JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Synthèse d’aminopyrazoles N-phosphonatés

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The synthesis of series of N-phosphorylated 5-aminopyrazole derivatives is described in this work. The reaction involves malononitrile, an orthoester and  a phosphonohydrazine. The reaction mechanism was discussed.

D. Jabli, K. Dridi, M.L. Efrit

phosphorohydrazidic acid diethyl ester, thiophosphorohydrazidic acid O, O-diphenyl ester, ylidenes, 5-aminopyrazole

Pages: 1-7

1,3-dipolar cycloaddition reactions of pyrazolo[1,5-a]pyrimidines with nitrile oxide

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An example of 1,3-dipolar cycloaddition reactions of arylnitrile oxide to pyrazolo[1,5-a]pyrimidines was described. The nitrile oxide reacts with the C3 –C4 double bond of pyrazolo[1,5-a]pyrimidine to give the corresponding pyrazolo[1,5-a]pyrimidine -isoxazolidines in moderate yields. The mechanism was discussed and the structure of all compounds was studied by IR and NMR Spectroscopy (1H, 13C, 19F). Compound 4e was characterized by HRMS.

K. Bokri, I. Jalloul, M.L. Efrit, A. Ben Akacha

3,5-diaminopyrazole, pyrazolo[1,5-a]pyrimidine, 1,3-dipolar cycloaddition and arylnitrile oxide

Pages: 9-15

Synthesis and characterization of fluorinated 1,3,4-oxadiazole-2-thiones

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Oxadiazoles have attracted a wide attention of chemists in search of the new therapeutic compounds. Fluorine atom is often introduced into organic molecules to improve such a therapeutic activity. In this context, a series of perfluoroalkylated 1,3,4-oxadiazole-2-thiones was prepared from the corresponding hydrazides. Characterization of these new compounds indicates a displacement of the tautomeric equilibria in favour of the thione form.

R. Ben Châabane, A. Hedhli

hydrazide, 1,3,4-oxadiazole-2-thione, fluorine.

Pages: 25-28

Michael addition of nitroalkanes to allyl nitrile derivative: Synthesis of 1,2,3-trifunctionalized cyclopentanes

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An efficient conjugate addition of carbon nucleophiles such as nitronate salts to ethyl 5-cyanocyclopent-1-enecarboxylate 3, produces a variety of 1,2,3-trifunctionalized cyclopentanes 4 in satisfactory yields.

F. Saâdi, A. Arfaoui, H. Amri

​​​​Cyclic Baylis-Hillman adducts, DABCO, allyl nitrile, Michael addition, nitroalkanes, 1,2,3-trifunctionalized cyclopentanes

Pages: 29-34

Kinetic study by UV spectrophotometry of isoprocarb degradation in aqueous medium

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Anthropogenic compounds used as pesticides often persist in the environment and can cause toxicity to humans and wildlife. Some of them are easily degraded, whereas others are degraded very slowly or only partially, leading to accumulation of toxic products. This review examines the physico-chemical factors that affect the degradation of pesticides and the mechanisms by which new pathways emerge in nature. The present work deals with the degradation mechanism of an insecticide, Isoprocarb or 2-isopropylphenyl-N-methylcarbamate in aqueous media. It may result in the inhibition of the vital enzyme acetyl-cholinesterase. The reaction kinetics has been investigated using UV Spectrophotometry. The determination of 2-isopropylphénol, as the main degradation product of Isoprocarb hydrolysis gives evidence for the significant reactivity of this insecticide in alkaline solution. The rate constants were determined following a first order kinetic model. The obtained positive activation entropy ΔS = +21.78 J mol-1 K-1 and the absence of basic general catalysis indicate an E1cB mechanism involving unimolecular collapse of the Isoprocarb via a methylisocyanate intermediate. This elimination process is confirmed by the position of the point corresponding to the Isoprocarb on the Brönsted and Hammett plots, determined for a serie of substituted N-methylcarbamate which the decomposition mechanism in aqueous media proceede via E1cB.

H. Bakhti, N. Ben Hamida

Isoprocarb, carbamate, kinetic, mechanism, spectrophotometric UV

Pages: 35-43

Preparation and electrochemical properties of PPy/LiCoO2 composites cathode materials for lithium battery

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Layered LiCoO2 was synthesized by sol-gel process, and a polypyrrole/ LiCoO2 composite was then prepared by polymerizing pyrrole monomer in Pickering emulsion stabilized by LiCoO2 particles. The bare sample and composite were subjected to analysis and characterization by the techniques of X-Ray Scattering (WAXS), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The electrochemical properties of the composite were investigated with galvanostatic charge-discharge test and, which shows that the polypyrrole (PPy) significantly decrease the charge-transfer resistance LiCoO2. The composite containing 25 wt% PPy exhibits a good electrochemical performance, its specific discharge capacity is 178 mAhg−1 at C/20 rate and voltage limits of 3-4.5 V, while the capacity of the bare sample is only 136 mAhg−1.

K. Ferchichi, S.E. Boughdiri, N. Amdouni, V. Pralong

PPy, Conducting Polymer, composite materials, lithium battery

Pages: 45-52

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