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تحضير وتشخيص ودراسة السلوك البلوري السائل لبعض من مشتقات المركبات الحلقية الغير متجانسة الجديدة == Synthesis ,Characterization and Liquid Crystalline Behavior of Some New Heterocyclic Derivatives
Author name:
فاطمة احمد عبد
Supervisor name:
جمبد هرمز توما | نسرين حسين كرم
General topic:
Chemistry
Specific topic:
Chemistry
Degree:
Master
University:
University of Baghdad
Language:
English
University location:
Baghdad
First pages:
25T1825 - p.pdf
Abstract:
This work includes synthesis , characterization and study the liquid crystalline behavior of some new heterocyclic compounds , as follows : Synthesize three series containing 1,2,4 - triazole ring with imine groups [X]a - g - [XII]a - g and thiazolidin - 4 - ones [XVII]a,b .The isophthalic or terephthalic acid is converted to a corresponding ester compounds [I]a,b by reflexing with methanol in H2SO4 as a catalyst . The condensation of the later compound [I]a,b with hydrazine hydrate to yielded acid hydrazide compounds [II]a,b , which were reacted in two routes : a) Reaction with 4 - (4 - methoxybenzoyloxy)benzaldehyde [XIII] to give new schiff bases [XIV]a,b which were reacted with thioglycolic acid under cyclization reaction to yield new thiazolidin - 4 - ones compounds [XVII]a,bb) Reaction with ammonium thiocyanate or with phenyl isothiocyanate to give a corresponding thiocarboamide [III]a,b , [IV] as intermediate compound for synthesis 5 - thiol - 1,2,4 - triazoles under basic medium . Also the compound [III]a,b could be synthesized from the reaction directly of ester compound [I]a,b with thiosemicarbazide .The 3 - substituted - 5 - thiol - 1,2,4 - triazoles [V]a,b and [VI] converted to 3 - substituted - 5 - hydrazino - 1,2,4 - triazoles [VII]a,b , [VIII] by reflux with hydrazine hydrate . Finally the later compounds reacted with ketone and different aromatic aldehydes to give new Schiff bases [X]a - g , [XI]a - g , [XII]a - g , [XV]a,b and [XVI] .The synthesized compounds were characterized by FTIR , 1HNMR and mass spectroscopy (of some of them ) .The study of liquid crystalline properties (by DSC and polarizing microscope) of the synthesized compounds showed : a) All the member of series [X]a - g exhibited mesomorphic behavior except [X]g . The compounds [X]a and [X]f showed enantiotropic nematic phase while the compounds [X]c and [X]d showed dimorphism smectic C and nematic phases . In addition the compound [X]b showed dimorphism enantiotropic smectic B (high ordered) and nematic phases. Finally [X]e showed only enantiotropic smectic A phase .b) All the members of series [XI]a - g and [XII]a - g did not show any liquid crystalline behavior .c) The Schiff base 1,3 - phenylene - bis{5 - N - [4 - (4 - methoxybenzoyloxy) benzylidene hydrazinyl] - 4H - 1,2,4 - triazol - 3 - yl} [XV]a showed enantiotropic nematic mesophase , while the Schiff bases [XIV]a,b , [XV]b and [XVI] did not show any liquid crystalline properties . Also , the thaizolidinone compounds [XVII]a,b did not show any liquid crystal properties .This work can be summarized by the following , Schemes I and II :
