the production of thymoquinone from thymol and carvacrol

LIST OF FIGURES
Figure Page
Figure 2.1. Framework structure of zeolite Y ............................................................................. 5
Figure 2.2. Strategies for heterogenization of metal centre (M) (a) Framework
substituted (b) Grafted (c) Tethered (d) Ship in a bottle............................................ 8
Figure 3.1. Position of transition metals in the periodic table...................................................... 11
Figure 3.2. Typical monodentate ligand....................................................................................... 16
Figure 3.3. Bidentate ligand, ethylenediamine ............................................................................ 16
Figure 3.4. Typical polydentate ligands ...................................................................................... 17
Figure 3.5. (a) Shiff’s Base ligand (b) Phthalocyanine (c) Porphyrin................................18
Figure 4.1. Flexible ligand method: (a) diffusion of flexible ligand (b) formation and
encapsulation of complex in zeolite Y supercage...................................................... 20
Figure 4.2. Structure of H2salpn ................................................................................................ 20
Figure 5.1. Isoprene structure ................................................................................................ 24
Figure 5.2. Proposed possible oxidation mechanism with hydrogen peroxide............................ 30
Figure 5.3. Oxidation of carvacrol with hydrogen peroxide by using metal
complex...................................................................................................................... 31
Figure 7.1. Scanning electron micrographs of NaY (A) and Cr(salpn)-NaY (B)
Bi(salpn)-NaY (C) and Fe(salpn)-NaY (D), Ni(salpn)-NaY (E) and
Zn(salpn)-NaY (F) ................................................................................................ 39
Figure 7.2. XRD patterns of NaY zeolite (a), ligand (H2 salpn) (b), BiNaY, Bi (salpn)-
NaY (c), Ni NaY, Ni (salpn)-NaY (d), Zn NaY, Zn (salpn)-NaY (e), Cr
NaY, Cr (salpn)-NaY (f), Fe NaY, Fe (salpn)-NaY (g)............................................. 41
Figure 7.3. IR spectra of zeolite NaY, CrNaY, ZnNaY, FeNaY, NiNaY, BiNaY....................... 43
Figure 7.4. IR spectra of Cr(salpn)-NaY, Cr (salpn) (a), Bi(salpn)-NaY, Bi(salpn) (b),
Fe (salpn)-NaY, Fe(salpn) (c), Ni(salpn)-NaY, Ni(salpn) (d), Zn (salpn)-
NaY, Zn (salpn) (f) ................................................................................................ 44
Figure 7.5. IR spectra ligand (H2 salpn) ....................................................................................... 46
Figure 7.6. DSC analysis of H2 (salpn) (L) ligand ................................................................ 48
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