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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Figure 7.4 (cont.)<br />
The IR spectra <strong>of</strong> <strong>the</strong> encapsulated complexes were essentially similar to that <strong>of</strong><br />
<strong>the</strong> free complexes; this was observed <strong>from</strong> Figure 7.4. However, some IR b<strong>and</strong>s <strong>of</strong><br />
encapsulated complexes <strong>and</strong> free lig<strong>and</strong> showed some differences <strong>from</strong> each o<strong>the</strong>r. For<br />
example free lig<strong>and</strong> (H2salpn) exhibited (C=N) stretch at 1580 1/cm. In complexes,<br />
this b<strong>and</strong> shifted to lower frequency. As seen in Table 7.2, this b<strong>and</strong> appeared in <strong>the</strong><br />
range 1523-1570 1/cm. This shift was <strong>the</strong> indication <strong>of</strong> <strong>the</strong> coordination <strong>of</strong> azomethine<br />
nitrogen to <strong>the</strong> metal. Our results showed good agreement with <strong>the</strong> results reported in<br />
<strong>the</strong> literature earlier (Maurya et al. 2002a; Maurya et al. 2003). According to <strong>the</strong> FTIR<br />
results, <strong>the</strong>re was no significant expansion <strong>of</strong> <strong>the</strong> zeolite cavities, dealumination or<br />
structural changes during <strong>the</strong> encapsulation process. IR spectra <strong>of</strong> NaY zeolite, metal-<br />
exchanged zeolites <strong>and</strong> catalysts were shown in Figure 7.3. This indicated that, <strong>the</strong><br />
structure <strong>of</strong> metal complexes fitted nicely within <strong>the</strong> cavity <strong>of</strong> <strong>the</strong> zeolite. The presence<br />
<strong>of</strong> several b<strong>and</strong>s <strong>of</strong> low intensity in 2700–2900 1/cm regions indicated <strong>the</strong> existence <strong>of</strong><br />
ethylene group <strong>of</strong> <strong>the</strong> amine residue <strong>of</strong> <strong>the</strong> lig<strong>and</strong>.<br />
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