Return to search

Part I, base-promoted aryl-bromine bond cleavage by cobalt(ii) porphyrins. / Base-promoted aryl-bromine bond cleavage by cobalt(ii) porphyrins / Part II, catalytic hydrodehalogenation of aryl bromides by cobalt(ii) porphyrin in alkaline conditions / Catalytic hydrodehalogenation of aryl bromides by cobalt(ii) porphyrin in alkaline conditions

本論文主要研究了鹼性添加劑促進二價鈷卟啉絡合物(Co{U+1D35}{U+1D35}(por))在苯溶劑中與溴代苯及其衍生物(ArX)的反應及鹼性條件下,該絡合物催化溴代苯及其衍生物的脫鹵反應。 / 第一部分主要介紹了在KOH和{U+1D57}BuOH存在下,Co{U+1D35}{U+1D35}(por)斷裂碳-溴鍵(Ar-Br)形成各種三價鈷卟啉芳基絡合物(Co{U+1D35}{U+1D35}{U+1D35}(por)Ar)(eq. 1)。 / 機理研究顯示,Co{U+1D35}{U+1D35}(por)首先從ArBr中得到Br·形成芳基自由基(Ar·)及Co{U+1D35}{U+1D35}{U+1D35}(por)Br (Scheme 1, i). Ar 與另一個Co{U+1D35}{U+1D35}(por)反應得到Co{U+1D35}{U+1D35}{U+1D35}(por)Ar (Scheme 1, ii)。在鹼性條件中,Co{U+1D35}{U+1D35}{U+1D35}(por)Br 最終形成CoII(por)從而繼續反應 (Scheme 1, iii-iv)。 / 第二部份主要介紹了在200 ºC時, 鹼性條件下Co{U+1D35}{U+1D35}(por)催化鹵代苯及其衍生物脫鹵形成對應芳烴的反應 (eq. 2)。 該反應在四氫呋喃(THF)及異丙醇 ({U+2071}PrOH) 中都可以進行。 / 機理研究顯示, Co{U+1D35}{U+1D35}(ttp) 首先與ArBr反應得到Ar· 和Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br (Scheme 2, i)。 Ar 從溶劑(THF 或者 {U+2071}PrOH)得到一個氫原子從而形成芳烴 (ArH) (Scheme 2, ii)。 Ar 也可以與另一個Co{U+1D35}{U+1D35}(ttp) 反應得到Co{U+1D35}{U+1D35}{U+1D35}(ttp)Ar。 在鹼性條件下, Co{U+1D35}{U+1D35}{U+1D35}(ttp)Ar水解形成ArH 和 Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH (Scheme 2, iii)。 Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br 與KOH進行取代反應得到Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH, 并最終形成催化劑Co{U+1D35}{U+1D35}(ttp) (Scheme 1, iii-iv)。所以, 溶劑 (THF 或者 {U+2071}PrOH)及H₂O 都可以作為Co{U+1D35}{U+1D35}(ttp) 催化鹵代苯脫鹵形成芳烴的氫的來源。 / This thesis focuses on (1) the base-promoted aryl bromine bond (Ar-Br) cleavages by cobalt(II) porphyrins and (2) catalytic hydrodehalogenation of aryl bromides by cobalt(II) porphyrin in alkaline conditions. / Part I describes the aryl bromine bond cleavage with cobalt(II) porphyrin (Co{U+1D35}{U+1D35}(por)) in the presence of KOH and {U+1D57}BuOH in benzene at 150ºC to give cobalt(III) porphyrin aryls (Co{U+1D35}{U+1D35}{U+1D35}(por)Ar) (eq. 1). / [With images] / Mechanistic studies suggest that CoII(por) first abstracts the bromine atom from the aryl bromide to form aryl radical (Ar) and Co{U+1D35}{U+1D35}{U+1D35}(por)Br (Scheme 1, i). Ar· further reacts with Co{U+1D35}{U+1D35}(por) to generate Co{U+1D35}{U+1D35}{U+1D35}(por)Ar (Scheme 1, ii). Co{U+1D35}{U+1D35}{U+1D35}(por)Br undergoes ligand substitution with KOH to form Co{U+1D35}{U+1D35}{U+1D35}(por)OH, which quickly gives Co{U+1D35}{U+1D35}(por) and H₂O₂ (Scheme 1, iii). H₂O₂ undergoes base-promoted decomposition to form H₂O and O₂ (Scheme 1, iv). / [With images] / Scheme 1 Reaction Mechanism of Base-promoted Ar-Br Cleavage with Co{U+1D35}{U+1D35}(por) / Part II describes the catalytic hydrodehalogenation of aryl bromides by Co{U+1D35}{U+1D35}(ttp) at 200 ºC in alkaline conditions to generate arenes (eq. 2). The reaction can occur in both THF and {U+2071}PrOH. / [With images] / Mechanistic studies suggest that Co{U+1D35}{U+1D35}(ttp) also first abstracts the bromine atom from the aryl bromide in the presence of KOH to form Ar· and Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br (Scheme 2, i). Ar· can abstract a hydrogen atom from the solvent (THF or {U+2071}PrOH) to form arenes (Scheme 2, ii). Ar also could be trapped by Co{U+1D35}{U+1D35}(ttp) to give Co{U+1D35}{U+1D35}{U+1D35}(ttp)Ar, which undergoes hydrolysis in the presence of OH⁻ to the arene (ArH) and Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH (Scheme 2, iii). Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br gives Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH by ligand substitution with KOH and Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH regenerates the catalyst Co{U+1D35}{U+1D35}(ttp) (Scheme 1, iii-iv). The solvent (THF or {U+2071}PrOH) and H₂O are the hydrogen sources for the catalytic dehalogenation of aryl bromides by Co{U+1D35}{U+1D35}(ttp). / Scheme 2 Mechanism of Catalytic Dehalogentaion of ArBr by CoII(ttp) in Alkaline Media / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liu, Chunran. / "October 2012." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves ). / Abstracts also in Chinese. / Chapter Table of Contents --- p.i / Chapter Acknowledgements --- p.iv / Chapter Abbreviations --- p.v / Chapter Abstract --- p.vi / Chapter Part I --- The Base-promoted Aryl Bromine Bond Cleavage of Aryl Bromides by Cobalt(II) Porphyrins / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- Introduction to Porphyrins and Group 9 metalloporphyrins --- p.1 / Chapter 1.1.1 --- Porphyrin Ligand --- p.1 / Chapter 1.1.2 --- Group 9 metalloporphyrins --- p.2 / Chapter 1.1.3 --- Chemistry of Group 9 Metalloporphyrin --- p.3 / Chapter 1.1.3.1 --- Chemsitry of M{U+1D35}(por) --- p.3 / Chapter 1.1.3.2 --- Chemsitry of M{U+1D35}{U+1D35}(por) --- p.4 / Chapter 1.1.3.3 --- Chemsitry of M{U+1D35}{U+1D35}{U+1D35}{U+1D35}(por) --- p.4 / Chapter 1.1.3.4 --- Chemsitry of M{U+1D35}{U+1D35}{U+1D35}{U+1D35}(por)OH --- p.6 / Chapter 1.2 --- Physical Properties of Aryl Halides --- p.9 / Chapter 1.3 --- Synthesis of Metalloporphyrin Aryl --- p.10 / Chapter 1.4 --- Modes of Reactivity of Aryl Carbon-Halogen Bond Cleavage by Transition Metal Complexes --- p.11 / Chapter 1.4.1 --- Oxidative Addition (OA) --- p.11 / Chapter 1.4.2 --- Nucleophilic Aromatic Substitution (SNA) --- p.14 / Chapter 1.4.3 --- Halogen Atom Transfer (HXA) --- p.14 / Chapter 1.4.4 --- Radical ipso-Substitution --- p.15 / Chapter 1.5 --- Scope of Part I --- p.16 / Chapter Chapter 2 --- Base-promoted Aryl Bromine Bond Cleavage of Aryl Bromides by Cobalt(II) Porphyrins / Chapter 2.1 --- Introduction --- p.17 / Chapter 2.2 --- Objectives of the Work --- p.18 / Chapter 2.3 --- Preparation of Starting Materials --- p.18 / Chapter 2.3.1 --- Synthesis of Porphyrin --- p.18 / Chapter 2.3.2 --- Synthesis of Cobalt(II) Porphyrin --- p.18 / Chapter 2.3.3 --- Synthesis of Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br --- p.19 / Chapter 2.4 --- Discovery of Ph-Br Bond Cleavage by Co{U+1D35}{U+1D35}(ttp) with KOH --- p.19 / Chapter 2.5 --- Optimization of Reaction Conditions --- p.20 / Chapter 2.5.1 --- {U+1D57}BuOH Effect --- p.20 / Chapter 2.5.2 --- Solvent Effect --- p.21 / Chapter 2.5.3 --- Temperature Effect --- p.21 / Chapter 2.5.4 --- Base Loading Effect --- p.22 / Chapter 2.6 --- Summary of Optimization of the Base-promoted Ph-Br Bond Cleavage by Co{U+1D35}{U+1D35}(ttp) --- p.22 / Chapter 2.7 --- Porphyrin Ligand Effect --- p.23 / Chapter 2.8 --- Substrate Scope of Aryl Bromides --- p.24 / Chapter 2.9 --- Mechanistic Studies --- p.25 / Chapter 2.9.1 --- Possible Pathways of Ar-Br Bond Cleavage --- p.25 / Chapter 2.9.1.1 --- Oxidative Addition (OA) --- p.26 / Chapter 2.9.1.2 --- Nucleophilic Aromatic Substitution (SNA) --- p.27 / Chapter 2.9.1.3 --- Radical ipso-Substitution --- p.28 / Chapter 2.9.1.4 --- Halogen Atom Transfer (HXA) --- p.28 / Chapter 2.9.2 --- Electronic Effect of 4-Substituted ArBr by Hammett Plot --- p.29 / Chapter 2.9.3 --- Proposed Mechanism --- p.32 / Chapter 2.9.4 --- Evidence for Halogen Atom Transfer --- p.33 / Chapter 2.10 --- Conclusion --- p.35 / Chapter Chapter 3 --- Experimental Section --- p.36 / Reference --- p.53 / Chapter Part II --- Catalytic Hydrodehalogenation of Aryl Bromides by Cobalt(II) Porphyrin in Alkaline Conditions / Chapter Chapter 4 --- General Introduction --- p.58 / Chapter 4.1 --- Introduction --- p.58 / Chapter 4.1.1 --- Properties of Halogenated Aromatic Compounds --- p.58 / Chapter 4.1.2 --- Reactivity of Aryl Carbon-Halogen Bond --- p.59 / Chapter 4.2 --- Hydrodehalogenation of Aryl Halides by Transiton Metal Complexes --- p.59 / Chapter 4.2.1 --- Molecular Hydrogen (H₂) --- p.60 / Chapter 4.2.2 --- Alcohols and Metal Alkoxides --- p.61 / Chapter 4.2.3 --- Dimethyformamide (DMF) --- p.64 / Chapter 4.2.4 --- Hydrazine (NH₂-NH₂) --- p.65 / Chapter 4.2.5 --- Metal Hydrides --- p.65 / Chapter 4.2.6 --- Alkyl Grignard Reagents --- p.67 / Chapter 4.2.7 --- Formic Acid and Its Salts --- p.67 / Chapter 4.3 --- Common Reducing Agents --- p.69 / Chapter 4.3 --- Scope of Part II --- p.69 / Chapter Chapter 5 --- Catalytic Hydrodehalogenation of Aryl Bromides by Cobalt(II) Porphyrin in Alkaline Conditions / Chapter 5.1 --- Introduction --- p.70 / Chapter 5.2 --- Objectives of the Work --- p.71 / Chapter 5.3 --- Optimization of Reaction Conditions --- p.71 / Chapter 5.3.1 --- Solvent Effect --- p.71 / Chapter 5.3.2 --- Temperature Effect --- p.72 / Chapter 5.3.3 --- Base Loading Effect --- p.73 / Chapter 5.3.4 --- Porphyrin Loading Effect --- p.73 / Chapter 5.3.5 --- Atmosphere Effect --- p.74 / Chapter 5.4 --- Summary of Optimization of Hydrodehalogention of Aryl Bromides by Co{U+1D35}{U+1D35}(ttp) --- p.74 / Chapter 5.5 --- Substrate Scope of Aryl Bromides --- p.75 / Chapter 5.5.1 --- THF as the Solvent --- p.75 / Chapter 5.5.2 --- {U+2071}PrOH as the Solvent --- p.76 / Chapter 5.6 --- Catalytic Reactivity of Co{U+1D35}{U+1D35}(ttp) as the Catalyst --- p.77 / Chapter 5.7 --- Mechanistic Studies --- p.78 / Chapter 5.7.1 --- Proposed Mechanism of Hydrodehalogenation of Aryl Bromides by Co{U+1D35}{U+1D35}(ttp) --- p.78 / Chapter 5.7.2 --- Hydrogen Source Investigation --- p.80 / Chapter 5.8 --- Conclusion --- p.83 / Chapter Chapter 6 --- Experimental Section --- p.84 / Reference --- p.92 / Chapter Appendix --- Appendix I --- p.101 / Appendix II --- p.112 / Appendix III --- p.118

Identiferoai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_328692
Date January 2013
ContributorsLiu, Chunran., Chinese University of Hong Kong Graduate School. Division of Chemistry.
Source SetsThe Chinese University of Hong Kong
LanguageEnglish, Chinese
Detected LanguageEnglish
TypeText, bibliography
Formatelectronic resource]Part II, catalytic hydrodehalogenation of aryl bromides by cobalt(ii) porphyrin in alkaline condition, electronic resource, remote, 1 online resource (viii, 119 leaves) : ill. (some col.)
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/)

Page generated in 0.0028 seconds