Synthesis of dicationic ionic liquids and their application as co-catalyst for fructose conversion / Suhaila Mohd Yaman

Suhaila , Mohd Yaman (2018) Synthesis of dicationic ionic liquids and their application as co-catalyst for fructose conversion / Suhaila Mohd Yaman. Masters thesis, University of Malaya.

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Abstract

In this study, six new imidazolium based dicationic ionic liquids (ILs) were successfully synthesized with one step process. These ILs were designated with three different positions of substituent of benzyl-imidazolium at ortho, meta and para on cationic site while tuning the counter anion with chloride and hydrogen sulphate anion. As a result, this unique combination between cation and anion dramatically impact towards the properties of ILs. The characterizations of all ILs were elucidated using 1HNMR, 13C-NMR, FT-IR and CHN elemental analyses. The thermal analysis of these ILs reveals the information of phase transition of glass transition (Tg), melting temperature (Tm), decomposition temperature (Td) and their high thermal stability. Further, the acidity properties were quantified by Hammet acidity function (Ho) that gives the information on the acidity strength of each ILs. These ILs also meet the criteria as catalyst as they were hydrophilic, high stability, acidic and can be recycled. The investigation was started with the screening process by using each IL as a catalyst in separate reaction. Each parameter such as time, temperature, catalyst loading was optimized and the transformation mechanism of fructose to HMF was rationalized. Besides, the reusability study had also been conducted. In addition, in–situ study by using 1H-NMR provides information on the selectivity of the ILs at a given time and temperature. The intrinsic properties of dipole moment and polarity that existed in the structural ILs were also discussed. The difference in position of ortho, meta and para substituent was proven to give a significant contribution and affecting the fructose dehydration process.

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