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
