DOCSLIB.ORG

A Kinetic Study of Propylene Metathesis Over WO3-Sio2 Gel

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Kinetic Study of Propylene Metathesis Over WO3-Sio2 Gel Proceedings of the Iowa Academy of Science Volume 86 Number Article 9 1979 A Kinetic Study of Propylene Metathesis over WO3-SiO2 Gel Russell Maatman Dordt College Craig Friesema Dordt College Let us know how access to this document benefits ouy Copyright ©1979 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Maatman, Russell and Friesema, Craig (1979) "A Kinetic Study of Propylene Metathesis over WO3-SiO2 Gel," Proceedings of the Iowa Academy of Science, 86(1), 26-31. Available at: https://scholarworks.uni.edu/pias/vol86/iss1/9 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact [email protected]. Maatman and Friesema: A Kinetic Study of Propylene Metathesis over WO3-SiO2 Gel Proc. Iowa Acad. Sci. 86(1): 26-31. 1979 A Kinetic Study of Propylene Metathesis over WOa-Si02 Gel RUSSELL MAATMAN and CRAIG FRIESEMA Department of Chemistry, Dordt College, Sioux Center, Iowa 51250 Recent workers have reported anomalous results for the metathesis of propylene over WOa-Si02 gel in a flow system. One anomaly, confirmed in the present work, is an increase in catalytic activity with an increase in flow rate. The reaction was studied at a propylene partial pressure of0.37-1 atm between 435 and 493"C. Two reaction mechanisms have recently been proposed; one includes a bimolecular surface step and the other is a carbene chain mechanism. The rate law for the carbene mechanism has been developed. Attempts were made to fit the catalytic activities to the rate laws for these two mechanisms. An attempt was also made to determine whether or not the activities meet the site density criterion. This criterion states for a postulated slow step that the calculated density of active sites on the surface, determined by analyzing kinetic data using transition state theory, must be a physically possible site density. Our results are consistent with the bimolecular, but not with the carbene, rate law. However, our data are not consistent with the site density criterion for the bimolecular rate law. The theoretical methods used enable us to detect anomalies in our kinetic data, in this case the flow rate anomaly. Applying the same tests to systems reported in the literature indicates that inconsistency with a rate law or a physically possible site density is not found when there is no flow rate anomaly. INDEX DESCRIPTORS: metathesis mechanism, propylene metathesis, WOaSi02 gel, metathesis kinetics. The metathesis of propylene to ethylene and cis-2-butene occurs over copper and subsequently dried in a molecular sieve drying tube. many solid catalysts. Many of the catalysts for this reaction are mixed A conventional, all-Pyrex differential flow reactor was used. The oxides, such as the oxides of molybdenum and aluminum; cobalt, product was analyzed in an A-90-P Varian Gas Chromatograph, using a molybdenum, and aluminum; tungsten and aluminum; and tungsten and Porapak Q column and a tungsten filament thermal conductivity detec­ silicon (J). tor. In representative determinations, the ethylene:butene mole ratio We are interested here in the behavior of the WOa-Si02 gel catalyst. averaged 1.05. The true value was taken to be 1; results are reported on Moffat, Johnson, and Clark observed that this catalyst became more the basis of ethylene analysis. The catalyst was normally pretreated active with increased flow rate, and suggested that a very unusual mass with 02 for 5 hrs. at 500°. During a run the activity of the catalyst transfer problem existed (2, 3). Moffat later suggested that the anomaly increased for a period of about 2 hrs. and was then constant for at least could be explained if there were very few, but very active, sites (4). 12 hrs. This "break-in" period has been observed by others. Westhoff This explanation was offered partly because of our conclusion that and Moulijn concluded from gravimetric studies that the activity in­ some catalysts have extremely low site densities (5, 6). crease was due to a slight reduction ofW03 by propylene, with no more Luckner, McConchie, and Wills confirmed the anomalous results than 1 oxygen atom in 60 removed during the induction period (19). We obtained with the W03-Si02 gel catalyst (7). They suggested that the report only constant activities. problem arose because of a non-uniform impregnation of the silica gel It was possible during a run to change the temperature, the partial support. They did not need to invoke a low site density to interpret their pressure of propylene (P) by diluting with N., and the flow rate and, kinetic data and they were able to study the