DOCSLIB.ORG

5.6 Free-Radical Addition of Hydrogen Bromide to Alkenes 201

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
5.6 Free-Radical Addition of Hydrogen Bromide to Alkenes 201 05_BRCLoudon_pgs5-0.qxd 12/5/08 2:47 PM Page 200 200 CHAPTER 5 • ADDITION REACTIONS OF ALKENES PROBLEMS 5.13 Give the products (if any) expected from the treatment of each of the following compounds with ozone followed by dimethyl sulfide. (a) 3-methyl-2 pentene (b) A CH2 0 (c) cyclooctene (d) 2-methylpentane 5.14 Give the products (if any) expected when the compounds in Problem 5.13 are treated with ozone followed by aqueous hydrogen peroxide. 5.15 In each case, give the structure of an eight-carbon alkene that would yield each of the following compounds (and no others) after treatment with ozone followed by dimethyl sulfide. (a) O (b) CH3CH2CH2CHA O (c) O S S O A CH(CH2)5C CH3 L S O 5.16 What aspect of alkene structure cannot be determined by ozonolysis? FREE-RADICAL ADDITION OF HYDROGEN 5.6 BROMIDE TO ALKENES A. The Peroxide Effect Recall that addition of HBr to alkenes is a regioselective reaction in which the bromine is directed to the carbon of a double bond with the greater number of alkyl groups (Sec. 4.7A). For example, 1-pentene reacts with HBr to give almost exclusively 2-bromopentane: CH3CH2CH2CHA CH2 H Br CH3CH2CH2CHCH3 (5.41) 1-pentene + L "Br 2-bromopentane (79% yield) For many years, results such as this were at times difficult to reproduce. Some investigators found that the addition of HBr was a highly regioselective reaction, as shown in Eq. 5.41. Oth- ers, however, obtained mixtures of constitutional isomers in which the second isomer had bromine bound at the carbon of the double bond with fewer alkyl groups. In the late 1920s, Mor- ris Kharasch (1895–1957) of the University of Chicago began investigations that led to a solu- tion of this puzzle. He found that when traces of peroxides (compounds of the general structure R O O R) are added to the reaction mixture, the regioselectivity of HBr addition is re- versed!L LIn otherL words, 1-pentene was found to react in the presence of peroxides so that the bromine adds to the less branched carbon of the double bond: O O S S PhC O O C Ph LbenzoylL L peroxideL L (small amount used) CH3CH2CH2CHA CH2 H Br CH3CH2CH2CH2CH2 Br (5.42) 1-pentene + L 1-bromopentane L (96% yield) (Contrast this result with that in Eq. 5.41.) This reversal of regioselectivity in HBr addition is called the peroxide effect. 05_BRCLoudon_pgs5-0.qxd 12/5/08 2:47 PM Page 201 5.6 FREE-RADICAL ADDITION OF HYDROGEN BROMIDE TO ALKENES 201 Because the regioselectivity of ordinary HBr addition is described by Markovnikov’s rule (p. 148), the peroxide-promoted addition is sometimes said to have anti-Markovnikov regioselectivity. This means simply that the bromine is directed to the carbon of the alkene double bond with fewer alkyl sub- stituents. It was also found that light further promotes the peroxide effect. When Kharasch and his colleagues scrupulously excluded peroxides and light from the reaction, they found that HBr addition has the “normal” regioselectivity shown in Eq. 5.41. The peroxide effect is observed with all alkenes in which alkyl substitution at the two car- bons of the double bond is different. In other words, in the presence of peroxides, the addition of HBr to alkenes occurs such that the hydrogen is bound to the carbon of the double bond bearing the greater number of alkyl substituents. Furthermore, the peroxide-promoted reac- tion is faster than HBr addition in the the absence of peroxides. Very small amounts of perox- ides are required to bring about this effect. H C HBr 3 peroxides $ CH CH Br faster $ 2 H3C L L $ H3C $C A CH2 (5.43) CH3 HBr H3C no peroxides H3C "C CH3 slower L L "Br The regioselectivity of HI or HCl addition to alkenes is not affected by the presence of per- oxides. For these hydrogen halides, the normal regioselectivity of addition predominates, whether peroxides are present or not. (The reason for this difference is discussed in Sec. 5.6E.) The addition of HBr to alkenes in the presence of peroxides occurs by a mechanism that is completely different from that for normal addition. This mechanism involves reactive interme- diates known as free radicals. To appreciate the reasons for the peroxide effect, then, let’s di- gress and learn some basic facts about free radicals. B. Free Radicals and the “Fishhook” Notation In all reactions considered previously, we used a curved-arrow notation that indicates the movement of electrons in pairs. The dissociation of HBr, for example, is written (5.44) H Br H| Br _ L 2 3 + 3 2 3 In this reaction, bromine takes both electrons2 of the H Br2 covalent bond to give a bromide ion, and the hydrogen becomes an electron-deficient species,L the proton. This type of bond breaking is an example of a heterolysis, or heterolytic cleavage (hetero different; lysis bond-breaking). In a heterolytic process, electrons involved in the process= “move” in pairs.