Synthesis and chracterization of liquid crystalline materials as stationary phases in gas-liquid chromatography.

number: 
1267
إنجليزية
department: 
Degree: 
Imprint: 
Chemistry
Author: 
Nasreen Raheem Jber
Supervisor: 
Dr. Ammar H. Al-Dujaili
Dr.Shahbaz A. Maki
year: 
2005

Abstract:

This thesis consists of the synthesis of new liquid crystalline compounds2-thiobutanoyl-5-[4-(4_-methoxybenzylideneamino)phenyl]1,3,4- oxadiazole 1e, 4-[4_-methoxyben- zylideneamion)benzoyloxy]propylbenzoate 2d and two new homologous series derived from 2,5-bis-[4-amino phenyl]-1,3,4-oxadiazole 3d, these are 2,5-bis-[4-(4_-alkoxybenzylideneamino)phenyl]-1,3,4-oxadiazole 3e1-3i1 and 2,5-bis-[4-(4_-alkoxybenzanilide)phenyl]-1,3,4-oxadiazole 3e2-3i2. formula mentioned in the original abstract (3e2,f2,g2,h2, i2).The characterization of the synthesized compounds using FTIR and 1HNMR spectroscopy and the liquid crystalline properties of the prepared compounds which were verified using differential scanning calorimeter (DSC) and hot-stage polarizing microscope were discussed. The relation between the liquid crystalline behavior with chemical constitution was discussed on the basis of introduction of the heterocyclic unit, i.e., 1,3,4-oxadiazole. It was found that the replacement of aromatic rings by heterocyclic moiety play an important role in effecting the planarity, polarizibility and linearity which in turn effecting the thermal liquid crystalline stability. Compounds 1e and 2d were used as stationary phases in gas chromatography for separation of positional isomer hydrocarbons (o-, m-, p-cresol) and poly aromatic hydrocarbons ( naphthalene, flourene, phenanthrene and anthracene). Stationary phases for gas chromatography were prepared by loading the above compounds on solid support ( chromosorb W/AW 60-80 mesh) at 20