Masters Degrees (Chemistry)

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Browsing Masters Degrees (Chemistry) by Author "Buitendach, Blenerhassitt Edward"

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    Synthesis of novel polymer-bound morpholine-N-oxides as possible oxidants in alkene oxidation
    (University of the Free State, 2008-03) Buitendach, Blenerhassitt Edward; Swarts, J. C.; Bezuidenhoudt, B. C. B.
    English: In this dissertation is reported the syntheses and characterisation of polysuccinimide- and polyepichlorohydrin-bound morpholine-N-oxide as possible polymeric oxidants. The use of 1H NMR spectroscopy to determine polymer chain length and degree of fuctionalisation is described in detail. The synthesised polymers were used as potential oxidants in catalytic oxidation of alkenes. However, none of the preliminary trials on the epoxidation and dihydroxylation of trans-stilbene were successful. Two metal-containing phthalocyanines; one coordinated to Mn(III), the other to Zn(II), were synthesized by metal insertion into the metal-free non-peripheral octa substituted phthalocyanine (2HPc-(C13H27)8). The initial complex, 2HPc-(C13H27)8, was synthesized by tetramerization of 3,6-tridecylphthalonitrile, which was prepared by a three-step synthesis from thiophene. Characterization of the phthalocyanines included electrochemical and thermal analysis. The cyclic voltammograms of the 2H and Zn phthalocyanines showed two ringbased oxidations (0.116 V; 0.487 V and 0.044 V; 0.558V respectively) as well as two ringbased reductions (-1.791 V; -1.456 V and -2.054 V; -1.663 V respectively), vs Fc/Fc+ at 100 mV/s. The Mn derivative showed two ring-based oxidations (0.373 V and 0.864 V) while only one ring-based reduction was observed (-1.732 V). The Mn(II) oxidation was observed at 0.641 V while Mn(III) reductions was observed at -0.742 V and -0.660 V (for Cl- and CH3Oaxial ligands) giving large Ep values of 1.566 V and 1.484 V.The newly synthesized tridecyl-substituted metal-free and zinc phthalocyanines exhibited liquid crystalline mesophase behavior when subjected to differential scanning calorimetric studies of between 40 oC – 120 oC and 40 oC – 280 oC respectively, giving mesophase temperature ranges of 12.4 oC and 83.0 oC respectively. The manganese phthalocyanine, xii however, did not show any liquid crystal behavior. The manganese tridecyl-substituted phthalocyanine was used as catalyst in the molecular oxygen based epoxidation of transstilbene and gave low yields of the desired epoxide, trans-stilbene oxide. Epoxidation of trans-stilbene using N-methylmorpholine-N-oxide as oxidant and Mn(III)salen as co-catalyst gave trans-stilbene oxide in moderate yields.