reaction under conditions after restoration of the original conditions, obtain the original activity. such that there was no flow rate anomaly. The thermal conversion was 0.2-0.3% at a flow rate of 10 ml/min and Several mechanisms for olefin metathesis have been proposed. negligible at 40 ml/min. Activities reported were calculated after the These include various forms of a mechanism which includes a bimolec­ thermal conversion was subtracted from the total conversion; the latter ular surface step; one form is the so-called four-center mechanism, in quantity was in the range 0.5-3.5%. Our error in measurement of which there is reaction between two olefin molecules adsorbed on activity, as determined from the average deviation in 7 paired determi­ adjacent pairs of sites. Recently, however, there has been considerable nations, was 3.4%. interest in a carbene mechanism, in which there is a chain reaction but not a bimolecular surface step. This mechanism has been suggested for RESULTS AND DISCUSSION heterogeneous and homogeneous liquid phase reactions and heterogen­ eous gas reactions (8-18), and is described in more detail in the Results Activity as a function of flow rate for three different catalyst weights and Discussion section. is given in Fig. 1. In Fig. 2, activity as a function of P is shown. In this paper we analyze the activity of a W03-Si02 catalyst for Arrhenius plots of the activities are given in Fig. 3 for 4 flow rate­ propylene metathesis. We have looked at the flow rate problem and catalyst weight-pretreatment combinations. have attempted to determine whether or not the results are consistent Our results agree with others in that our activities increased with with any of the proposed mechanisms. increasing flow rate. Pennella recently suggested that these anomalous results are not easily explained by an analysis of mass transfer (20). MATERIALS AND METHODS Pennella concluded for his system that reversible poison was intro­ duced into the feed stream ahead of the catalyst bed at a rate indepen­ Matheson C. P. propylene was used. No ethylene impurity was dent of the flow rate. Thus, the partial pressure of the poison decreases, detected; the non-Ca impurity was 0.09%. Both molecular sieve and with an increase in activity, as the flow rate increases at constant total Drierite drying tubes were used in the feed line. The catalyst, 6. 9 wt % pressure. If poisoning is indeed a complicating factor, we might antici­ WOa on silica gel, of 200 m2/g surface area, was provided by pate that the kinetic results for such a system cannot be reliably used in the Phillips Petroleum Company, and was used as 100-200 mesh the elucidation of the reaction mechanism. powder. Nitrogen (used to flush the reactor and to dilute the propylene) To pursue this matter further, we examine the two mechanisms for was freed of oxygen impurity by by-passing it through a tube of hot the reaction most recently proposed. We shall then examine rate data to Published by UNI ScholarWorks, 1979 1 Proceedings of the Iowa Academy of Science, Vol. 86 [1979], No. 1, Art. 9 KINETIC STUDY OF PROPYLENE METATHESIS 27 10.0 r----------------.,.------1 • 2.0 ~~.::------------------0-- ~ ,,\ ' ', \ \ ' ~/ \ \ ' .... ~ \ ', \ \ ' \ \ ' \ \ ' 8.0 1.s \ \ " \ \ ' I \ ' \ \ ' 1ii \ \ ' a... '& I' \ ', u \2 \I '-~ \ \ ' \ '~ \ ' ' -- 1 ~ \ \ ->-"' ~ \ \ i 1.0 ~ \ \ 0 6.0 :I u ~ \ \ 0 \ \ - ~• \ \ 1 E '• \ \ u \ \ 0 ~ \ \ • ·~ \ \ .!! . ~ \ \ -;: . \ \ -"' \ \ \ • ' \ \ u=' ~ \ I \ \ I ~ 4.0 \ \ I E ' • \ I \ • \ I ' \ I \ \ I 0 '- \ I ~ ' \ I >­ ' \ I .:!:: '', ____\ \1 I :;:> o.-=----__...,. ____...._ ___...._ ___~-------- g 1,• 1. o o.8 0.6 0.4 0.2 0.0 2.0 , , P, ATM. // // It II II Fig. 2. Activity vs. partial pressure of propylene; temperature, 475°C; ///'A flow rate JO ml/min; catalyst weight (normal pre-treat), 1.04 g. Circles Ill and solid line, experimental; 0, rate calculated if reaction is zero order; II/ , 1h, rate calculated if rate is proportional to p1h; 1, if proportional to P; 2, if rate is given by Eq. I. '• 1h•' and ''I'' curves fitted to P = 0 .P = I o~'----0 .......50-----+------'------'---' 100 150 200 points; "2" curve fitted to P = 0.67. P = I points. FLOW RATE, cm~mln Fig. I. Activity vs. flow rate. Square, 0.050. g catalyst. 475°; circle, 0.100 g catalyst, 466°; triangle, 1.00 g catalyst 477°. steps are conceivable: k1a l;I M + CaHs - H - C = M + C2H4 (2a) I determine whether either or both of the postulated mechanisms are possible. k1b l;I l;I Mz + CaHs - H - C = M + CHa - C = M (2b) The four-center mechanism I II The kinetic scheme for this mechanism is that which applies to a bimolecular surface reaction; it is not necessary that there be four Either Mor Mz can be considered a site.
