Responsive image
博碩士論文 etd-0806106-234831 詳細資訊
Title page for etd-0806106-234831
論文名稱
Title
銀(111)單晶表面碳氫基團之碳-碳鍵形成反應:立體能障、電子誘導效應與碳原子混成軌域對速率的影響
Carbon-Carbon Bond Forming Reactions of Metal-Bonded Hydrocarbon Groups on Ag(111): Steric, Electronic, and Carbon Hybridization Effects on the Coupling Rates
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
59
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2006-07-18
繳交日期
Date of Submission
2006-08-06
關鍵字
Keywords
程溫脫附/反應、β-脫氫反應、銀(111)、混成軌域、電子誘導效應、立體效應、烷基取代、超高真空系統、自偶合反應、1-3 立體排斥作用力
Ag(111), alkyl substitution, steric effects, β-H elimination, homo-coupling, UHV, inductive electronic effects, 1-3 repulsive steric interactions, TPD/R, orbital hybridization
統計
Statistics
本論文已被瀏覽 5720 次,被下載 1711
The thesis/dissertation has been browsed 5720 times, has been downloaded 1711 times.
中文摘要
由於銀與氫親和力很低以及銀-氫鍵較其它金屬-碳鍵為弱,導致碳氫自由基在銀表面傾向自偶合(homo-coupling)形成碳-碳鍵而不容易進行碳-氫鍵裂斷反應。本文旨在於超高真空條件下,使用程溫脫附/反應 (TPD/R) 來研究烷基取代以及α碳(和金屬表面或鹵素鍵結的碳)之混成軌域對於碳氫化合物自偶合反應速率的影響。基於這兩種不同的研究目標,所使用的鹵化前驅物也分為兩大部分:一部份為α碳(皆為sp3)具有氫的鹵化烷類分子;另一部份則是 α碳(有各種不同的混成軌域)上不具有氫的鹵化碳氫化合物,再進一步利用碳-溴或碳-碘鍵容易熱烈解的特性在Ag(111)上產生相對應的吸附基團。在烷基取代的研究中,我們有系統的改變α碳(sp3)上烷基取代的大小以及數目並觀察各個物種在Ag(111)上其自偶合產物脫附的溫度。結果顯示,3-戊烷基的產物脫附溫度比乙烷基高了約70 K,這表示在烷基取代效應中立體障礙的影響大於電子誘導效應,而由立體障礙所導致的反應活化能升高和以"geminal repulsion"的大小所預測的趨勢是符合的。另一方面,在針對α碳上不同混成軌域對自偶合反應速率影響的實驗中,α碳為sp 混成的物種(1-丙炔碘(CH3C≡CI)以及三甲基矽基乙炔碘((CH3)3SiC≡CI))被觀察到有特別高的產物脫附溫度約在460 K左右,在自偶合反應的過渡態中有牽涉到銀-碳鍵斷裂以及碳-碳鍵形成,我們認為由於Cα(sp)物種具有較強的銀-碳鍵以及較高的混成軌域方向性因而造成較高的活化能。同時從實驗的結果中也可以發現自偶合反應速率快慢和α碳的混成有著以下順序: sp3 > sp2 > sp。最後在異丁烷基(isobutyl)的實驗中,並沒有如預期的有自偶合反應發生,取而代之的是在銀表面上鮮少發生的β-hydide elimination,我們推測這是由於異丁烷基擁有在所有碳氫化合物中最多的九個β氫,而使得β-H elimination 反應發生的可能性提高許多。
Abstract
The alkyl substitution effects and the hybridization effects on the rate of coupling of adsorbed hydrocarbon groups on Ag(111) have been investigated under ultrahigh vacuum by temperature programmed reaction/desorption (TPR/D). For these two different issues, two types of halide precursors were used. One is to form adsorbed fragments bearing Cα(sp3) and Cα-H, the other is to yield adsorbed fragments with different hybridized α-carbons without Cα-H. The desired hydrocarbon groups were generated on Ag(111) by the thermal dissociation of the C-X (X = I or Br) bond in the corresponding halogenated compounds. Substitution of alkyl for hydrogen in the adsorbed alkyl groups systematically raises the coupling temperature. For example, 3-pentyl groups homo-couple at temperatures ~ 70 K higher than the ethyl homo-coupling reaction. The concept of “geminal repulsion” can account for our experimental results while the size and the number of the alkyl substitution groups increase. Different hybridized Cα (metal-bonded carbon) species cause various angle strain energies in the cyclic transition state for the coupling reaction. The Cα(sp) species (CH3C≡C(ad) and (CH3)3SiC≡C(ad)) have rather high coupling temperatures (~ 460 K) due to the unidirectional sp orbital and the stronger Ag-C(sp) bond in the transition state. The relative rates for homo-coupling as a function of the hybridization of the metal-bound carbon follow the trend sp3 > sp2 > sp on the Ag(111) surface. Lastly, we found that the isobutyl groups undergo a β-hydride elimination instead of homo-coupling on the Ag(111) surface. It may be due to that isobutyl groups have a total of nine β-hydogens among all the hydrocarbon groups, which makes this rare reaction pathway possibly occur on Ag(111).
目次 Table of Contents
Chapter 1

