Synthesis and characterization of rodshaped liquid crystals with azobenzene as mesogenic cores

Moho Fadzrul Hasrie, (2010) Synthesis and characterization of rodshaped liquid crystals with azobenzene as mesogenic cores. Universiti Malaysia Sabah. (Unpublished)

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Abstract

Rod shaped liquid crystals is probably the most important type of liquid crystals nowadays. This is because, rod shaped liquid crystals serve as the cores of the most complicated liquid crystals which means that it can be used to synthesized other types of liquid crystals. In this study four types of organic reactions were conducted in order to obtain the target liquid crystals molecule. The first reaction is the Diazonium coupling reaction. The starting material which is 4-Aminoacetophenone was coupled with phenol to yield compound 1 which is 4-( 4-Hydroxyphenylazo) acetophenone. The second reaction is the Williamson's ether synthesis reaction. In this reaction, compound 1 was reacted with Ethyl-6-bromohexanoate to produce compound 2 which is 6-[4-(4- Acetylphenylazo) phenoxy] hexanoate. The third reaction is the alkaline hydrolysis reaction. In this reaction, compound 2 was reacted with potassium hydroxide to yield 6- [4-(4-Acetylphenytazo) phenoxy] hexanoic acid, compound 3. The last reaction done was esterification reaction. Compound 3 was reacted with resorcinol in the presence of DCC and DMAP to yield the target molecule which is {[4-(4-Acetylphenylazo ) phenoxy] pentyl} benzoate, compound 4. The percentage yield of the target compound obtained was calculated to be 51.02 %. The functional group of the intermediates and the target compound was determined using FT-IR. The phase transition temperature and phase transition enthalpy of the target compound was determined using DSC. The Phase transition temperatures are 123.88 °C for endothermic and 99.97°C for exothermic. From the DSC thermogram, it can be observed that the target compound has mesophase characteristic which means that the target compound has liquid crystals phase.

Item Type: Academic Exercise
Uncontrolled Keywords: liquid crystals, rod shaped, Diazonium, alkaline hydrolysis
Subjects: Q Science > QD Chemistry
Divisions: SCHOOL > School of Science and Technology
Depositing User: Unnamed user with email storage.bpmlib@ums.edu.my
Date Deposited: 16 May 2016 05:17
Last Modified: 30 Oct 2017 02:34
URI: http://eprints.ums.edu.my/id/eprint/13155

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