Load more

Recommended publications
  • Olefin-Metathesis Catalysts for the Preparation of Molecules and Materials (Nobel Lecture 2005)**
    NOBEL LECTURES DOI: 10.1002/adsc.200600523 Olefin-Metathesis Catalysts for the Preparation of Molecules and Materials (Nobel Lecture 2005)** Robert H. Grubbsa,* a Victor and Elizabeth Atkins Professor of Chemistry Arnold and Mabel Beckman Laboratories of Chemical Synthesis California Institute of Technology, Pasadena, CA 91125, USA Fax : (+1)-626–564–9297 [**] Copyright The Nobel Foundation 2005. We thank the Nobel Foundation, Stockholm, for permission to print this lecture Received: February 21, 2006 This is a story of our exploration of the olefin-meta- ly added to this reaction, 1-butene was again ob- thesis reaction, a reaction that has been the major served. This discovery has since served as the founda- emphasis of my independent research. As with all sto- tion for an amazing array of nickel chemistry and cat- ries of scientific discovery, there are three compo- alysis. In addition, as nickel had been found to possess nents: the discoveries, the resulting applications, and, unexpected reactivity, other metal salts were also in- perhaps the most important of all, the people in- vestigated. In particular, when titanium and zirconium volved. Starting from observations made from seem- halides were used in combination with alkyl alumi- ingly unrelated work, our investigations into the fun- num compounds, a new form of polyethylene was ob- damental chemistry of this transformation have been tained. Natta further demonstrated that similar cata- an exciting journey, with major advances often result- lysts could promote the formation of stereoregular ing from complete surprises, mistakes, and simple in- polymers from propylene. The 1963 Nobel Prize in tuition. Ultimately, these efforts have contributed to Chemistry was awarded to Ziegler and Natta for this olefin metathesis becoming the indispensable synthet- work.
    [Show full text]
  • Part I: Carbonyl-Olefin Metathesis of Norbornene
    Part I: Carbonyl-Olefin Metathesis of Norbornene Part II: Cyclopropenimine-Catalyzed Asymmetric Michael Reactions Zara Maxine Seibel Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences COLUMBIA UNIVERSITY 2016 1 © 2016 Zara Maxine Seibel All Rights Reserved 2 ABSTRACT Part I: Carbonyl-Olefin Metathesis of Norbornene Part II: Cyclopropenimine-Catalyzed Asymmetric Michael Reactions Zara Maxine Seibel This thesis details progress towards the development of an organocatalytic carbonyl- olefin metathesis of norbornene. This transformation has not previously been done catalytically and has not been done in practical manner with stepwise or stoichiometric processes. Building on the previous work of the Lambert lab on the metathesis of cyclopropene and an aldehyde using a hydrazine catalyst, this work discusses efforts to expand to the less stained norbornene. Computational and experimental studies on the catalytic cycle are discussed, including detailed experimental work on how various factors affect the difficult cycloreversion step. The second portion of this thesis details the use of chiral cyclopropenimine bases as catalysts for asymmetric Michael reactions. The Lambert lab has previously developed chiral cyclopropenimine bases for glycine imine nucleophiles. The scope of these catalysts was expanded to include glycine imine derivatives in which the nitrogen atom was replaced with a carbon atom, and to include imines derived from other amino acids. i Table of Contents List of Abbreviations…………………………………………………………………………..iv Part I: Carbonyl-Olefin Metathesis…………………………………………………………… 1 Chapter 1 – Metathesis Reactions of Double Bonds………………………………………….. 1 Introduction………………………………………………………………………………. 1 Olefin Metathesis………………………………………………………………………… 2 Wittig Reaction…………………………………………………………………………... 6 Tebbe Olefination………………………………………………………………………... 9 Carbonyl-Olefin Metathesis…………………………………………………………….
