DOCSLIB.ORG

Christopher Ingold's Insights Into Mechanism and Reactivity

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Christopher Ingold's Insights Into Mechanism and Reactivity Historical profile Organic pioneer Christopher Ingold’s insights into mechanism and reactivity established many of the principles of organic chemistry. John Ridd reveals more about his life and work ROYAL SOCIETY OF CHEMISTRY / LIBRARY AND INFORMATION CENTRE INFORMATION AND LIBRARY / CHEMISTRY OF SOCIETY ROYAL 50 | Chemistry World | December 2008 www.chemistryworld.org Sir Christopher Ingold in Glasgow on the preparation of During those years, there was In short fundamentally changed the gases for use in chemical warfare. another important, more personal approach of chemists to organic This was dangerous work for which Christopher Ingold development in Ingold’s life. In 1922 chemistry. Many have forgotten Ingold was awarded the British established some he published a paper with Edith what a strange and mysterious Empire Medal. He subsequently of the fundamental Hilda Usherwood on the specific subject organic chemistry appeared made no reference to the award or to mechanisms of organic heats of gases and, a year later, they to be in the days before reaction his work during the war. chemistry were married. His wife was herself mechanisms were revealed. Organic Possibly his most a talented chemist but, after a few chemistry is now viewed in a very Award-winning chemistry important work was years, she gave up her research and different way – based on firmly In 1920 Ingold returned to Imperial on the mechanism of supported her husband’s scientific established mechanistic principles College as a demonstrator with his substitution reactions career. – and, although many people have own research laboratory. It was the He described, for At Leeds, Ingold’s interests rapidly contributed to that change, almost beginning of a remarkably active the first time, the two turned to the nature of chemical all chemists would now accept that period of research: he published 12 different forms of bonding. Robert Robinson, who was Ingold was the predominant figure. papers in 1921, 16 papers in 1922, and nucleophilic substitution, then a professor at the University Although this account focuses on his 14 papers in 1923. Most of these dealt SN1 and SN2 of Manchester, UK, had recognised work in organic chemistry, Ingold with classical organic chemistry, His organic chemistry that the current discussions, in terms also made important contributions and some with physical chemistry, textbook soon became an of partial valency and chemical to spectroscopy and inorganic including specific heats and vapour essential reference affinity, lacked any common physical chemistry. pressures. basis and suggested that this could Ingold was born in London on Ingold’s impressive publication be found in the electronic theories 28 October 1893. His father, a silk record led to rapid movement up the of valency put forward by Thomson, merchant, was in very poor health academic ladder – he was promoted Lewis and Langmuir. with tuberculosis; it was for this to a lectureship, gained a DSc (doctor In his 1922 paper, Robinson used reason that the family moved to of science) degree and was awarded Arthur Lapworth’s description of the supposedly gentler climate of the first Meldola Medal in 1922 – an reagents as ‘kationoid’ and ‘anionoid’ Shanklin in the Isle of Wight. But award to commemorate Raphael but added what we would in modern his father died when Ingold was five Meldola, who was president of both terms call inductive and conjugative years old. the Society of Maccabaeans and electron shifts. There are even two After studying at the local school the Royal Institute of Chemistry. of the now common curly arrows to in Shanklin, Ingold moved to the new Remarkably, he was also awarded represent the movement of electrons secondary school at Sandown where a second Meldola Medal in 1923, in a conjugated system. he obtained a county scholarship to and was the only person ever to In his paper on tautomerism study at the new Hartley University receive two medals (the rules were in 1926, Ingold also interpreted College in Southampton. After subsequently changed to make it the results in terms of electron obtaining his BSc degree there, he impossible for an applicant to receive Ingold, Hughes and movements, this time making moved to Imperial College London more than one). In 1924, he was Ingold’s wife Hilda at extensive use of curly arrows. The and, in 1914, joined the research elected to fellowship of the Royal a UCL dinner marking paper contains one reference to group of Jocelyn Thorpe, a new Society and accepted the position Ingold’s receipt of the Robinson’s work published in the professor of organic chemistry. In of professor of chemistry at Leeds Longstaff medal from the same year, but was the start of the 1915, he was asked to carry out work University, UK. Chemical Society long-standing controversy between www.chemistryworld.org Chemistry