Synthesis of disc-shaped liquid crystals containing azo chromophores

Low, Kim Boon (2008) Synthesis of disc-shaped liquid crystals containing azo chromophores. Universiti Malaysia Sabah. (Unpublished)


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The objective of this dissertation is to synthesis disc-shaped liquid crystals containing azo chromophores, 2,3,6,7,10,11-hexakis {[ 4-( 4-acety 1 phenylazo )phenoxy ]hexyIoxy } triphenylene). This disc-shaped liquid crystal is synthesized from the starting material 4 aminoacetophenone to 4-( 4-hydroxypheny lazo )acetophenone via diazo coupling reaction. From 4-( 4-hydroxyphenylazo )acetophenone,1-bromo[ 4-( 4-acetylphenylazo) phenoxy]hexane is synthesized via esterification with the potassium carbonate and the catalyst of potassium iodide. Then 1 ,2-bis{ [4-( 4-acetylphenylazo )phenoxy] hexyloxy} benzene IS synthesized via esterification from 1-bromo[ 4-( 4- acetylphenylazo )phenoxy] hexane with catechol, potassium carbonate and potassium iodide. Finally the disc-shaped liquid crystal is synthesized ferric chloride oxidative trimerisation of 1 ,2-bis {[ 4-( 4-acetylphenylazo) phenoxy]hexyloxy} benzene. Melting point of each intermediate is determined by Capillary Melting Point Exterminator. The melting point of compound 1 is in the range or 198-202°C, compound 2 is 120-125°C, and compound 3 is 122-125°C. Fourier Transform Infrared (FT-IR) is used to determine the presence of functional group of each intermediate and the finl compound. The functional groups that reveals in the final compound are alkyl, aromatic, ketone, methyl, and ether. ¹H-Nuclear Magnetic Resonance ¹H-NMR) is utilized to reveal number of magnetically distinct atoms of compound 3. The resulted spectrum produced was not indicates the presence of compound 3 but it was only compound 2. Differential Scanning Calorimetry (DSC) is used to determine the phase transition temperature and enthalpy of the compound 3. The thermogram produced shows only single peak that present in both heating and cooling cycle with melting temperature (Tm) is 123.53 °C and the cooling temperature (Tc) is 102.7 °C.

Item Type: Academic Exercise
Uncontrolled Keywords: disc-shaped, liquid crystal, azo chromophores, synthesis, Fourier Transform Infrared, Differential Scanning Calorimetry, thermogram
Subjects: T Technology > TP Chemical technology
Divisions: SCHOOL > School of Science and Technology
Date Deposited: 19 May 2014 02:29
Last Modified: 13 Oct 2017 03:11

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