= Thus, a heterolysis is a bond-breaking process that occurs with electrons “moving” in pairs. However, bond rupture can occur in another way. An electron-pair bond may also break so that each bonding partner takes one electron of the chemical bond. H Br H Br (5.45) L 2 3 8 + 8 2 3 In this process, a hydrogen atom and a2 bromine atom are produced.2 As you should verify, these atoms are uncharged. This type of bond breaking is an example of a homolysis, or homolytic cleavage (homo the same; lysis bond-breaking). In a homolytic process, electrons involved = = 05_BRCLoudon_pgs5-0.qxd 12/5/08 2:47 PM Page 202 202 CHAPTER 5 • ADDITION REACTIONS OF ALKENES in the process “move” in an unpaired way. Thus, a homolysis is a bond-breaking process that oc- curs with electrons moving in an unpaired fashion. A different curved-arrow notation is used for homolytic processes. In this notation, called the fishhook notation, electrons move individually rather than in pairs. This type of electron flow is represented with singly barbed arrows, or fishhooks; one fishhook is used for each electron: H Br H Br (5.46) L 2 3 8 + 8 2 3 Homolytic bond cleavage is not restricted2 to diatomic molecules.2 For example, peroxides, because of their very weak O O bonds, are prone to undergo homolytic cleavage: 1 1 1 L (CH3)3CO O C(CH3)3 2(CH3)3CO (5.47) L 1 L 1 L L 1 8 di-tert-butyl peroxide tert-butoxy radical The fragments on the right side of this equation possess unpaired electrons. Any species with at least one unpaired electron is called a free radical. The hydrogen atom and the bromine atom on the right side of Eq. 5.46, as well as the tert-butoxy radical on the right side of Eq. 5.47, are all examples of free radicals. Radicals Bound and Free The “R” used in the R-group notation (Sec. 2.9B) comes from the word radical. In the mid-1900s, R groups were called “radicals.”Thus, the CH3 group in CH3CH2OH might have been referred to as the “methyl radical.”Such R groups, when not bonded to anything, were then said to be “free radicals.” Thus, CH3 was said to be the “methyl free radical.”Nowadays we simply use the word group to refer to a group8 of atoms (for example, methyl group) in a compound; we reserve the word radical for a species with an unpaired electron. PROBLEMS 5.17 Draw the products of each of the following transformations shown by the fishhook notation. Br (a) (CH3)3C C(CH3)3 (b) L 8 12 3 (CH3)2C A CH2 (c) [H2C A CH CH A CH CH2 ] L L 8 (d) R CH2 CH2 L L 8 5.18 Indicate whether each of the following reactions is homolytic or heterolytic, and tell how you know. Write the appropriate fishhook or curved-arrow notation for each. (a) H2OH| _ OH 2 + 3 2 (b) CH23CH2OH CH3O 2 CH3CHOH CH3OH + 2 8 + 2 8 2 2 C. Free-Radical Chain Reactions Although a few stable free radicals are known, most free radicals are very reactive. When they are generated in chemical reactions, they generally behave as reactive intermediates—that is, they react before they can accumulate in significant amounts. This section shows how free rad- icals are involved as reactive intermediates in the peroxide-promoted addition of HBr to alkenes. This discussion will provide the basis for a general understanding of free-radical re- actions, as well as the peroxide effect in HBr addition, which is the subject of the next section. 05_BRCLoudon_pgs5-0.qxd 12/5/08 2:47 PM Page 203 5.6 FREE-RADICAL ADDITION OF HYDROGEN BROMIDE TO ALKENES 203 The vast preponderance of free-radical reactions can be classified as free-radical chain re- actions. A free-radical chain reaction involves free-radical intermediates and consists of the following fundamental reaction steps: 1. initiation steps, 2. propagation steps, and 3. termination steps. Let’s examine each of these steps using the peroxide-promoted addition of HBr to alkenes as an example of a typical free-radical reaction. (The reason for the “chain reaction” terminology will become apparent.) Initiation In the initiation steps, the free radicals that take part in subsequent steps of the reaction are formed from a free-radical initiator, which is a molecule that undergoes homol- ysis with particular ease.
