JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

A comparative study of Rayleigh and Raman collisional diffusion from gaseous deuterium

Written by sctunisie no comments

We have studied the collisional Rayleigh and Raman intensity for densities between 18 and 130 Amagat at 293 K. The depolarisation ratios have been compared to those calculated with dipole-induced dipole model taking into account the anisotropy of molecules. The agreement between theory and experience is rather good for low densities.

H. Khalfallah, R. Boukhris, A. Gharbi

Pages 57-64

Short communication: Setting up A band E microwave and tests on KH2PO4 phase transition

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A band E microwave measurement device has been set up and tested. The ferroelectric-paraelectric phase transition of a KH2PO4 monocristal has been observed at a temperature of 123 K for a frequency of 70 GHz. The extreme values of complex permittivity during the transition have been determined.

H. Zangar, M.S. Haouat

Pages 65-67

Synthesis of benzofuro (3-2b) benzofuran and benzofuro (2,3-b) benzofuran derivatives by transposition of Claisen acido catalyses

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Claisen rearrangement of 1,4-diaryloxy 2-butynes in the presence of protonic acid yields first derivates of benzofuro (3,2-b) benzofuran. These products could be transformed to their isomers: derivates of benzofuro (2,3-b) benzofuran by an acidic catalysed shift. A mechanism is proposed for this reaction. 

M. Rammah, B. Laude

Pages 3-13

Contribution to the study of Lepidium sativum (cruciferae). Structure of a new seed compound: Lepidine

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Four compounds were isolated for the first time from the seeds of Lepidium sativum (cruciferae) with alkaloids extraction method: The ethyl-sinapinate 1. the N-N' dibenzylthiourea 2, the N-N' dibenzylurea 3 and a novel compound which we called the lepidine 4. Their structure has been established by spectroscopic means. 

A. Bahroun, M. Damak

Pages 15-24

Analysis of the performance of an absorption heat pump

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After a recall on the principle of on absorption heat pump and a review of a test unit (power: 1 kw) operating with the couple LiBr-H2O, the authors present absorption heat pump performance. The results show that :

  • Exchanger area is a limitant factor of exchange
  • The performance of absorber increases with solution flow rate and decreases with the increase of concentration
  • The experimental COP is less then theoretical COP
  • The level of up-grading 140° from industrial heat recovery (60-80°C) is possible with a COP about 1,4.

S. Gabsi, R. Bugarel

Pages 41-49

Short communication: Infrared study of the adsorption of NO, CO and NO + CO on α-Fe2O3

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An infrared spectroscopic study of the adsorption of NO, CO and NO + CO on α-Fe2O3 was carried out in order to identify chemisorbed species and discuss adsorption sites. Stable nitrate species are formed on the surface at beam temperature (b.t.) when NO is adsorbed. Depending on the pressure, NO adsorbs at b.t. also to form Fe3+ (NO) species. Only a weakly adsorbed species, coordinated with a cationic sites to form different types of carbonates is observed at high temperature adsorption (473 - 523 K). In the presence of NO + CO mixture, stable nitrate ions are formed when temperature is increased from b.t. to 423 K. At higher temperature (473 - 523), NO and CO mainly chemisorb as nitrates and carbonates in to an adsorption of NO on partially reduced cationic sites : Fe(3-δ)+(NO); Fe2+(NO).

H. Batis, N. Harrouch, A. Ghorbel

Pages 51-58

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