the production of thymoquinone from thymol and carvacrol

temperature (ºC)
carvacrol / (%30)H2O2
(molar ratio)
4.5 ml carvacrol (constant)
catalyst amount (g)
Table 7.7. Values of parameters
low value intermediate value high value
40
1
3ml
(%30)H2O2
0.05
50
2
1.5ml
(%30)H2O2
0.13
a Reaction conditions: Acetonitrile as solvent, 5 hours reaction time
7.3.1. Effect of Catalyst Amount
60
3
1ml (%30)
H2O2
The effect of catalyst amount on the carvacrol oxidation reaction was given in
Table 7.8. From the table, it was clear that by using 0.05 g catalyst at 50 ºC with a molar
ratio of 2 only 7.4% carvacrol conversion was obtained. An increasing amount of
catalyst weight from 0.05g to 0.13g or 0.2g has enhanced performance. Increment of
catalyst amount hardly improved the conversion. Increase in carvacrol conversion while
increasing catalyst amount indicates of reaction was catalytic in nature. This result was
also observed in phenol oxidation reactions (Maurya et al. 2003). In phenol oxidation
reaction, up to certain catalyst weight conversion was increased then no significant
increasing was observed. This can be explained by the saturation of active sites and this
was probably due to more rapid hydrogen peroxide decomposition at large catalyst
amount. When conversion increased with increasing catalyst amount higher amount TQ
was observed with small amount of THQ and BQ derivatives. With low catalyst
amount, reactions were more selective for TQ formation compared to higher catalyst
amount.
0.2
61