Load more

Recommended publications
  • 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]
  • Title Crystallization of Stereospecific Olefin Copolymers (Special Issue on Physical Chemistry) Author(S) Sakaguchi, Fumio; Kita
    Crystallization of Stereospecific Olefin Copolymers (Special Title Issue on Physical Chemistry) Author(s) Sakaguchi, Fumio; Kitamaru, Ryozo; Tsuji, Waichiro Bulletin of the Institute for Chemical Research, Kyoto Citation University (1966), 44(4): 295-315 Issue Date 1966-10-31 URL http://hdl.handle.net/2433/76134 Right Type Departmental Bulletin Paper Textversion publisher Kyoto University Crystallization of Stereospecifie Olefin Copolymers Fumio SAKAGUCHI,Ryozo KITAMARU and Waichiro TSUJI* (Tsuji Laboratory) Received August 13, 1966 The stereoregularity of isotactic poly(4-methyl-1-pentene) was characterized and isomorphism phenomena were examined for the copolymeric systems of 4-methyl-1-pentene with several olefins in order to study the crystallization phenomena in these olefin copoly- mers polymerized with stereospecific catalysts. The structural heterogeneity or the fine crystalline structure of poly(4-methyl-1-pentene) could be correlated with its molecular structure by viewing this stereoregular homopolymer as if it were a copolymer. Cocrystallization or isomorphism phenomenon was recognized for the copolymeric systems of 4-methyl-1-pentene with butene-1, pentene-1, decene-1 and 3-methyl-1-butene, while no evidence of the phenomenon was obtained for the copolymeric systems with styrene and propylene. The degree of the isomorphism of those copolymers was discussed with the informations on the crystalline phases obtained from the X-ray study, on the constitution of the copolymeric chains in the amorphous phases obtained from the viscoelastic studies and on the other thermodynamical properties of these systems. INTRODUCTION Many works have been made with regard to the homopolymerization of olefins with stereospecific catalysts, i. e. complex catalysts composed of the combination of organometallic compound and transitional metallic compound.
    [Show full text]
  • Syntheses and Eliminations of Cyclopentyl Derivatives David John Rausch Iowa State University
    Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1966 Syntheses and eliminations of cyclopentyl derivatives David John Rausch Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Organic Chemistry Commons Recommended Citation Rausch, David John, "Syntheses and eliminations of cyclopentyl derivatives " (1966). Retrospective Theses and Dissertations. 2875. https://lib.dr.iastate.edu/rtd/2875 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. This dissertation has been microfilmed exactly as received 66—6996 RAUSCH, David John, 1940- SYNTHESES AND ELIMINATIONS OF CYCLOPENTYL DERIVATIVES. Iowa State University of Science and Technology Ph.D., 1966 Chemistry, organic University Microfilms, Inc., Ann Arbor, Michigan SYNTHESES AND ELIMINATIONS OF CYCLOPENTYL DERIVATIVES by David John Rausch A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of The Requirements for the Degree of DOCTOR OF PHILOSOPHY Major Subject: Organic Chemistry Approved : Signature was redacted for privacy. Signature was redacted for privacy. Head of Major Department Signature was redacted for privacy. Iowa State University Of Science and Technology Ames, Iowa 1966 ii TABLE OF CONTENTS VITA INTRODUCTION HISTORICAL Conformation of Cyclopentanes Elimination Reactions RESULTS AND DISCUSSION Synthetic Elimination Reactions EXPERIMENTAL Preparation and Purification of Materials Procedures and Data for Beta Elimination Reactions SUMMARY LITERATURE CITED ACKNOWLEDGEMENTS iii VITA The author was born in Aurora, Illinois, on October 24, 1940, to Mr.
