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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/3405

Authors: Yonas, Bekele
Advisors: Ignacio J. Villar Garcia(Dr.)
Keywords: Ionic liquids
phenanthrolinium ionic liquids
metal complex solubility
homogeneous catalysis
Copyright: May-2011
Date Added: 17-Jul-2012
Publisher: Addis Ababa University
Abstract: Ionic liquids (ILs) are salts with melting points below 100oC and have remarkable and designer flexible physicochemical properties that offer distinctive performance advantages in a variety of synthetic, catalytic, and electrochemical applications. They are widely used as green alternatives to conventional environment polluting volatile organic solvents (VOCs) due to their negligible vapor pressure. However, their application in areas like catalysis is limited by the limited number of cations on which the majority of ILs in common use is based and due to the low solubilities of organometallic compounds in these groups of ILs. Their green credentials are also being put into question as the interest in ILs increases. Hence designing new ILs for a given application should also be accompanied by improvements in the methodology of their preparation with respect to economics of preparation, environmental impact and cumulative energy demand (CED). In a current work done in our laboratory, [CnPhen]X (X= Br-, PF6 -, Tf2N-) ILs have been synthesized following a similar procedure to commonly used ILs and they exhibited good solubilities for phenanthroline and phenanthroline - metal complexes. Tetrafluoroborate ILs normally exhibit low melting points and low coordinating abilities that are desired for catalytic reactions. For this study, we have synthesized a range of new [CnPhen]BF4 ILs with varying alkyl chains. Even though, the new water miscible [CnPhen]BF4 ILs could be synthesized according to the conventional procedure for the synthesis of other water miscible BF4 - containing ILs, we developed a new simple anion metathesis procedure, which has cut down reaction times, improved yields and bypassed the difficult by-product separation and product purification steps. [CnPhen]BF4 ILs exhibited good solubilities for phenanthroline and a wide range of phenanthroline based metal complexes. Their melting points were found to be relatively lower than its halides, PF6 - and some of Tf2N- containing analogues and followed the same trend with alkyl chain length of the cation as its [CnPhen]Br precursor. Furthermore, these ILs are found to be soluble in a larger number of organic solvents than their analogous salts, which offer flexibility for application in a number of reaction and catalysis schemes.
Description: A thesis submitted to school of graduate studies of Addis Ababa University in partial fulfillment of the requirements for the Degree Of Master of Science in Chemistry
URI: http://hdl.handle.net/123456789/3405
Appears in:Thesis - Chemistry

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