The evaluation of the behaviour at the air/water mixtures interface of a new series of oligoethoxylated monoalkyled F-alkyl α-bromoesters of general formula RF-CHBr-CO-O-(C2H4O)2-RH has been investigated at 20°C by measurement of surface tension (γs) of the water/ethanol surfactant solution. Critical micelle concentrations (CMC), surface excesses (Γ) and molecular areas (A) have been obtained from these measurements. The study of these physicochemical parameters allowed us to establish the relationship between the surfactant molecular structure and its interfacial properties. In addition we have studied in this work the variation of γs, CMC and Γ with the amount of ethanol used in the mixed ethanol/water solvent. This study allowed us to determine by extrapolation the theoretical values of γs, CMC and Γ in pure water, which could not be obtained experimentally regarding the low solubility of these surfactants in water.
B. Jedidi Yaïch, K. Debbabi, R. Naejus, C. Damas, R. Coudert, A. Baklouti
F-alkyl, oligoethoxylated, nonionic surfactants; solution behaviour; surface properties
Synthesis of novel 3-cyanopyridine-2(1H)-thiones, thieno[2,3-b]pyridines and pyrazolo[3,4-b]pyridines. Michael addition of ethyl 4,4,4-trifluoroacetate-3-oxobutanoate and 1,1,1-trifluoropentan-2,4-dione on arylmethylenecyanothioacetamides 1 in refluxing ethanol leads to the corresponding 3-cyano-pyridine-2(1H)-thiones 4 and 7. The synthesis of a new series of pyrazolo[3,4-b]pyridines 9 and thieno[2,3-b]pyridines 11 by alkylation and cycloaddition of the synthetized products 4 and 7 is reported. The structure of obtained products was determined on the basis of their IR and NMR data.
S. Askri, M.L. Efrit
arylidenecyanothioacetamides, pyridine-2(1H)-thiones, Thorpe-Ziegler reaction
Investigation of methanolic extract from Matthiola longipetala (ssp. livida) (Del.) Maire Brassicaceae of Tunisian origin, led to the isolation of methylfirulate-4’-O-β-D glycoside 1 together with 2-O-methyl α-D-fructofuranose tetraacetate 2 as well as α-D-glycopyranose pentaacetate 3 and β-D-glycopyranose pentaacetate 4, all structures were established using 1 and 2D NMR experiments, carbohydrates were identified via their acetylated derivatives.
S. Hammami, I. Khoja, N.N. Mrad, H. Ben Jannet, M.A. Hamza, Z. Mighri
Matthiola longipetala (ssp. livida) (Del.) Maire, Brassicaceae, 4’-O-β-D-glycopyranosyl-methylfirulate 1, 2-O-methyl α-D-fructofuranose tetraacetate 2, α and β-D-glycopyranoses pentaacetates 3 and 4
The high yield, metal-free synthesis of furanyl-isosorbide and -isomannide derivatives is described. 1H NMR study highlighted both the introduction of a dianhydrohexitol substituent and a decrease of aromaticity with concomitant increase of the dienic character of the furan.
R. Medimagh, H. Ben Abderrazak, I. Aouam, I. Gabsi, S. Marque, T. Ben Ayed, S. Chatti, D. Prim
Two compounds LixAlxSi3-xO6 (x = 1,05 (I) et x =1,44 (II)), lithium aluminosilicate (LAS), were grown by conventional high-temperature, solid-state methods. The compounds have the ß quartz-type structure. Si4+ cations are replaced by Al3+ and the charge is compensated by the incorporation of Li+ into the main channel of the structure. The structure consists of a three-dimensional aluminosilicate framework. The distribution of Si and Al in the tetrahedra is completely random. The Al and Si atoms are disordered on a single site. The refinement led to reliability factors lower than those of all the isotype structures. The discussion of the stability of the related compounds as well as the evolution of the crystallographic parameters are been resumed in this work.
M. Graia, A. Driss
LixAlxSi3-xO6, quartz β, DRX, monocristal
This work aims to study the activation of Tunisian smectite clay with sulfuric acid and to investigate the catalytic role of the sulfuric acid adsorbed onto its surface in the stearic acid esterification by ethanol. The structural modifications brought to the clays after activation have been identified by X-ray diffraction (XRD) and Infrared spectroscopy (IR). The chemical analysis by microanalysis X (MX) reveals the presence of the sulfuric acid adsorbed onto clays surface after activation. It has been shown that these clays, used as catalysts for esterification of stearic acid with ethanol, show two types of catalytic activities. A catalytic activity of surface related to the cationic exchanges and another important related to the sulfuric acid adsorbed onto clay surface. These catalysts show a high stability allowing them to be used several cycles with a sufficient activity.
S. Bouguerra Neji, M. Trabelsi, M.H. Frikha
Activation, Adsorption, Sulfuric acid, Smectite, Esterification
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