    [Show full text]
  • Properties and Synthesis. Elimination Reactions of Alkyl Halides
    P1: PBU/OVY P2: PBU/OVY QC: PBU/OVY T1: PBU Printer: Bind Rite JWCL234-07 JWCL234-Solomons-v1 December 8, 2009 21:37 7 ALKENES AND ALKYNES I: PROPERTIES AND SYNTHESIS. ELIMINATION REACTIONS OF ALKYL HALIDES SOLUTIONS TO PROBLEMS 7.1 (a) ( E )-1-Bromo-1-chloro-1-pentene or ( E )-1-Bromo-1-chloropent-1-ene (b) ( E )-2-Bromo-1-chloro-1-iodo-1-butene or ( E )-2-Bromo-1-chloro-1-iodobut-1-ene (c) ( Z )-3,5-Dimethyl-2-hexene or ( Z )-3,5-Dimethylhex-2-ene (d) ( Z )-1-Chloro-1-iodo-2-methyl-1-butene or ( Z )-1-Chloro-1-iodo-2-methylbut-1-ene (e) ( Z,4 S )-3,4-Dimethyl-2-hexene or ( Z,4 S )-3,4-Dimethylhex-2-ene (f) ( Z,3 S )-1-Bromo-2-chloro-3-methyl-1-hexene or (Z,3 S )-1-Bromo-2-chloro-3-methylhex-1-ene 7.2 < < Order of increasing stability 7.3 (a), (b) H − 2 ∆ H° = − 119 kJ mol 1 Pt 2-Methyl-1-butene pressure (disubstituted) H2 − ∆ H° = − 127 kJ mol 1 Pt 3-Methyl-1-butene pressure (monosubstituted) H2 − ∆ H° = − 113 kJ mol 1 Pt 2-Methyl-2-butene pressure (trisubstituted) (c) Yes, because hydrogenation converts each alkene into the same product. 106 CONFIRMING PAGES P1: PBU/OVY P2: PBU/OVY QC: PBU/OVY T1: PBU Printer: Bind Rite JWCL234-07 JWCL234-Solomons-v1 December 8, 2009 21:37 ALKENES AND ALKYNES I: PROPERTIES AND SYNTHESIS 107 H H (d) > > H H H (trisubstituted) (disubstituted) (monosubstituted) Notice that this predicted order of stability is confirmed by the heats of hydro- genation.
    [Show full text]
  • Chem 51B Chapter 15 Notes
    Lecture Notes Chem 51B S. King Chapter 15 Radical Reactions I. Introduction A radical is a highly reactive intermediate with an unpaired electron. Radicals are involved in oxidation reactions, combustion reactions, and biological reactions. Structure: compare with: compare with: Stability: Free radicals and carbocations are both electron deficient and they follow a similar order of stability: R R H H , > R C > R C > R C > H C R H H H • like carbocations, radicals can be stabilized by resonance. H H H H C C C C H C CH3 H C CH3 H H • unlike carbocations, no rearrangements are observed in free radical reactions. Q. How are free radicals formed? A. Free radicals are formed when bonds break homolytically: 103 Look @ the arrow pushing: Notice the fishhook arrow! It shows movement of a single electron: Compare with heterolytic bond cleavage: A double-headed arrow shows movement of a pair of electrons: Nomenclature: bromide ion bromine atom Bromine (molecule) II. General Features of Radical Reactions Radicals are formed from covalent bonds by adding energy in the form of heat or light (hν). Some radical reactions are carried out in the presence of radical initiators, which contain weak bonds that readily undergo homolysis. The most common radical initiators are peroxides (ROOR), which contain the weak O−O bond. A. Common Reactions of Radicals: Radicals undergo two common reactions: they react with σ-bonds and they add to π-bonds. 1. Reaction of a Radical X• with a C−H bond A radical X• abstracts a H atom from a C−H bond to form H−X and a carbon radical: 104 2.