Introduction
……………………………………………… 1

Chapter 2

Experimental
……………………………………………… 5

Chapter 3 Results

3.1 The Surface Chemistry of iodoethane, 1-iodopropane, and 2-iodopropane on Ag(111)
……………………………………………… 8

3.2 The Surface Chemistry of 2-iodobutane on Ag(111)
……………………………………………… 14

3.3 The Surface Chemistry of 3-bromopentane on Ag(111)
……………………………………………… 17

3.4 The Surface Chemistry of Propynyl Iodide ( Cα(sp) ) on Ag(111)
……………………………………………… 20

3.5 The Surface Chemistry of 1-iodo-2-(trimethylsilyl) acetylene ( Cα(sp) ) on Ag(111)
……………………………………………… 23

3.6 The Surface Chemistry of Phenyl Iodide ( Cα(sp2) ) on Ag(111)
……………………………………………… 25

3.7 The Surface Chemistry of 2-iodo-2-methylpropane ( Cα(sp3) ) on Ag(111)
……………………………………………… 28

Chapter 4 Discussion

4.1 Steric Effect on the Transition State for Alkyl Coupling Reactions
……………………………………………… 31

4.2 Hybridization Effect on the Coupling Rate of the Adsorbed Hydrocarbon Groups
……………………………………………… 37

Chapter 5

Conclusions
……………………………………………… 41

References
……………………………………………… 43
參考文獻 References
References
(1) Boor, J. K. Zeigler-Natta Catalysis and polymerization, 3rd ed.; Academic Press: New York, 1984
(2) Anderson, R. B. The Fischer-Tropsch Synthesis; Academic Press: New York, 1984
(3) Lee, M.-S.; Bent, S. F. J. Phys. Chem. B. 1997, 101, 9195: Bonding and Thermal Reactivity in Thin a-SiC:H Films Grown by Methylsilane CVD.
(4) Nagano, T.; Hayashi T. Chem. Lett. 2005, 34, 1152: Silver- Catalyzed Alkyl-Alkyl Homo-coupling of Grinard Reagents.
(5) Zaera, F. Chem. Rev. 1995, 95, 2651: An organometallic Guide to the Chemistry of Hydrocarbon Moieties on Transition Metal Surface.
(6) Zhou, X.-L.; solymosi, F.; Blass, P. M.; Cannon, K. C.; White, J. M. Surf. Sci. 1989, 219, 294: Interactions of Methyl Halides (Cl, Br and I) with Ag(111).
(7) Zhou, X.-L.; White, J. M. Catal. Lett. 1989, 2, 375: Thermal Decomposition of C2H5I on Ag(111).
(8) Zhou, X.-L.; White, J. M. J. Phys. Chem. 1991, 95, 5575: Reactions of Iodoethane, Iodopropane, 2-Iodopropane, Chloroiodomethane Adsorbed on Silver(111).
(9) Buelow, M. T.; Zhou, G.; Gellman A. J.; Immaraporn B. Catal. Lett. 1999, 59, 9: The Transition State for Metal-Catalyzed Dehalogenation.
(10) Buelow, M. T.; Gellman A. J. J. Am. Chem. Soc. 2001, 123, 1440: The Transition State for Metal-Catalyzed Dehalogenation: C-I Bond Cleavage on Ag(111).
(11) Buelow, M. T.; Gellman A. J. J. Phys. Chem. B. 2000, 104, 3280: Inductive Substituent Effects: Metal Surface versus the Gas Phase.
(12) Paul, A.; Gellman A. J. J. Am. Chem. Soc. 1995, 117, 9056: Fluorine Substisution Effects on the Alkyl Coupling Reaction on a Ag(111) Surface.
(13) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles and Applications of Organotransition Metal Chemistry, 2nd ed.; University Science Books: Mill Valley, CA, 1987; pp 322-333.
