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Attempts to Green the Synthesis of Liquid Crystals

xu, zheng (2015) Attempts to Green the Synthesis of Liquid Crystals. MSc by research thesis, University of York.

Available under License Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 UK: England & Wales.

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This study presents several green approaches to the synthesis of liquid crystals. In the research, three types of reactions (esterification, Suzuki cross-coupling and amidation) have been considered. A series of sulfonated Starbons (mesoporous carbonaceous materials derived from polysaccharides) have been tested for esterification as catalysts. As a result, sulfonated Starbon was found to have selectivity for cis- and trans-isomer of 4-pentyl-cyclohexane carboxylic acid. Cis-isomer has priority in the reaction. With water-soluble carbodiimide as coupling agent, cyclopentylmethyl ether (CPME) as solvent, and microwave irradiation, a series of trans-4-n-alkyl-cyclohexane carboxylic acid 4-cyanophenol esters were synthesized and their liquid crystalline phase transition temperature was determined. Green metrics were applied to assess this reaction with respect to the traditional synthesis. A series of Starbon-Pd were tried in two different solvent systems (ethanol/water and CPME/water) as heterogeneous catalyst for Suzuki reaction. All the Starbon-Pd had a high activity in ethanol/water solvent system. In CPME/water solvent system, only Starbon-500-Pd had a good performance. Starbon-Pd catalyst could be reused approximately 3 times in the Suzuki reaction. With comparison, CPME has been proved that it was a better replacement for THF in Suzuki reaction. A mesoporous structured silica catalyst was applied to amidation for the purpose of generating liquid crystalline amides.

Item Type: Thesis (MSc by research)
Academic Units: The University of York > Chemistry (York)
Depositing User: Mr zheng xu
Date Deposited: 07 Aug 2015 11:17
Last Modified: 07 Aug 2015 11:17
URI: http://etheses.whiterose.ac.uk/id/eprint/9456

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