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
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
Dehydroascorbic acid reduction by thiols is carried out using classical and differential polarography. Electrochemical behaviours of reagents: ascorbic, dehydroascorbic, glutathione. British Anti Lewisite, are examinated, also the analytical advantages of this method.
C. Regnault Roger
The selectivity coefficient kAl/H relating to the fixation of aluminum ions on a sulfonic resin Duolite C20 is determined in nitric medium. Exchange kinetic in the resin column is expressed by the height of transfer unit.
M. Feki, H. Ayedi
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
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
Tin oxide and Zinc-Cadmium sulfide films were prepared by airless Spray. With this technique the growth rate is higher than by pneumatical Spray. The efficiencies of the Solar cells CdS/Cu2S and Cd0.9Zn0.1S/Cu2S are respectively about 2.6 % and 3.2 %.
M. Dachraoui, S. Belgacem, R. Bennaceur, H. Latrous
In recent years, many types of systems which enable the conversion of solar energy into electrical or chemical energy have been proposed. This work is a review of the electrochemical cells proposed in literature. For comparison, some results of photovoltaic cells are cited.
M. Dhahbi (ex. Hamdi)