JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Synthesis of 2-substituted-1,4-dioxanes

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The synthesis of 2-substituted-1,4-dioxanes may be realized by ring opening of 3-(2-chloroethoxy)-1,2-epoxypropane by nuclephiles (F-. N3-, CH3OH, PhSH) then cyclo-dehydrochloration of the formed ω-chloroalcohol for the 2-functionalized one, and from the bromoalkoxylation of olefins with N-bromosuccinimide (NBS) and ethylene glycol, followed by the cyclization of the formed bromohydrins for the 2-alkylated others.

M. Romdhani, M.M. Chaabouni, A. Baklouti

Pages 661-669

Hydrofluoration of allylic aziridines

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The ring opening of 1-phenyl-1-allylaziridines by triethylamine hydrofluoride or Olah's reagent is regioselective and allows the synthesis of the corresponding α-fluorinated amines. The regioselectivity depends on the nature of the fluorinating reagent.

M. El Kateb, A. Hedhli, A. Baklouti

Pages 671-674

Reaction of amines and hydrazines on 1,1,1-N-acylaminodialcoxyalcanes

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1,1.1-N-acylaminodialcoxyalcanes 1 react with primary amines, 2-amino-benzimidazole, hydrazines, orthophenylenediamines and orthoaminophenol to give respectively N-acyl amidines 2, benzimidazolotriazines 3, 1,2,4-triazoles 4, benzimidazoles 5, and benzoxazoles 6, in good yields.

A. Harizi, B. Hajjem, H. Zantour, B. Baccar

Pages 683-691

Characterization of a new organic-cation cyclotetraphosphate: [NH3(CH2)4 NH3]2 P4O12. 9/2H20

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Chemical preparation, differential scanning calorimetric analysis, IR spectrometric investigation and crystal structure are given for a new organic condensed phosphate. The putrescinium cyclotetraphosphate hydrate [NH3(CH2)4NH3)2P4O12.9/2H2O is monoclinic C2/c with Z=8 and unit cell dimensions: a=38.87(2)Å, b=9.478(2)Å, c=13.97(2)Å, β=96.51(7)°. The structure was refined to a final Rw value of 0.031. The atomic arrangement is a typical layer organization built by alternating layers of anions and cations. The anion layers, including P4O12 rings and water molecules, are in planes centered on z=1/4 and 3/4, while the cation layers, made up by the three independent putrescinium dications [NH3(CH2)4NH3]2+, are in planes centered on z=0.0 and 1/2. All the N–H...O hydrogen bonds are established between adjacent layers while the O–H...O bonds operate within the anionic layer linking (i) two P4O12 groups to form clusters: [(P4O12)2(H2O)3]8-, (ii) clusters to form infinite ribbons: [(P4O12)2(H2O)7]n8n- and (iii) ribbons to form an infinite two-dimensional layer. The DSC study shows that the dehydration occurs in three steps. Such dehydration process may be related to the different environments of the water molecules in H-bond schemes. The reported IR investigation, indicates a satisfactory agreement between the predicted, on the basis of a group theoretical analysis, and the observed P4O12 stretching bands, especially in the 800-600 cm-1 characteristic region for C1 symmetry.

H. Thabet, M. Bdiri, A. Jouini, A. Durif

Pages 693-708

Electrochemical behavior of the plain-steel in loaded natural waters

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This study interests in the behaviour of the plain steel in the contact of the loaded natural waters (high mineralization) of the underground water of Complex Terminal (Tozeur-Kebili area). This system is complex because of the nature of the products which settle at the surface of the electrode and the importance of the diffusion process. This is why we use the rotating electrode disk. This assures on one hand a hydrodynamic conditions well defined and allows on the other hand the application of the quantitative theory of matter transport. The settled corrosion products on the interface intervenes like an obstacle generating a molecular diffusion of the oxygen in the formed porous layer, but also a partial blockage of the interface (under cathodic polarization). They also constitute an obstacle to the diffusion of the ions Fe2+ toward the solution in the anodic domain. At the corrosion potential, the process is under mixed control of activation-diffusion, in the domain of the rotation speeds of the studied electrode. 

L. Bousselmi, E. Triki

Pages 709-726

Effect of polylysine on the adsorption of phosphate and nitrate ions on mercury/solution interface

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Nitrate and Phosphate ions (H2PO4-,HPO42-) adsorption were studied at the mercury / solution interface, by the measurements of the interfacial tension depending on the electrode potential and the salt concentration. In the presence of polylysine, the anionic adsorption is independent from the concentration. The polylysine eliminate the oxyanion effect in high charge for H2PO4- and NO3-. Any oxyanions adsorption is noticed by the addition of NaCl 0.5 M.

H. Ghabi, M. Dhahbi

Pages 727-737

Adsorption isotherms of water vapor on a natural clay

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Adsorption isotherms of water vapor on natural clay were obtained gravimetrically by a flow technic at 30, 40, 50 and 60°C up to the saturation pressure. The equilibrium data were also correlated by some theoretical models. The modified BET model was the best. The magnitude of the heats and entropies for constant loadings is indicative of physical adsorption and shows that the state of adsorbed water tends to that of condensed vapor near the saturation.

L. Gannouni, M. Baguenne, A. Bellagi

Pages 739-748

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