World | December 2008 | 51 Historical profile Robinson and Ingold – Robinson and substituent effects. Robinson’s considered that insufficient bitterness over the way in which recognition had been given to his his presentation of the electronic earlier ideas. theory was supplanted by that of Ingold continued for the rest of his Opposing conventions life. In his autobiography, Robinson Ingold continued to develop the maintained that the electronic theory of electronic effects in theory was his most important organic chemistry, making a clear contribution to knowledge. distinction between polarisation and In August of 1930, Ingold moved polarisability effects and introducing from Leeds to a professorship at the concept of mesomerism University College London and – equivalent to the concept of remained there until his death 40 resonance between valence bond years later. In the same year, he ROYAL SOCIETY OF CHEMISTRY / LIBRARY AND INFORMATION CENTRE INFORMATION AND LIBRARY / CHEMISTRY OF SOCIETY ROYAL structures – as the permanent was joined by Ted Hughes, a young consequence of tautomeric electron postdoctoral worker who had just displacements in a molecule before taken his PhD with H B Watson at a reaction. Bangor. This was the start of a long Ingold’s terminology differs from collaboration which lasted until that of Robinson, and this is also Hughes’s death 33 years later. true of his description of reagents After arriving at University – Ingold used the terms electrophilic College, Ingold began kinetic and nucleophilic in place of and mechanistic studies. As with kationoid and anionoid on the basis his studies of substituent effects, that whether a reagent is electron- Ingold introduced a language attracting or electron-repelling is for mechanistic studies which not simply dependent on its charge. eventually became accepted. He The two scientists also disagreed first grouped organic reactions on the sign to be attached to according to the underlying substituent effects. Ingold electronic processes involved. Thus designated the effects of electron- the reactions of hydroxide ions and donating substituents as positive To write up their results, they had Sir Robert Robinson amines with alkyl halides together and those of electron-withdrawing to choose one or the other, and quite (above) was bitter that with the reactions of amines with substituents as negative. Shortly quickly Ingold’s approach became his electronic theory was alkyl ammonium ions were termed afterwards Robinson proposed the one generally accepted. One supplanted by Ingold’s ‘nucleophilic substitution at a the opposite sign convention. reason for the preference may have saturated carbon atom’ because, Ingold’s ideas were set out in his been that more people read Ingold’s although the reactions appear article in Chemical Reviews in article in Chemical Reviews than very different in the reagents and 1934 and Robinson set out his own read the reprints of Robinson’s charges, they all involve the attack alternative system in two lectures lectures at the Royal Institute of of a nucleophile and the departure published together by the Institute Chemistry. But perhaps the main of a leaving group with the bonding of Chemistry in 1932. reason is that much of Robinson’s electrons. So, in the early 1930s, chemists interest moved from electronic Ingold made a further distinction were faced with two versions of theories to what he considered by investigating the kinetics of an electronic theory of organic to be other major challenges these nucleophilic substitutions. chemistry with many similar – particularly biosynthesis – while He found two basic forms: in one, features but using a quite different Ingold maintained a rapid rate of the rate of the reaction depended terminology and sign convention. publication in the area of mechanism on the concentration of both the nucleophile and the organic molecule it was attacking. In the Substitution mechanisms other, however, increasing the Ingold described, for the first time, the two where a nucleophile attacks and a leaving group concentration of the nucleophile different forms of nucleophilic substitution SN1 departs simultaneously, always inverts the 3D made no difference to the reaction and SN2. arrangement of atoms neighbouring the reaction rate, which only depended on the This mechanistic distinction has an centre – rather like an umbrella turning inside out. concentration of organic substrate. important bearing on the stereochemistry of The SN1 reaction, however, can either invert or As Ingold worked out, that was the substitution. In two series of papers, Ingold retain the starting arrangement, since the planar because in the first kinetic
Load more

Recommended publications
  • Reactions of Benzene & Its Derivatives
