Synthesis of 2-iodomethylene-2,3-dihydro-1,4-oxazepine derivatives

Çakal, Deniz
In this thesis, platinum nanoparticles were prepared by using PtCl4 as a starting material, sodium borohydride (Group I), hydrazine (Group II) and formaldehyde (Group III) as reducing agents and hexylamine (Group -a), N-methylhexylamine (Group -b), N,N-dimethylhexylamine (Group -c) as surfactants (the last two surfactants were used for the first time). These platinum nanoparticles were dispersed on Carbon XC-72 to be utilized as catalyst for methanol oxidation reaction which can be used in direct methanol fuel cells. The characterization, electrochemical properties and performance of catalysts were defined by using inductively coupled plasma spectroscopy (ICP), cyclic voltametry (CV), chronoamperometry (CA), X-ray diffraction (XRD), X-photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM), BET surface area analysis and fourier transform infrared spectroscopy (FTIR). XRD and TEM results indicated that platinum crystallizes in face-centered cubic (fcc) structure with a size of ~5 nm. In addition to these small particles, agglomerated particles were also observed in different size, shape and density. In Group I, cubic platinum nanoparticles come together to form large particles with a size of 20 - 200 nm. In Group II, agglomerated particles were appeared to be dense, large and spherical lumps with a size of 50 - 200 nm. In Group III, the agglomerated particles were also formed in spherical shape but not as much dense and large (50 - 150 nm) as in Group II. XPS results revealed that there are two different oxidation states of platinum in each catalyst. These are Pt(0) and Pt(IV) and their percentages changes between 65 - 73 and 35 - 27, respectively. XPS data also showed the existence of two kinds of oxygen, HOads and H2Oads, with a ratio of 85:15, 90:10 and 80:20 for Group I, II and III, respectively. BET analyses indicated that the surface area of catalysts depends on reducing agent not surfactant. It was 30 - 35 m2/g, 4 - 9 m2/g and 20 - 30 m2/g for Group I, II and III, respectively. CV records demonstrated that the order of catalysts performance was Group II < Group I < Group III. Within all catalysts, Catalyst IIIb exhibited the highest performance (258 mA/mg Pt) towards methanol oxidation reaction and provided 3.5 times greater performance than the commercial E-TEK Pt catalyst. All these data indicated that the performance of these catalysts depends on: a) active surface area, b) HOads/ H2Oads ratio, and c) morphology of the catalysts.


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Çokangın, Aysu; Gökağaç Arslan, Gülsün; Department of Chemistry (2015)
In this thesis, carbon supported platinum nanoparticle catalysts were synthesized by using PtCl4 as precursor, sodium borohydride (Cat I), hydrazinum hydroxide (Cat II) and formaldehyde (Cat III) as reducing agent and 1-heptanamine (a), Nmethylheptanamine (b) and N,N-dimethylheptanamine (c) as surfactants for methanol oxidation reaction. Their physical and electrochemical properties were determined by inductively coupled plasma spectroscopy (ICP), cyclic voltammetry (CV), and characterization methods of X-r...
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Kalyoncu, Sevda; Gökağaç Arslan, Gülsün; Department of Chemistry (2015)
In this thesis, carbon supported platinum catalysts were synthesized to investigate the effect of reducing agent and surfactant on the performance of catalyst towards methanol oxidation reaction. For this purpose, the catalysts were prepared by using PtCl4 as a starting material, propylamine (a) and dipropylamine (b) as surfactant, and sodium borohydride (catalyst I) and formaldehyde (catalyst II) as reducing agent. The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron ...
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The enantioselective synthesis of 2-indolyl-1-nitro derivatives and BODIPY dyes in the presence of chiral bifunctional squaramide organocatalysts
Dündar, Esra; Tanyeli, Cihangir; Department of Chemistry (2022-8)
In our research group, chiral bifunctional squaramides with different basic units have been synthesized and evaluated in various asymmetric reactions. To test the catalytic activity of organocatalysts, Friedel-Crafts alkylation of indoles with nitroolefins was selected as a model reaction in the first part of the study. 19 different 2-indolyl-1-nitro derivatives were synthesized with up to >99% ee in the presence of sterically encumbered tert-butyl substituted squaramide/quinine. Besides, 2-adamantyl squara...
Citation Formats
D. Çakal, “Synthesis of 2-iodomethylene-2,3-dihydro-1,4-oxazepine derivatives,” M.S. - Master of Science, Middle East Technical University, 2014.