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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7.4. Oxidation <strong>of</strong> Thymol<br />
Carvacrol <strong>and</strong> Thymol are aromatic monoterpenes, which can be found in <strong>the</strong><br />
essential oils <strong>of</strong> many aromatic plants. They are geometrical isomers. Their chemical<br />
structures are very similar as seen in Figure 7.14 (Martin et al. 1999).<br />
(a) (b)<br />
Figure 7.14. Structure <strong>of</strong> (a) Thymol <strong>and</strong> (b) Carvacrol (Milos et al. 2001).<br />
From <strong>the</strong> leaching (heterogeneity test) results <strong>and</strong> catalyst activity tests for<br />
<strong>carvacrol</strong> conversion reactions, Cr (salpn)-NaY was found to be relatively more<br />
efficient <strong>and</strong> stable catalyst than <strong>the</strong> o<strong>the</strong>rs. So <strong>thymol</strong> oxidation <strong>and</strong> essential oil<br />
oxidation reactions were carried out with Cr (salpn)-NaY catalyst.<br />
The conversion <strong>of</strong> <strong>carvacrol</strong> <strong>and</strong> <strong>thymol</strong> values was in <strong>the</strong> 35-39% range. Their<br />
conversion vs time pr<strong>of</strong>iles given in Figure 7.15 were very similar because <strong>of</strong><br />
similarities between <strong>the</strong>ir structures. Oxidation <strong>of</strong> <strong>carvacrol</strong> <strong>and</strong> <strong>thymol</strong> provided mainly<br />
mixture <strong>of</strong> TQ, THQ <strong>and</strong> BQ with a 31.2%, 34.5% TQ yield respectively. The yields <strong>of</strong><br />
<strong>thymol</strong> <strong>and</strong> <strong>carvacrol</strong> were very close to each o<strong>the</strong>r.<br />
In literature, TQ was produced only in small amount as a result <strong>of</strong> <strong>carvacrol</strong> <strong>and</strong><br />
<strong>thymol</strong> oxidation reactions by using different type <strong>of</strong> catalyst (Santos et al. 2003).<br />
However in our study, a relatively higher TQ formation was yielded for both <strong>thymol</strong><br />
<strong>and</strong> <strong>carvacrol</strong> oxidation reactions.<br />
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