The synthesis of pyrazolenines derived from dissymetric monoactivated acetylenics of which the second substituant is n-alkyl has been realized stoechiometrically. This result was obtained by addition 1,3-dipolar of diazo-2 propane to the starting acetylenics. In the same way, all the photolysies of the mono-activated pyrazolenines have enabled us to get exclusively the expected mono-activated gemdimethylcyclopropene.
A. Khemiss, M. Franck-Neumann
The Z/E olefinic bond ration of enol ethers obtained by Oxy-Cope rearrangement of hetero-substituted 1,5-hexadienes reveals that the reaction is not governed by the free energy change for the conversion of a substituent from the equatorial to the axial position in the chair transition state but rather by the relative thermodynamic stability of the isomers Z and E.
R. Abdelhedi, M.L. Bouguerra, J. C. Pommelet, J. Chuche
Addition compounds of the type 1 : 1, 1 : 2 and 1 : 4 are obtained as a result of tin (IV) chloride action with cyclohexanol derivates in petrolium ether. Infrared study and elementary analysis confirm these results.
S. Jarraya, C. Devin
The oxidation of propylene over the Tin-Antimony oxide catalysts has been proved to be sensitive to the composition of the reactional mixture. This composition affects the stability of the catalyser during the reaction and the fonctionning of its busy centres.
B. Bejar, N. Zenaidi, A. Ghorbel
The low frequency Raman Spectra (0 - 350 cm-1) of [(CH3)2 NH2]2 Sn Cl6 (2MHS) and [(CH3)3 NH]2 Sn Cl6 (3MHS) were recorded on single crystals at room temperature. The Spectra have been assigned on the basis of group theory analysis of vibrations and in view of the previously reported structural data of these two hexachlorostannate compouds. Their corresponding structures are derived from the Fm3m antifluorite structure.
M.H. Ben Gozlen, Y. Mlik, A. Daoud
The vibrational study of potassium and ammonium disulfates by Raman and Infrared spectroscopy gives supplementary informations about the structure of these two crystals and shows that there is strong and dissymetric hydrogen bonds in these salts.
M. Damak, A. Daoud, A. Novak
The cubic β-Na3PO4 phase stabilized by calcium shows an order-disorder phenomenon, which is studied by means of electronic paramagnetic resonance.
A.W. Kolsi, J. Livage, M. Quarton
The fact that mixed potential of aluminum in a 0.1 N NaOH solution at 60°C is more negative when the metal is purer can be readily explained by potential v s. time plots and volumetric measurements. these are consistent with impurities behaving as microcathodes which shift the mixed potential of pure aluminum towards higher potentials, the corrosion velocity being enhanced correlatively.