(14) Stille, J. K. Pure Appl. Chem. 1985, 57, 1771: Palladium Catalyzed Coupling of Organotin Reagents with Organic Electrophiles.
(15) Stille, J. K. Angew. Chem., Int. Ed. Engl. 1986, 25, 508: The Palladium-Catalyzed Cross-Coupling Reactions of Organotin Reagents with Organic Electrophiles.
(16) Trost, B. M. In Comprehensive Organic Synthesis; Pergamon Press: New York, 1991; Vol. 3, pp 435-520.
(17) Low, J. J.; Goddard, W. A., III J. Am. Chem. Soc. 1984, 106, 8321: Reductive Coupling of H-H, H-C, and C-C Bonds from Pd Complexes.
(18) Zhou, X.-L.; Castro M. E.; White, J. M. Surface Science. 1990, 238, 215: Interactions of UV Photons and Low Energy Electrons with Chemisorbed Benzene on Ag(111).
(19) Wang, J.-H.; Chiang, C.-M. J. Am. Chem. Soc. 2000, 122, 11521: Observation of β-C-H Bond Activation of Allyl Groups Adsorbed on Ag(111) and an Unusual Deuterium Isotope Effect.
(20) Tjandra, S.; Zaera, F. J. Am. Chem. Soc. 1995, 117, 9749 : Thermal Reactions of Alkyl Iodide on Ni(100) Single Crystal Surface.
(21) Buelow, M. T.; Gellman, A. J. J. Mol. Catal. A: Chem. 1998, 131, 55: Correlation between Substituent Effects for Surface Reactions and Catalytic Reaction.
(22) Gellman, A. J. Acc. Chem. Res. 2000, 33, 19: Transition States for Surface-Catalyzed Chemistry.
(23) Lin, J.-L.; Bent B. E. Chem. Phys. Lett. 1992, 194, 208: C-H Vibrational Mode-Softening in Alkyl Groups Bound to Cu(111).
(24) Zheng, C.; Apeloig, Y.; Hoffmann, R. J. Am. Chem. Soc. 1988, 110, 749: Bonding and Coupling of C1 Fragments on Metal Surface.
(25) Taft, R. W.; Lewis, I. C. J. Am. Chem. Soc. 1958, 80, 2436: The General Applicability of a Fixed Scale of Inductive Effects. II. Inductive Effects of Dipolar Substituents in the Reactivities of m- and p-Substituted Derivatives of Benzene.
(26) Hansch, C.; Leo, A.; Taft, R. W. Chem. Rev. 1991, 91,165: A Survey of Hammett Substituent Constants and Resonance and Field Parameters.
(27) Gronert, S. J. Org. Chem. 2006, 71, 1209: An Alternative Interpretation of the C-H Bond Strengths of Alkanes.
(28) Siemsen, P.; Livingston R. C.; Diederich, F. Angew. Chem. Int. Ed. 2000, 39, 2632: Acetylenic Coupling: A Powerful Tool in Molecular Construction.
(29) Rosenthal, U.; Pellny, P.-M.; Kirchbauer, F. G.; Burlakov, V. V. Acc. Chem. Res. 2000, 33, 119: What Do Titano- and Zirconocenes Do with Diynes and Polyynes?
(30) Diederich, F., Tykwinski, R. R., Stang, P. J., Eds. Acetylene Chemistry: Chemistry, Biology and Materials Science; Wiley-VCH: Weinheim, Germany 2004.
電子全文 Fulltext
本電子全文僅授權使用者為學術研究之目的,進行個人非營利性質之檢索、閱讀、列印。請遵守中華民國著作權法之相關規定,切勿任意重製、散佈、改作、轉貼、播送,以免觸法。
論文使用權限 Thesis access permission:校內外都一年後公開 withheld
開放時間 Available:
校內 Campus: 已公開 available
校外 Off-campus: 已公開 available


紙本論文 Printed copies
紙本論文的公開資訊在102學年度以後相對較為完整。如果需要查詢101學年度以前的紙本論文公開資訊,請聯繫圖資處紙本論文服務櫃台。如有不便之處敬請見諒。
開放時間 available 已公開 available

QR Code