    [Show full text]
  • Reactions of Alkenes and Alkynes
    05 Reactions of Alkenes and Alkynes Polyethylene is the most widely used plastic, making up items such as packing foam, plastic bottles, and plastic utensils (top: © Jon Larson/iStockphoto; middle: GNL Media/Digital Vision/Getty Images, Inc.; bottom: © Lakhesis/iStockphoto). Inset: A model of ethylene. KEY QUESTIONS 5.1 What Are the Characteristic Reactions of Alkenes? 5.8 How Can Alkynes Be Reduced to Alkenes and 5.2 What Is a Reaction Mechanism? Alkanes? 5.3 What Are the Mechanisms of Electrophilic Additions HOW TO to Alkenes? 5.1 How to Draw Mechanisms 5.4 What Are Carbocation Rearrangements? 5.5 What Is Hydroboration–Oxidation of an Alkene? CHEMICAL CONNECTIONS 5.6 How Can an Alkene Be Reduced to an Alkane? 5A Catalytic Cracking and the Importance of Alkenes 5.7 How Can an Acetylide Anion Be Used to Create a New Carbon–Carbon Bond? IN THIS CHAPTER, we begin our systematic study of organic reactions and their mecha- nisms. Reaction mechanisms are step-by-step descriptions of how reactions proceed and are one of the most important unifying concepts in organic chemistry. We use the reactions of alkenes as the vehicle to introduce this concept. 129 130 CHAPTER 5 Reactions of Alkenes and Alkynes 5.1 What Are the Characteristic Reactions of Alkenes? The most characteristic reaction of alkenes is addition to the carbon–carbon double bond in such a way that the pi bond is broken and, in its place, sigma bonds are formed to two new atoms or groups of atoms. Several examples of reactions at the carbon–carbon double bond are shown in Table 5.1, along with the descriptive name(s) associated with each.
    [Show full text]
  • Peroxides and Peroxide- Forming Compounds
    FEATURE Peroxides and peroxide- forming compounds By Donald E. Clark Bretherick5 included a discussion of nated. However, concentrated hydro- organic peroxide5 in a chapter on gen peroxide (Ͼ30%), in contact with norganic and organic peroxides, highly reactive and unstable com- ordinary combustible materials (e.g., because of their exceptional reac- pounds and used “oxygen balance” to fabric, oil, wood, or some resins) Itivity and oxidative potential are predict the stability of individual com- poses significant fire or explosion haz- widely used in research laboratories. pounds and to assess the hazard po- ards. Peroxides of alkali metals are not This review is intended to serve as a tential of an oxidative reaction. Jack- particularly shock sensitive, but can 6 guide to the hazards and safety issues son et al. addressed the use of decompose slowly in the presence of associated with the laboratory use, peroxidizable chemicals in the re- moisture and may react violently with handling, and storage of inorganic and search laboratory and published rec- a variety of substances, including wa- organic peroxy-compounds and per- ommendations for maximum storage ter. Thus, the standard iodide test for oxide-forming compounds. time for common peroxide-forming peroxides must not be used with these The relatively weak oxygen-oxygen laboratory solvents. Several solvents, water-reactive compounds.1 linkage (bond-dissociation energy of (e.g., diethyl ether) commonly used in Inorganic peroxides are used as ox- 20 to 50 kcal moleϪ1) is the character- the laboratory can form explosive re- idizing agents for digestion of organic istic structure of organic and inor- action products through a relatively samples and in the synthesis of or- ganic peroxide molecules, and is the slow oxidation process in the pres- ganic peroxides.
    [Show full text]
  • Radical Initiators
    Question #61073 – Chemistry – Organic Chemistry Question: List the various methods of generation of free radicals. Discuss in detail various redox sources of free radical generation. Answer: Methods of generation of free radicals Thermal Cracking At temperatures greater than 500º C, and in the absence of oxygen, mixtures of high molecular weight alkanes break down into smaller alkane and alkene fragments. This cracking process is important in the refining of crude petroleum because of the demand for lower boiling gasoline fractions. Free radicals, produced by homolysis of C–C bonds, are known to be intermediates in these transformations. Studies of model alkanes have shown that highly substituted C–C bonds undergo homolysis more readily than do unbranched alkanes. In practice, catalysts are used to lower effective cracking temperatures. Homolysis of Peroxides and Azo Compounds In contrast to stronger C–C and C–H bonds, the very weak O–O bonds of peroxides are cleaved at relatively low temperatures ( 80 to 150 ºC ), as shown in the following equations. The resulting oxy radicals may then initiate other reactions, or may decompose to carbon radicals, as noted in the shaded box. The most commonly used peroxide initiators are depicted in the first two equations. Organic azo compounds (R–N=N–R) are also heat sensitive, decomposing to alkyl radicals and nitrogen. Azobisisobutyronitrile (AIBN) is the most widely used radical initiator of this kind, decomposing slightly faster than benzoyl peroxide at 70 to 80 ºC. The thermodynamic stability of nitrogen provides an overall driving force for this decomposition, but its favorable rate undoubtedly reflects weaker than normal C-N bonds.
