JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Synthèse Sol-Gel: Application à la silice

Written by sctunisie no comments

To prepare Silica Aerogel the Sol-gel process is used. The chemical step is the first one to obtain a gel in alcoholic or acetonic medium. The aim of this work is the study of the influence ofsuch physico-chemical parameters on gel preparation and specially the acido-basic catalyst which gaverns the two steps of sol-gel process. For all precursors used (TMOS, TEOS et PEDS-Px) a reactionnal mecanism was given. Eventually the gelation time and the ageig of the gel were studied.

E. El Aloui, G.M. Pajonk

Sol-gel process, Silica, catalyst, precursors

Pages 607-620

Action des 5-amino-1-phényl-1,2,4-triazoles sur les éthers d’énols: Synthèse d’une nouvelle famille de triazolopyrimidines

Written by sctunisie no comments

5-amino-1-phenyl-1,2,4-triazoles 1, obtained by condensation of cyanamide with hydrazonate, react with ethoxymethylene derivatives of diethyl malonate 2, ethyl cyanoacetate 3 and malononitrile 4, to yield a new class of triazolopyrimidines.

F. Chabchoub, M. Kossentini, M. Salem

Hydrazonates, aminotriazoles, triazolopyrimidines

Pages 621-630

Action de l’hydrazine sur les 2-dialcoylaminométhylpropènenitriles: Synthèse de 2-cyano-3-dialcoylaminopropylhydrazines

Written by sctunisie no comments

The condensation of hydrazine with 2-dialcoylaminomethylpropenenitriles constitute a highly regiospecific reaction and an original route for synthesis of new 2-cyano-3-dialcoylarnino-propylhydrazines.

F. Yaccoubi, M.L. El Efrit, H. Zantour

hydrazine, dialcoylaminornethylpropenenitriles

Pages 631-638

Condensation des hydrazines fonctionnalisées sur des cétonitriles: Synthèse d’aminopyrazolo[1,5-a]pyrimidines et d’aminopyrimido[1,2-b]pyridazines

Written by sctunisie no comments

Aminopyrazolo[1,5-a]pyrimidines and aminopyrimido[1,2-b]pyrydazines were synthesized respectively by the condensation of 2-cyano-3-morpholinopropylhydrazine with α-ketonitriles and 2-cyano-3-dialcoylaminopropylhydrazines with β-ketonitriles in refluxing ethanol. 

F. Yaccoubi, M.L. El Efrit, H. Zantour

2-cyano-3-dialcoylaminopropylhydrazines, ketonitriles

Pages 639-645

Contribution à l’étude chimique d’hyparrhenia hirta L.

Written by sctunisie no comments

Six products have been isolated for the first time from the leaves and flowers of Hyparrhenia hirta (L.) Stapf (Andropogon hirtus) : tricosane; vanillin; 4-hydroxybenzaldehyde; 12,14-tritriacontandione; β-sitosterol and 3-O-β-D-glucoside sitosterol. Their structures were determined by spectroscopic methods.

H. Ben Salah, M. Bouaziz, A. Bahroun, M. Damak, A. Mc Killop, M. Simmonds

Hyparrhenia hirta, Gramineae, leaves, flowers, tricosane, 12,14- tritriacontandione, vanillin, 4-hydroxybenzaldehyde, β-sitosterol, 3-O-β-D-glucoside sitosterol

Pages 647-652

Contribution à l’étude structurale des composés de Centaurea dimorpha

Written by sctunisie no comments

Three extracts from flowers and stems of Centaurea dimorpha showed anti-Giardia, anti-oxydant, anti-inflammatory and anti H.I.V. activities. Two lignans, one alcane and four triterpens have been isolated from flowers and leaves of Centaurea dimorpha (Asteraceae). By means of spectroscopic methods (MS, IR, UV, 1H and 13C NMR and NOE difference sequence), their structures were established as arctigenin, arctigenin-4'-glucoside, tricosane, (β-amyrin, taraxasterol, sitosterol-3-O-β-D-glucoside and poriferasterol.

N. Damak, H. Ghorbel, A. Bahroun, M. Damak, A. Mc Killop, M. Simmonds

Centaurea dimorpha, Asteraceae, flowers, leaves, stems, lignans, alcane, triter-pens

Pages 653-658

Synthèse, étude structurale et pyrolyse de bis-spiro-Δ1-pyrazolines. Synthèse d’une spiro-Δ3-(1,3,4)oxadiazoline

Written by sctunisie no comments

[1,3]Dipolar cycloaddtion of 2-diazopropane on 2,6-dibenzylidenecyclohexanone 2 done at 0°C lead to tow bis-spiro-Δ1-pyrazolines: diastereoisomers 3 and 4. The same addition reaction carried out at -50°C gave in addition to adducts 3 and 4 and for the first time a new spiro-Δ3-(1,3,4)oxadiazoline with an inverse regiochemical way. The pyrolysis of 3 and 4 gave the ethylenic derivatives 6 and 7.

N. Boukamcha, M.T. Martin , A. Khemiss

2-diazopropane, bis-spiro-Δ1-pyrazolines, spiro-Δ3-(1,3,4)oxadiazoline

Pages 659-670

Stereoselective synthesis of 2-alkylidene-4-ketonitriles and -4-ketoesters

Written by sctunisie no comments

Conjugated addition of nitroalkanes to the Baylis-Hillman acetates 1b and 2b in the presence of NaOH (0.45N) in THF gave 2-alkylidene-4-nitronitriles 3-(Z,E) and -4-nitroesters 4-(Z,E) which were further converted via the Nef reaction into the corresponging 2-alkylidene-4-ketonitriles 5(Z,E) and -4-ketoesters 6-(Z,E) in high stereoselectivity and good yields.

S. Hbaïeb, H. Amri

Pages 671-681

Rss feed of the category