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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Corrole Synthesis and Catalytic Applications Toward Cobalt(III)-Catalyzed Epoxidation, N-H Insertion, and Cyclopropanation

Kim, 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.
2

The development of FT-Raman techniques to quantify the hydrolysis of Cobalt (III) nitrophenylphosphate complexes using multivariate data analysis

Tshabalala, 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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