JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Synthesis of bis-(oxabicyclic tetrazole) polyoxyethylene via an intramolecular [2+3] cycloaddition of bis-(azidonitrile) polyoxyethylene derivatives

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Oligoethylene glycol diglycidyl ethers 1 were converted by the action of sodium azide in the hydro-methanolic medium into the corresponding (azido alcohols) 2. The latter react with 2-chloroacetonitrile in the presence of potassium t-butoxide in one pot, leading to new condensed ring systems 1,5-tetrazole 4 via an intramolecular [2+3] cycloaddition reaction. The present method avoids the formation and isolation of azido nitrile 3 generated in situ and also the use of any catalyst.

L. Aroua, A. Baklouti

oligoethylene glycol diglycidyl ether, tetrazole, sodium azide, chloroacetonitrile, potassium t-butoxide, intramolecular [2+3] cycloaddition reaction

Pages 75-82

Hydrodistillation kinetic and biological investigations of essential oils from the Tunisian Crithmum maritimum L.

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This work describes the study of the chemical composition and bioactivity of the essential oils of Crithmum maritimum and the location of dillapiole one of their major and bioactive constituents. This compound was detected at increasing percentages in all the collected fractions during the extraction process. The highest percentage of dillapiole was obtained in the last fraction (F9) with 100% in the roots. The essentials oils of roots and aerial parts and F9 were assayed for their antiradical and enzymatic antioxidant properties (Catalase and Paraoxonase), the results showed that F9 and the roots essential oil improve the activity of Catalase and Paraoxonase, respectively. The isolated oils and F9 were tested against five bacteria and four candida species. The oil roots exhibited significant activity towards Staphylococcus aureus and Enterococcus faecalis. Dillapiole was found to be the strongest anticandidal. The cytotoxic activity of essential oils and F9 was evaluated against Hela and A549 cancer cell lines. F9 exhibited the best cytotoxic effect against Hela cell line. These results may suggest that C. maritimum essential oils can be used as a good source of dillapiole which could be used as a natural preservative ingredient in food and/or for pharmaceutical preparations.

A. Nguir, M. Znati, M. Garrab, G. Flamini, M.A. Hamza, H. Ben Jannet

Essential oil, Crithmum maritimum L., Dillapiole, Antioxidant activity, Antimicrobial activity, Cytotoxic activity

Pages 83-94

Isothermes de sorption et propriétés thermodynamique de l’Allium sativum

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The objective of this work was to determine the desorption isotherms and thermodynamic properties of Allium sativum. These properties are indispensable, particularly in regard to garlic drying and storage in order to guarantee its quality prior to its industrial use as an important source of nutriment and meal for medicinal and cosmetic purposes. Desorption isotherms were determined using a static gravimetric method at four temperatures: 40°C, 50°C, 60°C and 70°C over a relative humidity range of 5-90%. All the curves exhibited type II behavior, according to Brunauer’s classification. Equilibrium moisture contents decreased as the temperature increased. The GAB model fitted well the desorption isotherm data for Allium sativum with the monolayer moisture content depending on the temperature. The Clausius-Clapeyron equation was used to evaluate the net isosteric heat of water desorption by using the GAB theoretical model in the studied temperature range. The net isosteric heat and the differential entropy decreased strongly as the moisture content increased respectively.

A. Touil, J. Litaiem, F. Zagrouba

Garlic, Sorption isotherms, Modelization, Enthalpy, Entropy

Pages 105-114

Etude des propriétés mécaniques d’alliages à base de Ti3SiC2 élaborés par frittage flash

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Ti3SiC2-based materials were elaborated by spark plasma sintering from a powder mixture of Ti/SiC by varying the temperature from 1300°C to 1400°C during three different durations (10, 15 and 20 min). The phases’s lattice parameters of the obtained bulk materials as well as the lattice volumes, the weight contents and the crystallite sizes were determined by XRD patterns refinement based on the Rietveld method. The results showed that by optimizing the sintering conditions, a Ti3SiC2 based material with a weight content of about 62% can be obtained. The powder sample sintered at 1400°C during 20 minutes is a nearly a fully dense material (> 99%) and has advanced mechanical properties.

F. Turki, F. Schoenstein, M. Abdellaoui, N. Jouini, H. Abderrazak

Ti3SiC2 carbide, spark plasma sintering, relative density, mechanical properties

Pages 115-127

Synthesis and structural characterization of diammonium bis[octaaquastrontium] decavanadate dehydrate (NH4)2[Sr(OH2)8]2 .V10O28.2H2O

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The title compound, (NH4)2[Sr(H2O)8]2[V10O28].2H2O 1, has one [V10O28]6- anion, two [Sr(H2O)82+] cation, two NH4+ cation and two water molecules. The crystal structure of diammonium bis[octaaquastrontium] decavanadate dihydrate has been determined by single-crystal X-ray diffraction in the space group P-1. The centrosymmetric polyanion [V10O28]6- consists of five independent [VO6] octahedra sharing edges and has approximate D2h symmetry. The compound is a classical isomer of decavanadate clusters, in which two centrosymmetrically related cyclic {V5O14} units are linked by bridging oxygen atoms. NH4+ and Sr(H2O)82+ acting as charge-compensating cations and space-filling structural subunits, are connected to the [V10O28]6- clusters by a complex network of hydrogen interactions via water molecules.

I. Mestiri, I. Nagazi, A. Haddad

Decavanadate, crystal structure, cyclic voltammetry

Pages 128-134

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