the production of thymoquinone from thymol and carvacrol

washed with 10 ml cold methanol and dried. Finally, the ligand was recrystallized from
methanol to give pure product. The melting point of ligand was found by differential
scanning calorimetric analysis (DSC). DSC analysis was conducted using Shimadzu
DSC50 types of instrument. Run was carried out up to 600 o C at 10 ºC/min heating rate
and nitrogen flow rate with 3 mg of sample.
6.2.1.2. Preparation of Metal Exchanged Zeolite Y
NaY-zeolite (5 g) was suspended in 300 ml deionized water containing 0.01 M
of metal (Cr(III), Fe(III), Bi(III), Ni(II), Zn(II)) nitrates. The mixture was heated to 60
ºC while stirring for 24 hours. The solid was filtrated, washed with hot distilled water
till the filtrate was free from any metal ion content and then dried for 24 hours at 90 ºC
in air.
6.2.1.3. Preparation of Encapsulated Complexes
The encapsulated metal complex was prepared by general flexible ligand
method. A total of 5g metal exchanged Y zeolite and 10 g of ligand were mixed in
round bottom flask. The mixture was heated at 100 ºC overnight (19 hours) in an oil
bath with stirring. The ligand was melted at that temperature and acted as a solvent as
well as a reactant. The resulting material was taken out and soxhlet extracted with
methanol till the complex was free from unreacted excess ligand (at least 62 hours). The
uncomplexed metal ions present in the zeolite were removed by exchanging them with
0.01 M aqueous NaCl solution for 5 hours. The resulting solid then was washed with
hot distilled water till no precipitation of AgCl on reacting filtrate with AgNO3 was
observed. The colored solid was dried at 90 ºC for 24 hours.
6.2.2. Catalyst Characterization
X-ray diffraction (XRD) patterns of the samples were recorded on a Philips
X'pert Pro X-ray diffractometer with Cu K radiation. Infrared spectra in the region
400-4000 cm -1 were recorded in KBr pellets using a Shimadzu 8101 FT-IR
spectrophotometer. The metal contents in the products were determined by an
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