    [Show full text]
  • Table S1. GC-MS Compounds Generated at 5 °C/Min
    Table S1. GC-MS compounds generated at 5 °C/min. 0 wt.% 10 wt.% 30 wt.% 50 wt.% GC GC GC GC Compounds Compounds Compounds Compounds Area (%) Area (%) Area (%) Area (%) Time (min.) (min.) Time Time (min.) (min.) Time (min.) Time (min.) Time Propene Propene Propene Propene 7.42 7.42 1.26 5.47 1.20 7.38 1.200 1.200 1.200 1.214 1.214 1-Propene, 2- 1-Propene, 2- methyl- 1-Propene, 2-methyl- 1-Propene, 2-methyl- 7.34 7.34 2.41 methyl- 1.245 1.245 1.245 1.259 1.259 10.54 1.246 14.90 Pentane Pentane Pentane Pentane 3.79 3.79 1.375 1.375 1.395 1.395 11.81 1.381 13.17 1.375 12.83 1-Pentene, 2- 2-Butene, 2- 2-Butene, 2-methyl- 2-Butene, 2-methyl- methyl- 7.25 0.93 methyl- 4.65 5.71 1.426 1.426 1.420 1.420 1.679 1.679 1H-Pyrazole, 4,5- Heptane, 4- 1H-Pyrazole, 4,5- 1-Pentene, 2-methyl- dihydro-5- methyl- 1.92 1.57 2.25 dihydro-5-methyl- 2.44 1.659 1.659 1.562 1.569 3.762 3.762 methyl- 2,4-Dimethyl-1- 1-Pentene, 2- heptene 2-Butene, 2,3-dimethyl- 1-Pentene, 2-methyl- 1.27 1.27 methyl- 3.08 2.33 1.653 1.653 1.653 5.671 5.671 34.57 1.750 Cyclohexane, 1,3,5-trimethyl-, 2-Pentene, 3- 2,4-Dimethyl-1-heptene 2-Pentene, 2-methyl- alpha.,3.alpha.,5.b 2.03 9.11 methyl-, €- 6.11 5.73 5.605 5.605 1.743 1.744 5.981 5.981 eta.)- 5-Aminoisoxazole 2-Pentene, 3- 2-Pentene, 3-methyl-, Spermine Ethanone, 1-cyclopentyl- 1.55 1.55 1.32 methyl-, (Z)- 1.59 €- 1.46 1.828 1.828 1.828 6.925 6.925 10.560 Ethanone, 1- 1R,2c,3t,4t-Tetramethyl- 1,3-Pentadiene, 1,4-Hexadiene, 5- cyclopentyl- 3.57 3.57 cyclohexan 0.97 2,3-dimethyl- 2.28 methyl- 2.31 2.584 2.584 2.585 10.613 10.613 10.638 N- Heptane, 2-methyl-3- Heptane, 4- Methylallylamine Toluene 2.49 2.49 methylene- 2.50 methyl- 2.97 4.31 3.697 3.697 3.697 14.047 14.047 10.684 10.684 2-Undecene, 4- Cyclopentane, (2- 2,4-Dimethyl-1- 2,4-Dimethyl-1- methyl- 7.81 7.81 methylbutyl)- 1.00 heptene heptene 5.605 5.605 22.29 22.29 5.605 12.95 14.086 14.086 14.163 Cyclohexane, Cyclohexane, 1,3,5- 2-Decene, 7- 1,3,5-trimethyl-, trimethyl- methyl-, (Z)- Hexane, 2,3,4-trimethyl- (1.
    [Show full text]
  • Gfsorganics & Fragrances
    Chemicals for Flavors GFSOrganics & Fragrances GFS offers a broad range of specialty organic chemicals Specialized chemistries we as building blocks and intermediates for the manufacture of offer include: flavors and fragrances. • Alkynes Over 5,500 materials, including 1,400 chemicals from natural sources, are used for flavor • Alkynols enhancements and aroma profiles. These aroma chemicals are integral components of • Olefins the continued growth within consumer products and packaged foods. The diversity of products can be attributed to the broad spectrum of organic compounds derived from • Unsaturated Acids esters, aldehydes, lactones, alcohols and several other functional groups. • Unsaturated Esters • DIPPN and other Products GFS Chemicals manufactures a wide range of organic intermediates that have been utilized in a multitude of personal care applications. For example, we support Why GFS? several market leading companies in the manufacture and supply of alkyne based aroma chemicals. • Specialized Chemistries • Tailored Specifications As such, we understand the demanding nature of this fast changing market and are fully • From Grams to Metric Tons equipped to overcome process challenges and manufacture the novel chemical products • Responsive Technical Staff that you need, when you need them. We offer flexible custom manufacturing services to produce high purity products with the assurance of quality and full confidentiality. • Uncompromised Product Quality Our state-of-the-art manufacturing facility, located in Columbus, OH is ISO 9001:2008 certified. As a U.S. based manufacturer we have a proven record of helping you take products from development to commercialization. Our technical sales experts are readily accessible to discuss your project needs and unique product specifications.
