Spiro-∆1pyrazolines 3a-e have been synthetized by 1,3-dipolar cycloaddition of some arylidenes of indan-1’,3’-dione 1a-e with ethyl diazoacetate 2. On heating under reflux, the spiroadducts 3a-e lose nitrogen molecule, thus being converted into spirocyclopropanes 4a-e. The proposed regio- and stereochemistry of cycloadducts 3a-e and 4a-e have been elucidated by 1H and 13C NMR.
N. Wannassi, M.M. Rammah, M.B.r Rammah, K. Ciamala
1,3-dipolar cycloaddition, ethyl diazoacetate, spiro-pyrazolines, spirocyclopropanes
New spiro-compounds basis of isoquinoline-1,3-dione were prepared by microwave-assisted 1,3-dipolar cycloaddition reactions with azomethine ylides. The reactions performed under microwaves were compared with the same reactions conducted under the classical conditions of thermal heating.
A. Bahy, N. Jegham, Y. Kacem, J. Marrot, B. Ben Hassine
Isoquinoline-1,3-dione, 1,3-dipolar cycloaddition, microwave, Azomethine ylides
Solution polycondensation of furanic dihydrazides with different bridging groups, in conjunction with various aromatic diisocyanates, gave high yields of a novel series of furanic poly(acylsemicarbazide)s with high molecular weights. The polymers were characterized by solubility tests, viscosity measurements, 1H NMR, 13C NMR and FTIR spectroscopies and thermogravimetric analysis. The poly(acylsemicarbazide)s obtained had inherent viscosities in the range of 0.23-0.70 dL/g, and were easily dissolved in common organic solvents. The glass-transition temperatures of these polymers were recorded between 135 and 200°C. Decomposition temperature for 10% weight loss all occurred above 350°C in nitrogen atmosphere. Preliminary tests on films of all polymers indicated that these materials were flexible and tough.
I. Ghorbel, M. Abid, V. Massardier, S.r Abid, R. El Gharbi
Furan polymers; Poly(acylsemicarbazide)s; Diisocyanates; Polycondensation; Biomass
The reaction of bis-amidrazones 1 with oxalyl dichloride and carbone disulfide provides respectively a convenient access to the new bis-1,3,4-triazinoalkanes 2 and bis-1,3,4-triazoloalkanes 3. The structure of all obtained products is confirmed by NMR (1H, 13C) and IR spectroscopy.
S. Hamzaoui, M. Kossentini
bis-1,3,4-triazinoalkanes, bis-1,3,4-triazoloalkanes, bis-amidrazones, oxalyle dichloride, carbone disulfide
Ring opening of diepoxides using three kinds of fluorinating reagents has been realized. Regioselectivity of the hydrofluorination depends essentially on acidity of the used reagent. Thus, highest yields and best selectivity were obtained with the less acidic reagent.
L. Tebourski, N. Grayaa-Jaoued, A. Hedhli
diepoxide, hydrofluorination, fluorohydrin
Kinetics of the addition of OH- to ethyl-2-cyano-3-phénylacrylate 1a have been determined by UV-vis spectroscopy in water at 20°C. The second-order rate constant (k) is employed to determine the electrophilicity parameter (E) of 1a as defined by the equation log k (20°C) = s (N +E) (Angew. Chem. Int. Ed. Engl., 1994, 33, 938-957). The increase in electrophilie brought about by the introduction of a second CO2Et group in 1a to give 1b is very large and equal to about 9 E units while that the transition from 1c to 1a is only of the order of 2,5 E units. This suggests that the two CO2Et group contributes very effectively to the resonance stabilization of the carbanion A.
N. Dhahri, T. Boubaker, R. Goumont
Electrophilicity Scale, Mayr Equation, Michael Acceptors
The objective of this study is the characterization of activated carbon prepared from a lignocellulosic natural residue which is a vegetation waste "seeds of Ziziphus spina-christi" of the central of Tunisia. The activated carbon was prepared by these conditions as follows: 3/4/1 (w/w) a water/KOH/coal ratio, 700°C carbonization temperature and 120 min activation time. Characterization of the activated carbon obtained was performed by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and specific surface. The adsorption properties of samples of carbons were studied from their adsorption isotherm of copper from aqueous solutions at 25°C. This study has resulted that the adsorption obeys the Langmuir isotherm as well the Freundlich isotherm with maximum adsorption capacity of about 104 mg /g.
A. Omri, M. Benzina
Ziziphus spina-christi seeds; activated carbon; Characterization; Adsorption
Composites membranes based on Nafion blended with Phosphatoantimonic acid (H3) exhibit high conductivities associated to enhanced thermo-mechanical performances as compared to Nafion. The preliminary tests performed on membrane electrode assembly (MEA) based on these composites membranes allowed for a given content in H3 i.e. 10% obtaining improved polarization curves as compared to the pristine membranes.
H. Ben Attia, J.C. Lepretre, J.Y. Sanchez, C. Iojoiu, J. Guindet, N. Bellakhal
Nafion 117®; Composites membranes, Phosphatoantimonic Acid, Mechanical reinforcement, PEMFC, Polarization curves
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