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Corrole Synthesis and Catalytic Applications Toward Cobalt(III)-Catalyzed Epoxidation, N-H Insertion, and CyclopropanationKim, Chung Sik 31 December 2010 (has links)
A variety of bromocorroles, useful precusors for Pd-based cross coupling, were sucessfully synthesized in moderate to good yields. Chiral corroles were also synthesized through use of chiral amides in the aforementioned cross coupling reactions. Cobalt complexes bearing π-acceptor (CNtBu) and σ-donor (PPh3) ligands were also prepared in excellent yields. In this dissertation, cobalt (III) corrole complexes were applied to three different reaction areas: epoxidation, N-H insertion, and cyclopropanation. Cobalt(III) corroles were found to be efficient catalysts for epoxidation reactions. The epoxidation reactions can be carried out using ethyl phenyldiazoacetate, an acceptor/donor diazo compound, as a carbenoid precusor.The reaction provided highly diastereoselective epoxides. In addition to epoxidation, N-H insertion reactions using cobalt(III) corroles as catalysts smoothly produced the desired products with diverse diazo reagents. The reactions were screened using ethyl phenyldiazoacetate with a selection of anilines and amides. In order to investigate non-ylide intermediate based metal-mediated catalytic reactions, cyclopropanation was conducted using cobalt (III) corroles as catalysts, producing the desired cyclopropyl nitroesters in high yields and with excellent diastereoselectivity under a concerted mechanism. Asymmetric cyclopropanation reactions were carried out using chiral cobalt(III) corrole complexes to generate the enatiomerically pure desired cyclopropanes in moderate yields.
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The development of FT-Raman techniques to quantify the hydrolysis of Cobalt (III) nitrophenylphosphate complexes using multivariate data analysisTshabalala, Oupa Samuel 03 1900 (has links)
The FT-Raman techniques were developed to quantify reactions that
follow on mixing aqueous solutions of bis-(1,3-diaminopropane)diaquacobalt(
III) ion ([Co(tn)2(0H)(H20)]2+) and p-nitrophenylphosphate
(PNPP).
For the development and validation of the kinetic modelling
technique, the well-studied inversion of sucrose was utilized. Rate
constants and concentrations could be estimated using calibration
solutions and modelling methods. It was found that the results
obtained are comparable to literature values. Hence this technique
could be further used for the [Co(tn)2(0H)(H20)]2+ assisted
hydrolysis of PNPP.
It was found that rate constants where the pH is maintained at 7.30
give results which differ from those where the pH is started at 7.30
and allowed to change during the reaction. The average rate
constant for 2:1 ([Co(tn)2(0H)(H20)]2+:PNPP reactions was found to
be approximately 3 x 104 times the unassisted PNPP hydrolysis rate. / Chemistry / M. Sc. (Chemistry)
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