    Organic Lecture Series ReactionsReactions ofof BenzeneBenzene && ItsIts DerivativesDerivatives Chapter 22 1 Organic Lecture Series Reactions of Benzene The most characteristic reaction of aromatic compounds is substitution at a ring carbon: Halogenation: FeCl3 H + Cl2 Cl + HCl Chlorobenzene Nitration: H2 SO4 HNO+ HNO3 2 + H2 O Nitrobenzene 2 Organic Lecture Series Reactions of Benzene Sulfonation: H 2 SO4 HSO+ SO3 3 H Benzenesulfonic acid Alkylation: AlX3 H + RX R + HX An alkylbenzene Acylation: O O AlX H + RCX 3 CR + HX An acylbenzene 3 Organic Lecture Series Carbon-Carbon Bond Formations: R RCl AlCl3 Arenes Alkylbenzenes 4 Organic Lecture Series Electrophilic Aromatic Substitution • Electrophilic aromatic substitution: a reaction in which a hydrogen atom of an aromatic ring is replaced by an electrophile H E + + + E + H • In this section: – several common types of electrophiles – how each is generated – the mechanism by which each replaces hydrogen 5 Organic Lecture Series EAS: General Mechanism • A general mechanism slow, rate + determining H Step 1: H + E+ E El e ctro - Resonance-stabilized phile cation intermediate + H fast Step 2: E + H+ E • Key question: What is the electrophile and how is it generated? 6 Organic Lecture Series + + 7 Organic Lecture Series Chlorination Step 1: formation of a chloronium ion Cl Cl + + - - Cl Cl+ Fe Cl Cl Cl Fe Cl Cl Fe Cl4 Cl Cl Chlorine Ferric chloride A molecular complex An ion pair (a Lewis (a Lewis with a positive charge containing a base) acid) on ch lorine ch loronium ion Step 2: attack of
    [Show full text]
  • Reactions of Aromatic Compounds Just Like an Alkene, Benzene Has Clouds of  Electrons Above and Below Its Sigma Bond Framework
    Reactions of Aromatic Compounds Just like an alkene, benzene has clouds of electrons above and below its sigma bond framework. Although the electrons are in a stable aromatic system, they are still available for reaction with strong electrophiles. This generates a carbocation which is resonance stabilized (but not aromatic). This cation is called a sigma complex because the electrophile is joined to the benzene ring through a new sigma bond. The sigma complex (also called an arenium ion) is not aromatic since it contains an sp3 carbon (which disrupts the required loop of p orbitals). Ch17 Reactions of Aromatic Compounds (landscape).docx Page1 The loss of aromaticity required to form the sigma complex explains the highly endothermic nature of the first step. (That is why we require strong electrophiles for reaction). The sigma complex wishes to regain its aromaticity, and it may do so by either a reversal of the first step (i.e. regenerate the starting material) or by loss of the proton on the sp3 carbon (leading to a substitution product). When a reaction proceeds this way, it is electrophilic aromatic substitution. There are a wide variety of electrophiles that can be introduced into a benzene ring in this way, and so electrophilic aromatic substitution is a very important method for the synthesis of substituted aromatic compounds. Ch17 Reactions of Aromatic Compounds (landscape).docx Page2 Bromination of Benzene Bromination follows the same general mechanism for the electrophilic aromatic substitution (EAS). Bromine itself is not electrophilic enough to react with benzene. But the addition of a strong Lewis acid (electron pair acceptor), such as FeBr3, catalyses the reaction, and leads to the substitution product.
    [Show full text]
  • AROMATIC NUCLEOPHILIC SUBSTITUTION-PART -2 Electrophilic Substitution
    Dr. Tripti Gangwar AROMATIC NUCLEOPHILIC SUBSTITUTION-PART -2 Electrophilic substitution ◦ The aromatic ring acts as a nucleophile, and attacks an added electrophile E+ ◦ An electron-deficient carbocation intermediate is formed (the rate- determining step) which is then deprotonated to restore aromaticity ◦ electron-donating groups on the aromatic ring (such as -OH, -OCH3, and alkyl) make the reaction faster, since they help to stabilize the electron-poor carbocation intermediate ◦ Lewis acids can make electrophiles even more electron-poor (reactive), increasing the reaction rate. For example FeBr3 / Br2 allows bromination to occur at a useful rate on benzene, whereas Br2 by itself is slow). In fact, a substitution reaction does occur! (But, as you may suspect, this isn’t an electrophilic aromatic substitution reaction.) In this substitution reaction the C-Cl bond breaks, and a C-O bond forms on the same carbon. The species that attacks the ring is a nucleophile, not an electrophile The aromatic ring is electron-poor (electrophilic), not electron rich (nucleophilic) The “leaving group” is chlorine, not H+ The position where the nucleophile attacks is determined by where the leaving group is, not by electronic and steric factors (i.e. no mix of ortho– and para- products as with electrophilic aromatic substitution). In short, the roles of the aromatic ring and attacking species are reversed! The attacking species (CH3O–) is the nucleophile, and the ring is the electrophile. Since the nucleophile is the attacking species, this type of reaction has come to be known as nucleophilic aromatic substitution. n nucleophilic aromatic substitution (NAS), all the trends you learned in electrophilic aromatic substitution operate, but in reverse.