    [Show full text]
  • Wacker Oxidation ~Anti-Markovnikov~
    Anti-Markovnikov Olefin Functionalization ~Prof. Robert H. Grubbs’ Work~ 4th Literature Seminar July 5, 2014 Soichi Ito (D1) Contents 1. Introduction • Flow of Prof. Grubbs’ Research • Markovnikov’s Rule • Wacker Oxidation 2. Grubbs’ Work • Substrate-Controlled Wacker Oxidation • Catalyst-Controlled Wacker-Type Oxidation 2 Introduction ~Flow of Research~ Olefin Metathesis Anti-Markovnikov Wacker Oxidation of Terminal Olefin Substrate-Controlled Wacker Oxidation of Internal Olefin Z-Selective Metathesis Hydration Ethenolysis + Reduction Hydroamination Z-Selective Ethenolysis Catalyst-Controlled Decarbonylative Dehydration Hydrophosphonation Production of Terminal Olefin Functionalization of Terminal Olefin 3 Introduction ~Markovnikov’s Rule~ Two-Step Two-Step (+1C) 4 Robert H. Grubbs et al. Science, 2011, 333, 1609. Anti-Markovnikov Hydration of Olefins • One-Step William C. Trogler et al. Science 1986, 233, 1069. This work was difficult to reproduce. Inorg. Chem. 1988, 27, 3151. • One-Step with Activated Olefins Robert G. Bergman and F. Dean Toste et al. J. Am. Chem. Soc. 2003, 125, 8696. Ben L. Feringa and Gerard Roelfes et al. Nat. Chem. 2010, 2, 991. • Three-Step 5 Shannon S. Stahl et al. J. Am. Chem. Soc. 2010, 132, 15116. Anti-Markovnikov Wacker Oxidation / Reduction Strategy Oxidation cycle must be compatible with the reduction cycle. aldehyde-selective Wacker Oxidation 6 Robert H. Grubbs et al. Science, 2011, 333, 1609. Introduction ~Wacker-Tsuji Oxidation~ • 1894 F. C. Phillips reported stoichiometric reaction. • 1959 J. Smidt et al. reported the Wacker process. (oxidation of ethylene to acetaldehyde) Investigations for convenient laboratory methods • 1976 J. Tsuji et al. reported PdCl2, CuCl / DMF, H2O method. “Terminal alkenes may be viewed as masked ketones.” 7 Jacques Muzart Tetrahedron 2007, 63, 7505.
    [Show full text]
  • Self-Metathesis of 1-Octene Using Alumina-Supported Re2o7 in Supercritical CO2
    Top Catal DOI 10.1007/s11244-008-9154-4 ORIGINAL PAPER Self-Metathesis of 1-Octene Using Alumina-Supported Re2O7 in Supercritical CO2 Massimo Fabris Æ Cindy Aquino Æ Antony J. Ward Æ Alvise Perosa Æ Thomas Maschmeyer Æ Maurizio Selva Ó Springer Science+Business Media, LLC 2009 Abstract In this contribution we describe the use of basic science has been applied for the benefit of man, heterogeneous catalysts for the liquid-phase self-metathesis society and the environment’’.1 Their contribution was of 1-octene in supercritical CO2. Our work aims at recognized for understanding the mechanism, and for addressing the mass-transfer problems associated with such developing very efficient and selective discrete metal- reaction systems. By coupling a heterogeneous supported based catalysts. Re2O7 catalyst with the use of scCO2, the self-metathesis Nonetheless, one should not forget that the metathesis of 1-octene takes place by and large much more rapidly reaction using heterogeneous catalysis has been an estab- than in traditional solvent media, and furthermore, by using lished industrial process since 1966, based on the use of scCO2 the overall efficiency and sustainability of the supported (usually on silica and alumina) metal oxides transformation can be improved. such as tungsten, nickel, cobalt, rhenium, and molybde- num. Three significant examples come to mind and are Keywords Metathesis Á 1-Octene Á Supercritical CO2 Á here recalled briefly. [1]. Re/Al O 2 3 1. The historic Phillips triolefin process for the produc- tion of ethene and 2-butene from propene using a WO /SiO catalyst, [2] that was shut down in 1972 1 Introduction 3 2 after 6 years of operation due to increased demand for propene, and later reutilized in the reverse direction to The metathesis of olefins is a very elegant and widely produce propene.
