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Selective carbon-carbon bond activation of ethers by rhodium porphyrins. / CUHK electronic theses & dissertations collection

*Please refer to dissertation for diagrams. / Part 1 describes the selective C(alpha)-(beta) bonds cleavage of a series of aliphatic ethers (RCH2OCH2R: R = Et, Pr, Bu, iBu and pentyl) by RhII(tmp) using PPh3 as the promoting ligand to give Rh(tmp)-alkyls bearing the C(beta)-substituent in 13-40% yields at 24°C. The rate and the yields of Rh(tmp)-alkyls decreased with increasing steric hindrance of ethers. Addition of bases such as KOtBu, CsOH.H2O and KOH as well as H2O further promoted the product yields of the reactions with n-butyl ether to 56-62%. The reaction between RhII(tmp) and the cyclic ether, oxepane, at 24°C for 1 day gave Rh(tmp)(CH2)5OCHO in 17% yield suggesting that Rh(tmp)OH is the key intermediate in the C-C cleavage step and presumably generated via the PPh3-, H2O-, and OH --assisted disproportionation of RhII(tmp).* / Secondly, the reductive dehydrogenation of Rh(tmp)H to RhII(tmp) was also observed. Rh(tmp)H reacted with KOH in benzene-d6 at 100°C for 1 hour to give RhII(tmp) in 30% yield. [Rh I(tmp)]- is proposed to form initially via the deprotonation of Rh(tmp)H with KOH and then reacts with the unreacted Rh(tmp)H to give Rh II(tmp) via electron transfer. Thirdly, the hydroxide-induced disproportionation of RhII(tmp) to RhIII(tmp)OH and [Rh I(tmp)]- has also been proposed.* / The objective of this thesis focuses on studies of selective, base-promoted aliphatic carbon(alpha)-carbon(beta) bond activation (CCA) of ethers with rhodium(II) and rhodium(III) meso-tetramesitylporphyrin complexes (Rh II(tmp) and Rh(tmp)I). The roles of potassium hydroxide in promoting the interconversions of rhodium porphyrin species (RhII(tmp), Rh(tmp)I, Rh(tmp)OH and Rh(tmp)H) will also be discussed. / Lai, Tsz Ho. / Adviser: Kin Shing Chan. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 161-172). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Identiferoai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344540
Date January 2010
ContributorsLai, Tsz Ho., Chinese University of Hong Kong Graduate School. Division of Chemistry.
Source SetsThe Chinese University of Hong Kong
LanguageEnglish, Chinese
Detected LanguageEnglish
TypeText, theses
Formatelectronic resource, microform, microfiche, 1 online resource (xii, 196 leaves : ill.)
RightsUse of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

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