A total synthesis of (E)-11-hydroxyundec-2-enoic acid 10, an homologous of royal jelly acid and queen substance of honey bee was performed using commercially available nonan-1,9-diol. The general strategy including some key steps was based on the Wittig-Horner reaction of triethyl phosphonate in water in the presence of potassium carbonate on the protected 9-hydroxynonanal.
T. Turki, S. Khamri, H. Amri
Wittig-Horner reaction, (E)-11-Hydroxyundec-2-enoïc acid, royal jelly, honey bee
The chemical composition of the seed oil obtained from Onopordon nervosum subsp. platylepis Murb, endemic of Tunisia was determined. The seed oil was composed of eight acids; the predominant components were linoleic, oleic and palmitic. Nine triacylglycerols were identified; the major compounds are LLL, LLO and LLP with respectively 30.1%, 20.3% and 14.6%. The sterols constitute 0.13% of the oil, sitosterol and ∆-7 stigmastenol being the main constituents. The alpha tocopherol was identified with a concentration of 599 mg/kg of seed oil.
S.F. Hachicha, S. Barrek, T. Skanji, Z.G. Ghrabi, H. Zarrouk
Onopordon nervosum, fatty acids, triacylglycerols, sterols, alpha-tocopherol
The aim of this work is the elimination of one organic dye that is the metylene blue of raw chemical formula C16H18CIN3S, 2H2O by the adsorption technique. The used adsorbant is natural clay that is a bentonite. Its utilization requires a streamlined regime of the fluidization in order to overcome the problem of the plugging of the clay bed. In the first stage of this work two types of isotherm models were tested to determine the adsorption capacity of our clay vis-à-vis the methylene blue; that is those of Langmuir and Freundlich. We find that the model of Langmuir describes the adsorption and gives an adsorption ultimate capacity of the order of 238 mg/g. In the second stage, we built up a pilot installation so as to use it in an industrial scale. The third part is about the identification of the streamlined regime of working of the adsorption column. We localized the streamlined regime of the column adsorption, therefore the mass of clay and the speed of the solution in order to assure a good fluidization. This streamlined survey is followed by the residence time distribution survey (RTD). For it, the method of injection by impulse of a salt that is the KCl to a concentration of 1 mol/l is used. To follow the historic of this tracer, a conductimeter method is used. This part permits to identify the model of out-flow that is piston with an axial dispersing. In a last step, a modelisation of adsorption in a fluidized bed is made. This system is based on matter balance in the column of adsorption and on the equation of the model of adsorption isotherm. This one is transformed into a differential system by doing a spatial discretisation and using a Runge Kutta method.
N. Hamouda, I. Zouari, A. Gannouni, A. Bellagi
adsorption, clay, fluidised bed, hydrodynamic
Silica gels used were obtained by alkaline attack of Tunisian sand, coming from Feriana region. A kinetic of methylene blue adsorption in liquid phase onto silica gels has been studied. The results show the effects of silica gel pH, initial concentration of methylene blue and temperature on adsorption capacity. Adsorption isotherms have been determined and fitted according to the Langmuir and Guggenheim N Anderson NDe Boer (G.A.B.) equations. A high adsorptive capacity was observed. Thermodynamic parameters such as ∆H and ∆S were determined.
M. Besbes, N. Fakhfakh, M. Benzina
silica gel, adsorption, isotherms, kinetics, modelling
The Catalytic Wet Air Oxidation (CWAO) of aqueous solutions of p-hydroxybenzoic acid (a phenolic compound typically found in olive mill wastewaters) has been carried out over titania supported ruthenium catalysts (Ru/TiO2) at 140°C and 50 bar air. The ruthenium catalysts were prepared by the sol-gel method, either from solutions containing the Ru and Ti precursors, or by impregnation with ethanolic solutions of ruthenium acetylacetonate of TiO2 prepared by sol-gel). Ru catalysts were able to remove most of the Total Organic Carbon (TOC) of aqueous solutions of p-hydroxybenzoic acid. The most important intermediates detected were phenol, hydroquinone and maleic acid. The influence of catalyst preparation, of drying of the gel and of pre-calcination of the catalyst precursor at 300°C under oxygen before reduction on the performances for conversion of p-hydroxybenzoic acid have been studied.
M. Triki, D. Pham Minh, Z. Ksibi, A. Ghorbel, P. Gallezot, M. Besson
Wet air oxidation, Olive mill wastewaters, Sol-gel, Titanium oxide, Ruthenium catalysts
The title compound, [NC5H12+]•[H2PO4], was synthesized hydrothermally at 453 K. Its structure, determined by single crystal X-ray diffraction. is trigonal with the space group R3̅ (N°148) and the following unit cell parameters : a = 23.218(4) Å. c = 58.40(3) Å, V = 27266.9(1) Å3 and Z = 18. The refinement of the data leads to a factor R of 0.056 and an Rw of 0.25 for 5159 reflections with l>4σ(l). The atomic arrangement presents extended corrugated chains strongly linked together by (O-H...O) hydrogen bonds, to delimit tunnels developing along the  direction. Organic cations, located inside the tunnels, are maintained to phosphate groups via weak (N-H...O) hydrogen bonds. X-ray powder diffraction, IR and NMR spectroscopic studies support basically the structure refinement.
A. Dakhlaoui, L. S. Smiri
Hydrothermal Synthesis, X-ray diffraction, Infrared and NMR Spectroscopies, Thermogravimetric Analysis (TGA), Crystal Structure
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