    [Show full text]
  • 19.1 Ketones and Aldehydes
    19.1 Ketones and Aldehydes • Both functional groups possess the carbonyl group • Important in both biology and industry Simplest aldehyde Simplest ketone used as a used mainly as preservative a solvent Copyright © 2017 John Wiley & Sons, Inc. All rights reserved. 19-1 Klein, Organic Chemistry 3e 19.1 Ketones And Aldehydes Copyright © 2017 John Wiley & Sons, Inc. All rights reserved. 19-2 Klein, Organic Chemistry 3e 19.2 Nomenclature • Four discrete steps to naming an aldehyde or ketone • Same procedure as with alkanes, alcohols, etc… 1. Identify and name the parent chain 2. Identify the name of the substituents (side groups) 3. Assign a locant (number) to each substituents 4. Assemble the name alphabetically Copyright © 2017 John Wiley & Sons, Inc. All rights reserved. 19-3 Klein, Organic Chemistry 3e 19.2 Nomenclature 1. Identify and name the parent chain – For aldehydes, replace the “-e” ending with an “-al” – the parent chain must include the carbonyl carbon Copyright © 2017 John Wiley & Sons, Inc. All rights reserved. 19-4 Klein, Organic Chemistry 3e 19.2 Nomenclature 1. Identify and name the parent chain – The aldehydic carbon is assigned number 1: Copyright © 2017 John Wiley & Sons, Inc. All rights reserved. 19-5 Klein, Organic Chemistry 3e 19.2 Nomenclature 1. Identify and name the parent chain – For ketones, replace the “-e” ending with an “-one” – The parent chain must include the C=O group – the C=O carbon is given the lowest #, and can be expressed before the parent name or before the suffix Copyright © 2017 John Wiley & Sons, Inc. All rights reserved.
    [Show full text]
  • Aromatic Nucleophilic Substitution Reaction
    Aromatic Nucleophilic Substitution Reaction DR. RAJENDRA R TAYADE ASSISTANT PROFESSOR DEPARTMENT OF CHEMISTRY INSTITUTE OF SCIENCE, NAGPUR Principles There are four principal mechanisms for aromatic nucleophilic substitution which are similar to that of aliphatic nucleophilic substitution. (SN1, SN2, SNi, SET Mechanism) 1. SNAr Mechanism- addition / elimination CF3, CN, CHO, COR, COOH, Br, Cl, I Common Activating Groups for NAS Step [1] Addition of the nucleophile (:Nu–) to form a carbanion Addition of the nucleophile (:Nu–) forms a resonance-stabilized carbanion with a new C – Nu bond— three resonance structures can be drawn. • Step is rate-determining • Aromaticity of the benzene ring is lost Step [2] loss of the leaving group re-forms the aromatic ring. • This step is fast because the aromaticity of the benzene ring is restored. ? Explain why a methoxy group (CH3O) increases the rate of electrophilic aromatic substitution, but decreases the rate of nucleophilic aromatic substitution. 2.ArSN1 Mechanism- elimination /addition • This mechanism operates in the reaction of diazonium salts with nucleophiles. •The driving force resides in the strength of the bonding in the nitrogen molecule that makes it a particularly good leaving group. 3.Benzyne Mechanism- elimination /addition Step [1] Elimination of HX to form benzyne Elimination of H and X from two adjacent carbons forms a reactive benzyne intermediate Step [2] Nucleophilic addition to form the substitution product Addition of the nucleophile (–OH in this case) and protonation form the substitution product Evidence for the Benzyne Mechanism Trapping in Diels/Alder Reaction O O B E N Z Y N E C C O O O D i e l s / A l d e r O N H 3 N N Dienophile Diene A d d u c t Substrate Modification – absence of a hydrogens LG Substituent Substituent No Reaction Base Isotopic Labeling LG Nu H Nu Structure of Benzyne • The σ bond is formed by overlap of two sp2 hybrid orbitals.
