Synthesis of novel polymer-bound morpholine-N-oxides as possible oxidants in alkene oxidation
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Buitendach, Blenerhassitt Edward
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University of the Free State
Abstract
Showing abstract in English
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,
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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.