    [Show full text]
  • Ionic Liquid*
    Pure Appl. Chem., Vol. 83, No. 7, pp. 1391–1406, 2011. doi:10.1351/PAC-CON-10-12-03 © 2011 IUPAC, Publication date (Web): 10 June 2011 Oligomerisation of linear 1-olefins using a chlorogallate(III) ionic liquid* Martin P. Atkins1, Kenneth R. Seddon2,‡, and Małgorzata Swadźba-Kwaśny2,‡ 1PETRONAS Research Sdn Bhd, Lot 3288&3289, Off Jalan Ayer Itam, Kawasan Institusi Bangi, 43000, Kajang, Malaysia; 2QUILL, The Queen’s University of Belfast, Belfast, BT9 5AG, UK Abstract: A Lewis acidic chlorogallate(III) ionic liquid, 1-ethyl-3-methylimidazolium hepta - chlorodigallate(III), [C2mim][Ga2Cl7], was successfully used to oligomerise 1-pentene. The influence of temperature, time, catalyst concentration, and stirring rate on conversion and product distribution was modelled using a design of experiment (DoE) approach (chemo - metrics). The process was optimised for lubricant base oils production; the C20–C50 fraction (where Cn indicates the number of carbons in the oligomer) was maximised, while the heav- ier oligomer fraction (>C50) was minimised. Keywords: 1-alkenes; chemometrics; ionic liquids; linear terminal olefins; 1-olefins; oligomerisation. INTRODUCTION Oligomerisation and ionic liquids Polyalphaolefins (PAOs), used as a base for synthetic automotive lubricants (Group 4 base stock by API classification) [1], are traditionally made by oligomerisation of 1-decene to C20–C50 blend (where Cn indicates the number of carbons in the oligomer) [2] using Ziegler–Natta or Friedel–Crafts catalysts [3]. The carbon number is important, as the pour point of higher polymers (>C50) is too high, whilst the lower cut (<C20) is too volatile. 1-Decene is manufactured in a very selective manner from ethene [2].
    [Show full text]
  • Steam Cracking: Chemical Engineering
    Steam Cracking: Kinetics and Feed Characterisation João Pedro Vilhena de Freitas Moreira Thesis to obtain the Master of Science Degree in Chemical Engineering Supervisors: Professor Doctor Henrique Aníbal Santos de Matos Doctor Štepánˇ Špatenka Examination Committee Chairperson: Professor Doctor Carlos Manuel Faria de Barros Henriques Supervisor: Professor Doctor Henrique Aníbal Santos de Matos Member of the Committee: Specialist Engineer André Alexandre Bravo Ferreira Vilelas November 2015 ii The roots of education are bitter, but the fruit is sweet. – Aristotle All I am I owe to my mother. – George Washington iii iv Acknowledgments To begin with, my deepest thanks to Professor Carla Pinheiro, Professor Henrique Matos and Pro- fessor Costas Pantelides for allowing me to take this internship at Process Systems Enterprise Ltd., London, a seven-month truly worthy experience for both my professional and personal life which I will certainly never forget. I would also like to thank my PSE and IST supervisors, who help me to go through this final journey as a Chemical Engineering student. To Stˇ epˇ an´ and Sreekumar from PSE, thank you so much for your patience, for helping and encouraging me to always keep a positive attitude, even when harder problems arose. To Prof. Henrique who always showed availability to answer my questions and to meet in person whenever possible. Gostaria tambem´ de agradecer aos meus colegas de casa e de curso Andre,´ Frederico, Joana e Miguel, com quem partilhei casa. Foi uma experienciaˆ inesquec´ıvel que atravessamos´ juntos e cer- tamente que a vossa presenc¸a diaria´ apos´ cada dia de trabalho ajudou imenso a aliviar as saudades de casa.
    [Show full text]