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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

Kinetics and mechanisms of methoxide substitution and electroreduction of hexachlorobenzene

Sidhu, Jeswant K., University of Western Sydney, Faculty of Informatics, Science and Technology January 2000 (has links)
Hexachlorobenzene (HCB) is a pollutant, and there is an urgent need to degrade it. Two methods of degrading HCB to ethers are nucleophilic substitution and electroreduction, chosen for their viability and safety. The kinetics of substitution of HCB by potassium hydroxide and methanol were examined. The substitution of HCB by methoxide produced 1,2,3,5-tetrachloro-4.6-dimethoxybenzene (1,2,3,5-TCDMB) as the major substitution product, and side reactions produced extra chloride due to other substitution products. Thus, the proposed reaction mechanism is complicated due to the formation of ethers and phenols due to consecutive and parallel reactions. The substitution products of HCB were uncatalytically and catalytically electroreduced. Products with increasingly more methoxy substituents had lower electron affinities and increasing positive free energies. Catalysed electroreduction was more effective than uncatalysed electroreduction in dechlorinating the HCB substitution products to aromatic ethers. The most effective organic catalysts were those that possessed the lowest electron affinity as reflected in the reduction potential. A combination of nucleophilic substitution and electroreduction of HCB and its substitution products produced mono-, di- and trimethoxide chloroaromatic ethers and phenols. These products, particularly the ethers, may have future applications as fragrance ingredients / Doctor of Philosophy (PhD)

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