JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Reaction of amines on hydrazonates

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1.2.4-triazoles have been synthetized by reaction of aromatic amines on hydrazonates of type 2b. The mechanism has also been studied and the corresponding products were identified by I.R. and 1H NMR spectroscopy.

M. Benkhoud, B. Baccar

Pages 3-10

Kinetics of water vapor diffusion in activated alumina

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The transient diffusion of water vapor on activated alumina is analyzed by the Weiz equation. It is found that this one parameter model describes well the sorption kinetic and provides an easy method for calculating the effective diffusion coefficient for the isobaric-isothermal process. The effective diffusion parameter is sufficient to describe the entire kinetic curve, at short and long times. A comparison of the general solution of the diffusion equation with this relation is done. It shows a weak difference between them. From the diffusion coefficients determined at different temperatures an activation energy is calculated which agrees well with reported values, indicating an increase by a factor 2 when the temperature is increased from 39 to 80°C.

M. Baguenne, A. Bellagi

Pages 11-23

Crystal growth of calcium sulfate dihydrate

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Crystal growth of calcium sulfate dihydrate has been investigated at 30°C using constant composition techniques in the supersaturation range 0.35 - 0.60. The kinetic of this process has been interpreted according to the spiral growth model proposed by NIELSEN.

S. Ghorbel, H.F. Ayedi, J.C. Heughebaert

Pages 25-34

Water pression effect on linear chains sodium orthophosphates condensation

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When orthophosphates starting materials are used to prepare condensed tripolyphosphates at 400°C, pyrophosphates and trimetaphosphates appear as intermediate compounds. High water pressure experimental condition affects the conversion reaction; it acts as catalysts in hydrolysis of cyclic trimetaphosphate and consequently accelerates and increases the tripolyphosphate polymerization.

M. Ben Amor, S.S. Romdhane

Pages 35-40

Synthesis of mixed alkali acid sulphates Cs1-xRbxHSO4 (0<x<1)

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Some compositions of solid-solution Cs1-xRbxHSO4 in the CsHSO4-RbHSO4 system have been synthesized by two methods :

  • Single crystals were grown by slow evaporation at 300K in aqueous solution by mixing in appropriate molar ratios Cs2SO4 and Rb2SO4 in sulfuric acid and adding a little water.
  • Cs1-xRbxHSO4 (0.1 < x < 0.9) materials have been synthesized by melting mixing of CsHSO4 and RbHSO4 powders and quenching in liquid nitrogen.

The unit-cell dimensions have been determined by using X-Ray powder patterns, Weissenberg and Precession methods. A comparison between density measurements from pellets mass determination and from unit cell parameters calculation (X-Ray results) allows to comfort the unit-cell parameters determination and the unit-cell parameters derived from a least-squares treatment of powder data. A rough draft of phase diagram of binary CsHSO4-RbHSO4 is presented.

T. Mhiri

Pages 59-71

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