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