    [Show full text]
  • Introduction
    1 Chapter 1 INTRODUCTION Significant research efforts in the field of transition metal catalysis have led to the development of powerful methods for the formation of C–C and C–heteroatom bonds. Appropriate design of the catalyst and reaction conditions, along with careful choice of the substrate, can enable new and challenging transformations to proceed in high yield and selectivity. In this thesis, three categories of such transformations are presented: cross- coupling reactions to form carbon–silicon bonds, aldehyde-selective Wacker oxidations of fluorinated olefins, and olefin metathesis catalyzed by aminophosphine-ligated ruthenium complexes. Nickel-catalyzed cross-coupling has proven to be a very effective strategy for the addition of organometallic reagents to unactivated alkyl electrophiles. In particular, secondary alkyl halides are useful coupling partners, despite previously being considered to exhibit poor reactivity in comparison to aryl and alkenyl electrophiles, due to challenging oxidative addition and competitive b-hydride elimination. While this class of reactions has predominantly been applied to the formation of C–C bonds, the extension of this strategy to the formation of C–B bonds presented by Fu and coworkers inspired the work presented in the second chapter of this thesis, which details the development of a nickel-catalyzed cross- coupling reaction of unactivated alkyl bromides and silylzinc nucleophiles, resulting in C–Si bond formation. A brief overview of established strategies to form C–Si bonds, as well as some of the current challenges, is discussed. The palladium-catalyzed Wacker oxidation is a powerful tool for the oxidation of terminal olefins. However, controlling the regioselectivity of this process (i.e.
    [Show full text]
  • Manipulating Selectivity and Reactivity in Palladium-Catalyzed Oxidation Reactions
    Manipulating Selectivity and Reactivity in Palladium-Catalyzed Oxidation Reactions Thesis by Zachary Kimble Wickens In Partial Fulfillment of the Requirements for the degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2015 (Defended June 2nd, 2015) © 2015 Zachary Kimble Wickens All Rights Reserved 1 Dedicated to my parents for never pushing me to become a scientist 2 Acknowledgments The work I have the pleasure of sharing with you in this thesis would have been completely impossible without the help (both emotional and intellectual) of a tremendously large number of people. First, I want to thank my advisor, Bob Grubbs. I truly could not have asked for a more incredible thesis advisor. Since the beginning of my time at Caltech, you have subtly guided me towards the water but never forced me to drink. You have given me independence in choosing which projects to pursue and the directions these projects go, but always provided suggestions and hints along the way that have kept me on track. I know you will continue to provide great advice and strong support even long after I've left Caltech. Thanks for being my invisible safety net over the last five years. I would have never even considered pursuing a Ph.D in chemistry in the first place if it weren't for the fantastic chemistry faculty at Macalester College. Rebecca Hoye, Ronald Brisbois, Paul Fischer, Keith Kuwata, Thomas Varberg and Katherine Splan, you were all tremendously influential in my life. You taught me how to see the exciting puzzles that are scattered throughout the field of chemistry.
    [Show full text]
  • Ruthenium-Based Olefin Metathesis Catalysts Coordinated with N-Heterocyclic
    Ruthenium-Based Olefin Metathesis Catalysts Coordinated with N-Heterocyclic Carbene Ligands: Synthesis and Applications Thesis by John Philip Morgan In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 2002 (Submitted September 12, 2002) ii 2002 John Philip Morgan All Rights Reserved iii To my family and my friends, I’d never be here if you weren’t there. iv “No matter where you go, there you are.” — Buckaroo Banzai, as told to Earl Mac Rausch [The Hitchhiker’s Guide to the Galaxy is superior to this thesis in two respects.] “First, it is slightly cheaper; and second, it has the words DON’T PANIC inscribed in large, friendly letters on its cover.” — Douglas Adams v Chapter 0: A Concise Synthesis of the Cocktail “Peter’s Catalyst” Experimental Section. General. All materials were used as obtained from the Athenaeum, Vons, or Ralph’s. “Cranberry juice” may refer to any “cocktail” preparation. “Grapefruit juice” may also be a “cocktail” preparation, but not a “sour mix.” Visual spectroscopy is used to estimate color of final preparation. Synthesis of “Peter’s Catalyst” (Compound 1). A clean, dry whisky glass is charged with ice (3-5 cubes), grapefruit juice (1 oz., 1 equiv.), cranberry juice (4 shots, approximately 2 equiv.), blue curacaó (0.5 shot, 0.25 equiv.), and vodka (1- 2 shots, 0.5-1.0 eq. to taste). The reaction mixture is stirred briefly until the color is homogeneous (5 s). An additional aliquot of cranberry juice is added until the reaction mixture has achieved a dark purplish color.
