMS. The synthesized compounds were also screened for their antimicrobial activity.

A. Ben Said, A. Rahmouni, M. Daami-Ramadi, A. Romdhane, H. Ben Jannet

Naphtopyrane, Triazolo[1,5-c]pyrimidine acetonitrile, Antibacterial activity, Antifungal activity

Pages 94-104

Methane combustion over Pd/Al-MCM-41catalysts: The effect of palladium precursors and the preparation route

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The effect of palladium precursors and the preparation route on the catalytic performance of mesoporous materials Pd/Al-MCM-41 in methane oxidation was investigated in this work. The catalysts were prepared using both methods, namely hydrothermal method (DHT) and template ion exchange method (TIE), from three different palladium precursors Pd(NH3)4Cl2, PdCl2(MeCN)2 and Pd(acac)2. All catalysts were characterized by a variety of physico-chemical techniques such as X-ray diffraction (XRD), N2 physisorption, H2 chemisorption, temperature programmed desorption of H2 , diffuse reflectance UV–visible spectroscopy andelemental analysis by ICP, and then tested in methane combustion. According to the obtained results, the use of different palladium precursors and preparation routes play an important role on the catalytic properties of materials. The use of bis(acetonitrile)palladium (II) chloride as precursor by the TIE method seems to conduct to the best catalytic performance. This is in agreement with a better dispersion of PdO nanoparticles, thus optimizing the accessibility of reactants to the active sites in the mesoporous channels of Al-MCM-41.

A. Gannouni, S. Zribi, R. Dardouri, M. Saïd Zina

Al-MCM-41, Palladium, Template ion exchange, Hydrothermal, Methane

Pages 115-123

Antioxidant and antiglycated activities of polysaccharides from Tunisian date seeds (Phoenix dactilyfera L.)

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The extraction and purification of polysaccharides from date seeds (Phoenix dactilyfera L.), as well as the evaluation of their antioxidant and antiglycated activities in vitro were investigated. Aqueous and oxalate extracts (PPW and PPO) were obtained by sequential extraction from date seeds powder. Sugar contents and macromolecular characteristics were estimated by colorimetric assays and size exclusion chromatography (SEC/MALS/VD/DRI). The best yield was obtained for aqueous extract PPW (1.9%). These experiments showed that all extracted samples were polysaccharides having a moderately high molecular weight (1680 and 1200 kDa for PPW and PPO, respectively). Preliminary antioxidant and antiglycated tests indicated that PPW showed even better ability in the scavenging of DPPH• and NO• radicals and the inhibition of lipid peroxidation and protein glycation. These findings suggest that water-soluble polysaccharides from date seeds could be explored as free radical scavengers and protein glycation inhibitors.

W. Marzouk, M.A. Chaouch, J. Hafsa, D. LeCerf, H. Majdoub

Phoenix dactilyfera L., date seeds, polysaccharide, antioxidant activitiy, antiglycated activity

Pages 124-130

Biosorption of azo dye onto date seeds: Thermodynamic, kinetics and equilibrium studies

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The aim of this paper is to study the date seeds potential for azo dye biosorption of from aqueous solution. As shown in SEM analysis, treated date seeds were found to be effective in methyl orange dye removal. Thermodynamic parameters depicted the exothermic nature of biosorption and the process was feasible and spontaneous at all temperatures (293-313 K). Kinetic results showed that the pseudo-second-order kinetic model was well fitted to the experimental data and indicated that the biosorption was classified as chemical process. The Langmuir and Dubinin–Radushkevich (D–R) isotherm models were applied to the equilibrium data. Adsorption data were well described by the Langmuir and the maximum uptake of methyl orange onto date seeds was found to be 47.61 mg g-1 . The mean free energy for azo dye from the D-R isotherms confirms that the methyl orange was chemisorbed onto treated date seeds.

A. Rezgui, E. Guibal, T. Boubaker

Date seeds, biosorption, SEM analysis, isotherms, kinetic, chemisorption

Pages 131-136

Laurus nobilis green inhibitor for patinated bronze protection in sulfate media

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The inhibiting effect of Laurus nobilis extract on the corrosion behaviour of patinated bronze was evaluated by means of potentiodynamic polarization, statistical experimental design, Raman spectroscopy and quantum chemical calculations. The patina layer was electrodeposited at the Cu10Sn bronze alloy in aqueous chloride electrolyte under anodic conditions. Electrochemical and Raman characterizations showed the presence of various tin oxides and crystallized as well as porous cuprite in the chloride patina layer. The statistical experimental design was investigated to model the Laurus nobilis inhibition of the patinated bronze in sulfate electrolyte. The plant extract was found to act as mixed type inhibitor. The relatively low protection efficiency was related to the synergetic effect between the experimental parameters. Quantum chemical calculations were performed with the DFT method at the B3LYP/3-21G basis set. The results revealed that the major molecule inhibitor could interact preferentially with tin oxide.

A. Chaabani, S. Aouadi, M. Ben Messaouda, A. Moadhen, A. Madani, N. Bellakhal, N. Souissi

Cu10Sn alloy, patinated bronze, green inhibitor, experimental design, DFT

Pages 137-146

A preliminary study of phosphogypsum transformation into calcium fluoride

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Phosphogypsum is a waste by-product of the phosphate fertilizer industry, which is usually disposed in the environment because of its restricted use in industrial applications. The aim of this study is to reduce this environmental risk by producing calcium fluoride and sodium sulphate from phosphogypsum and sodium fluoride. To optimize this reaction, many factors have been considered such as temperature, reaction time, NaF/phosphogypsum molar ratio, stirring speed, reagents adding mode and phosphogypsum mass. The obtained results have shown that the NaF/phosphogypsum molar ratio, the reaction time and the phosphogypsum mass were the most influential parameters. Optimal conversion conditions were obtained with the NaF/phosphogypsum ratio between 1.5 and 2, at an average reaction time between 30 minutes and 120 minutes and at room temperature. In these conditions, the results are very satisfactory, in terms of quantity and quality of the obtained CaF2 and Na2SO4 , the conversion rate has exceeded 95%.

H. Douahem, H. Hammi, A.H. Hamzaoui, A. M’Nif

phosphogypsum, calcium fluoride, conversion, conditions

Pages 147-151

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