    [Show full text]
  • A Marcus-Theory-Based Approach to Ambident Reactivity
    Dissertation zur Erlangung des Doktorgrades der Fakultät für Chemie und Pharmazie der Ludwig-Maximilians-Universität München A Marcus-Theory-Based Approach to Ambident Reactivity Robert Martin Breugst aus München 2010 Erklärung Diese Dissertation wurde im Sinne von § 13 Abs. 3 bzw. 4 der Promotionsordnung vom 29. Januar 1998 (in der Fassung der vierten Änderungssatzung vom 26. November 2004) von Herrn Professor Dr. Herbert Mayr betreut. Ehrenwörtliche Versicherung Diese Dissertation wurde selbständig, ohne unerlaubte Hilfe erarbeitet. München, 28.10.2010 _________________________ Dissertation eingereicht am: 28.10.2010 1. Gutachter: Prof. Dr. Herbert Mayr 2. Gutachter: Prof. Dr. Hendrik Zipse Mündliche Prüfung am: 21.12.2010 II Acknowledgements Acknowledgements First of all, I would like to express my cordial gratitude to Professor Dr. Herbert Mayr for the opportunity to compose this thesis in his group. I have cherished all the valuable discussions with him, his endless support, and his inspiring confidence very much and I have always appreciated working under these excellent conditions. From the very first day in his group Professor Mayr made me feel welcome, has always been willing to discuss my ideas, and encouraged me to pursue a scientific career. Furthermore, I would like to thank Professor Dr. Hendrik Zipse for numerous discussions and helpful comments on quantum chemical calculations, and of course also for reviewing my thesis. Additionally, I am very indebted to Professor J. Peter Guthrie, Ph.D., for giving me the opportunity to spend almost 4 months in his group at the University of Western Ontario. During this time, I have learned so many new things and I am grateful for the reams of discussions in his office.
    [Show full text]
  • Effect of Nucleophile on Reaction
    1 Effect of nucleophile on reaction H H H H H H H RDS H H RDS + Nuc R H Nuc X R X R Nuc R X Nuc R X • Nucleophile not involved in RDS of SN1 so does not effect the reaction (well obviously it controls the formula of the product!) • Nucleophile has a big effect on SN2 • Large nucleophiles are poor in SN2 reactions due to steric hindrance Large nucleophile (t-BuOH) suffers steric interactions Small nucleophile (MeOH) can easily approach 2 Nucleophile strength • The stronger the nucleophile the faster / more efficient the SN2 reaction • Nucleophilic strength (nucleophilicity) relates to how easily a compound can donate an electron pair • The more electronegative an atom the less nucleophilic as the electrons are held closer nucleophilic strength Anion more nucleophilic H O than its neutral analogue (basicity) HO > 2 nucleophilic strength R C (basicity) 3 > R2N > RO > F As we move along a row the electronegativity electronegativity C < N < O < F increases and nucleophilic strength nucleophilicity decreases (basicity) R NH2 > R OH > R F As we go down a group both anions and neutral atoms get more nucleophilic strength H2S > H2O (basicity) nucleophilic - electrons I > Br > Cl > F not held as tightly as size increases 3 Solvent effects SN1 • Intermediate - the carbocation - is stabilised by polar solvents • Leaving group stabilised by protic solvents (encourages dissociation) • Water, alcohols & carboxylic acids good solvents for SN1 Br H O H O H H Br O H O H O cation hydrogen stabilised O bonds SN2 • Prefer less polar, aprotic solvents • Less
    [Show full text]
  • Reactions of Alkenes Since  Bonds Are Stronger Than  Bonds, Double Bonds Tend to React to Convert the Double Bond Into  Bonds