    [Show full text]
  • Olefins from Biomass Intermediates: a Review
    catalysts Review Review OlefinsOlefins fromfrom BiomassBiomass Intermediates:Intermediates: AA ReviewReview 1 1,2, VasilikiVasiliki Zacharopoulou Zacharopoulou1 andand AngelikiAngeliki A.A. LemonidouLemonidou 1,2,** 1 Department of Chemical Engineering, Aristotle University of Thessaloniki, University Campus, 1 Department of Chemical Engineering, Aristotle University of Thessaloniki, University Campus, Thessaloniki 54124, Greece; [email protected] 54124 Thessaloniki, Greece; [email protected] 2 Chemical Process Engineering Research Institute (CERTH/CPERI), P.O. Box 60361 Thermi, 2 Chemical Process Engineering Research Institute (CERTH/CPERI), P.O. Box 60361 Thermi, Thessaloniki 57001, Greece 57001 Thessaloniki, Greece * Correspondence: [email protected]; Tel.: +30‐2310‐996‐273 * Correspondence: [email protected]; Tel.: +30-2310-996-273 Received: 16 November 2017; Accepted: 19 December 2017; Published: Received: 16 November 2017; Accepted: 19 December 2017; Published: 23 December 2017 Abstract:Abstract: Over the last decade, increasing demand for olefinsolefins and theirtheir valuablevaluable productsproducts hashas promptedprompted researchresearch onon novelnovel processesprocesses andand technologiestechnologies forfor theirtheir selectiveselective production.production. As olefinsolefins are predominatelypredominately dependent on fossil resources, their production is limited by thethe finitefinite reservesreserves and the associated economic and environmental concerns.concerns. The need for alternative routes for
    [Show full text]
  • PDF (Chapter 1.Pdf)
    1 Chapter 1 Introduction The olefin metathesis reaction is a powerful synthetic tool that scrambles the carbon atoms of carbon–carbon double bonds and creates new carbon–carbon double bonds. The mechanism of the reaction was proposed by Chauvin in 1971, and it is still accepted today (Scheme 1.1).1 The key component to any olefin metathesis reaction is a transition metal species bearing a metal–carbon double bond (carbene or alkylidene). An alkene approaches the alkylidene (1) and undergoes a [2+2]-cycloaddition that generates a new carbon–carbon bond and affords a metallocyclobutane (2). A retro-[2+2], where different bonds break than were formed, generates a new olefin and a new metal alkylidene. R2 R1 R1 M M M 1 R1 R2 R1 M M M R R 2 R 1 1 R1 R 2 2 Scheme 1.1. Accepted olefin metathesis mechanism. This simple transformation has been used in a wide variety of ways to synthesize simple organic molecules, complex natural products, supramolecules, and polymers.2 Some of the common reactions are shown in Figure 1.1. Cross-metathesis (CM), ring- opening/cross metathesis (ROCM), and ring-closing metathesis are used in small molecule synthesis, and acyclic diene metathesis polymerization (ADMET) and ring- 2 opening metathesis polymerization (ROMP) are processes that generate oligomers and polymers. These reactions are reversible, and in many cases the driving force for product formation is the release of gaseous by-products such as ethylene or the release of ring strain. Reactions used in small molecule synthesis cross-metathesis (CM) R R1 1 R2 R2 ring-opening/cross metathesis (ROCM) R1 R1 ring-closing metathesis (RCM) Reactions used in polymer synthesis acyclic diene metathesis polymerization (ADMET) n n ring-opening metathesis polymerization (ROMP) n Figure 1.1.
