P. V. Rathod et al.
3.2.2 Catalytic Study of CC-SO3H for Fructose, Sucrose,
and Glucose to 5-HMF Conversion in the Presence
of Tri-cationic Ionic Liquids
and 130 °C, with increasing the reaction temperature the
5-HMF yield increase from 24%, 61%, and 77% respectively.
But when we have done above reaction at 150 °C, we got a
decrease in 5-HMF yield. The decrease in 5-HMF yield is
possible because the 5-HMF is unstable at high temperature
as it could be transformed into levulinic acid by alcoho-
[40]. Table 2 shows the influence of reaction temperature on
Table 2 that the increase of temperature from 120 to 140 °C
yield of 5-HMF increased from 36 to 58%. Increasing reac-
tion temperature upto160 °C slightly decreases 5-HMF yield
may be due to the instability of 5-HMF at high temperatures.
Therefore, 140 °C was considered to be the optimum reac-
tion temperature for this system.
Above results show a conversion of fructose, sucrose, and
glucose to 5-HMF with 93%, 72%, and 51% yield, respec-
tively obtained in [GLY(mim)3][OMs]3 RTIL at 120–140 °C,
showing used catalytic system is highly efficient for sugar to
5-HMF conversion. The effect of the different anion (ionic
liquids) with metal-free co-catalyst used for dehydration
reaction of fructose, sucrose, and glucose. For comparison
purposes, we studied a neat system for the same reaction.
In which we observed that without solvent the correspond-
ing 5-HMF yield is very high; such that the fructose to
5-HMF selectivity increase resulted in 100% conversion
and the corresponding isolated reached 93% 5-HMF yield.
However, under the same reaction but in the absence of
[GLY(mim)3][OMs]3 ionic liquid, no 5-HMF product forma-
tion took place. Moreover, we observed that in presence of
[GLY(mim)3][Cl]3, [GLY(mim)3][PF6]3 and [GLY(mim)3]
[Br]3 the dehydration of sugar to 5-HMF reaction rate is low
as the isolated 5-HMF yield was very low as compared to
[GLY(mim)3][OMs]3 (RTIL).
Table 3 shows the effect of CC-SO3H catalyst loading on
the fructose to 5-HMF conversion. In which we observed
that when the catalysts amount was increased from 0.025,
0.050 and 0.100 g the yield of 5-HMF improved from 78, 85
and 97% (isolated). But further increasing catalysts loading
above 0.100 g doesn’t give a higher yield of 5-HMF. The
decrease in activity possibly because of the area and the
surface acidity on the catalyst decreases due to the increase
of CC-SO3H concentration [44]. We have also studied the
But when we combined the above mentioned ionic liquids
(RTILs) and CC-SO3H co-catalyst, we observed the corre-
sponding 5-HMF yield is high. We observed the dehydration
of fructose with [GLY(mim)3][PF6]3, [GLY(mim)3][Cl]3 and
[GLY(mim)3][Br]3 (RTILs) with co-catalyst CC-SO3H at
100 °C gives 5-HMF yield of 56%, 71% and 61% (isolated)
respectively, using a similar reaction condition. In the pres-
ence of [GLY(mim)3][Cl]3 ionic liquid, we got a high yield
of 5-HMF as compared with other ionic liquids. Further,
we investigated different reaction parameter effect on dehy-
dration of fructose, sucrose, and glucose to 5-HMF in the
presence of [GLY(mim)3][Cl]3 (RTIL). Initially, we chose
fructose as the substrate. As expected, as the temperature
increases, the conversion of fructose increases with increas-
ing temperature. More importantly, the yield of 5-HMF not
only increases, but also the reaction time decreases with
increasing temperature. As we observed after the 24 h at the
low temperature of 80 °C, the obtained 5-HMF yield was
32%. However, by increasing the reaction temperature to
100 °C, just within 8 h the 5-HMF yield increased signifi-
cantly to 71%, indicating that higher temperatures improve
reaction rate resulting in an increase in 5-HMF yield in a
shorter time. When further reaction temperature increased
up to 130 °C, the yield of 5-HMF increased to 97% within
3 h. But, when we increased reaction temperature up to
150 °C, the yield of 5-HMF slightly decreases. So finally,
the reaction temperature of 130 °C is considered to be the
most suitable for the higher productivity of 5- HMF.
Table 2 Study of fructose, sucrose, and glucose to 5-HMF using CC-
SO3H Catalyst in various temperature
Entry Substrate Ionic liquid
(IL)
Temp Time (h) Yield (%)HMFa
oC
1
2
3
4
5
6
7
8
9
10
Fructose [GLY(mim)3]
[Cl]3
80
24
12
3
32.6
71.4
97.0
92.1
24
Fructose [GLY(mim)3] 100
[Cl]3
Fructose [GLY(mim)3] 130
[Cl]3
Fructose [GLY(mim)3] 150
3
[Cl]3
Sucrose [GLY(mim)3]
[Cl]3
80
24
15
3
Sucrose [GLY(mim)3] 100
61
[Cl]3
Sucrose [GLY(mim)3] 130
[Cl]3
77
Glucose [GLY(mim)3] 120
5
36
[Cl]3
Glucose [GLY(mim)3] 140
[Cl]3
5
58
Glucose [GLY(mim)3] 160
5
54
[Cl]3
Reaction conditions: fructose (0.2 g) / Sucrose (0.2 g) / glucose (0.2),
[GLY(mim)3][Cl]3 IL (0.5 g), CC-SO3H catalyst (0.1 g), without sol-
vent, N2 atmosphere
Similar results were observed for sucrose to 5-HMF con-
version reaction. When the reaction was done at 80, 100
aIsolated yield
1 3