J. Phys. IV France 122 (2004) 171-175
Synthesis, characterization and intramolecular cyclisation study of three new liquid crystalsB. Saïdat1, M.H. Guermouche2 and J.-P. Bayle3
1 Centre Universitaire, Laghouat, Algérie
2 Institut de Chimie, BP. 32 El-Alia, Bab-Ezzouar, Alger, Algérie
3 Laboratoire de Chimie structurale, ICMO, Bât. 410, Université de Paris-Sud, 91405 Orsay Cedex, France
Internal cyclization of three new phenyldiazene liquid crystals (R is an alkyl substituent with 4, 6 or 8 carbons) with activated methylene group in the ortho position to the diazo linkage was studied . The initial liquid crystals was synthesised and characterized by 1H NMR, electrospray mass spectrometry and differential scanning calorimetry. The final compound was characterized by 1H NMR and differential scanning calorimetry. The kinetic of cyclization was studied at different temperatures and followed by reversed phase HPLC and a UV detection. For all the temperatures used, it appeared that the cyclisation was a first order reaction for the three compounds. The Arrhenius plot (ln reaction constant k against 1000/T) gave the mean activation energy of the cyclisation.
© EDP Sciences 2004