    [Show full text]
  • Synthesis of Novel Dienes and Cyclic Compounds Via Olefin Metathesis Reactions Catalyzed by the Second Generation Grubbs Catalyst
    University of Tennessee at Chattanooga UTC Scholar Student Research, Creative Works, and Honors Theses Publications 5-2015 Synthesis of novel dienes and cyclic compounds via olefin metathesis reactions catalyzed by the second generation Grubbs catalyst Patrick Joseph Carey University of Tennessee at Chattanooga, [email protected] Follow this and additional works at: https://scholar.utc.edu/honors-theses Part of the Chemistry Commons Recommended Citation Carey, Patrick Joseph, "Synthesis of novel dienes and cyclic compounds via olefin metathesis eactionsr catalyzed by the second generation Grubbs catalyst" (2015). Honors Theses. This Theses is brought to you for free and open access by the Student Research, Creative Works, and Publications at UTC Scholar. It has been accepted for inclusion in Honors Theses by an authorized administrator of UTC Scholar. For more information, please contact [email protected]. Synthesis of Novel Dienes and Cyclic Compounds via Olefin Metathesis Reactions Catalyzed by the Second Generation Grubbs Catalyst Patrick J. Carey Departmental Honors Thesis The University of Tennessee at Chattanooga Department of Chemistry Project Director: Dr. Kyle S. Knight Examination Date: March 30, 2015 Members of Examination Committee: Dr. Titus V. Albu Dr. Tom R. Rybolt Dr. D. Stephen Nichols, III Examining Committee Signatures: _________________________________________________________ Project Director _________________________________________________________ Department Examiner _________________________________________________________
    [Show full text]
  • Application of Olefin Cross-Metathesis to the Synthesis of Biologically Active Natural Products Joëlle Prunet
    Application of Olefin Cross-Metathesis to the Synthesis of Biologically Active Natural Products Joëlle Prunet To cite this version: Joëlle Prunet. Application of Olefin Cross-Metathesis to the Synthesis of Biologically Active Natural Products. Current Topics in Medicinal Chemistry, Bentham Science Publishers, 2005, 5, pp.1559. hal-00085197 HAL Id: hal-00085197 https://hal.archives-ouvertes.fr/hal-00085197 Submitted on 12 Jul 2006 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Application of Olefin Cross-Metathesis to the Synthesis of Biologically Active Natural Products Joëlle Prunet Laboratoire de Synthèse Organique, UMR CNRS 7652, Ecole Polytechnique, DCSO, 91128 Palaiseau, France [email protected] Introduction Over the past decade, olefin metathesis has become a powerful tool in organic synthesis, and is widely used by chemists in other disciplines as well [1]. Alkene cross-metathesis (CM) (Scheme 1) emerged later than the ring-closing process, as many undesired products such as homodimers often plagued the reaction [2]. The problems to overcome for a successful CM reaction involve the control of chemo- and stereoselectivity, and they have been addressed with success with the development of the more active —second-generation“ ruthenium catalysts [Ru]-II [3] and [Ru]-IV [4] (Fig.
    [Show full text]
  • Nonlinear Polymeric Architectures Via Olefin Metathesis
    CHAPTER 1 Introduction to Olefin Metathesis and Its Applications in Polymer Synthesis 2 Olefin Metathesis Olefin metathesis is a metal-catalyzed transformation, which acts on carbon- carbon double bonds and rearranges them via cleavage and reassembly.1-5 While the reaction itself was discovered in the mid-1950s, its now generally accepted mechanism was not proposed until 1971. 6 According to this mechanism, first introduced by Chauvin, the coordination of an olefin to a metal carbene catalytic species leads to the reversible formation of a metallacyclobutane (Scheme 1.1). This intermediate then proceeds by cycloreversion via either of the two possible paths: 1) non-productive—resulting in the re-formation of the starting materials or 2) product-forming—yielding an olefin that has exchanged a carbon with the catalyst’s alkylidene. Since all of these processes are fully reversible (Scheme 1.1), only statistical mixtures of starting materials as well as all of possible rearrangement products are produced in the absence of thermodynamic driving forces. Scheme 1.1. General mechanism of olefin metathesis. 6 Fortunately for the organic and polymer chemistry communities, the olefin metathesis reaction’s thermodynamic equilibrium can be easily influenced. There are two major approaches that are commonly employed to drive the reaction towards the desired products. One tactic is to rely on Le Chatelier’s principle by continuously removing one of the products from the reaction system in order to shift the equilibrium in favor of the other product. This method is especially effective in the case of cross metathesis (CM) 7 reactions involving terminal olefins, ring-closing metathesis (RCM) 8,9 and acyclic diene metathesis polymerization (ADMET),10-14 because the volatile ethylene gas by-product formed in these processes can be easily removed (Scheme 1.2).
    [Show full text]