    Reactions of Alkenes Since bonds are stronger than bonds, double bonds tend to react to convert the double bond into bonds This is an addition reaction. (Other types of reaction have been substitution and elimination). Addition reactions are typically exothermic. Electrophilic Addition The bond is localized above and below the C-C bond. The electrons are relatively far away from the nuclei and are therefore loosely bound. An electrophile will attract those electrons, and can pull them away to form a new bond. This leaves one carbon with only 3 bonds and a +ve charge (carbocation). The double bond acts as a nucleophile (attacks the electrophile). Ch08 Reacns of Alkenes (landscape) Page 1 In most cases, the cation produced will react with another nucleophile to produce the final overall electrophilic addition product. Electrophilic addition is probably the most common reaction of alkenes. Consider the electrophilic addition of H-Br to but-2-ene: The alkene abstracts a proton from the HBr, and a carbocation and bromide ion are generated. The bromide ion quickly attacks the cationic center and yields the final product. In the final product, H-Br has been added across the double bond. Ch08 Reacns of Alkenes (landscape) Page 2 Orientation of Addition Consider the addition of H-Br to 2-methylbut-2-ene: There are two possible products arising from the two different ways of adding H-Br across the double bond. But only one is observed. The observed product is the one resulting from the more stable carbocation intermediate. Tertiary carbocations are more stable than secondary.
    [Show full text]
  • Chapter 11: Nucleophilic Substitution and Elimination Walden Inversion
    Chapter 11: Nucleophilic Substitution and Elimination Walden Inversion O O PCl5 HO HO OH OH O OH O Cl (S)-(-) Malic acid (+)-2-Chlorosuccinic acid [a]D= -2.3 ° Ag2O, H2O Ag2O, H2O O O HO PCl5 OH HO OH O OH O Cl (R)-(+) Malic acid (-)-2-Chlorosuccinic acid [a]D= +2.3 ° The displacement of a leaving group in a nucleophilic substitution reaction has a defined stereochemistry Stereochemistry of nucleophilic substitution p-toluenesulfonate ester (tosylate): converts an alcohol into a leaving group; tosylate are excellent leaving groups. abbreviates as Tos C X Nu C + X- Nu: X= Cl, Br, I O Cl S O O + C OH C O S CH3 O CH3 tosylate O -O S O O Nu C + Nu: C O S CH3 O CH3 1 O Tos-Cl - H3C O O H + TosO - H O H pyridine H O Tos O CH3 [a]D= +33.0 [a]D= +31.1 [a]D= -7.06 HO- HO- O - Tos-Cl H3C O - H O O TosO + H O H pyridine Tos H O CH3 [a]D= -7.0 [a]D= -31.0 [a]D= -33.2 The nucleophilic substitution reaction “inverts” the Stereochemistry of the carbon (electrophile)- Walden inversion Kinetics of nucleophilic substitution Reaction rate: how fast (or slow) reactants are converted into product (kinetics) Reaction rates are dependent upon the concentration of the reactants. (reactions rely on molecular collisions) H H Consider: HO C _ _ C Br Br HO H H H H At a given temperature: If [OH-] is doubled, then the reaction rate may be doubled If [CH3-Br] is doubled, then the reaction rate may be doubled A linear dependence of rate on the concentration of two reactants is called a second-order reaction (molecularity) 2 H H HO C _ _ C Br Br HO H H H H Reaction rates (kinetic) can be expressed mathematically: reaction rate = disappearance of reactants (or appearance of products) For the disappearance of reactants: - rate = k [CH3Br] [OH ] [CH3Br] = CH3Br concentration [OH-] = OH- concentration k= constant (rate constant) L mol•sec For the reaction above, product formation involves a collision between both reactants, thus the rate of the reaction is dependent upon the concentration of both.
    [Show full text]
  • Activation of Alcohols Toward Nucleophilic Substitution: Conversion of Alcohols to Alkyl Halides Amani Atiyalla Abdugadar
    University of Northern Colorado Scholarship & Creative Works @ Digital UNC Theses Student Research 12-1-2012 Activation of Alcohols Toward Nucleophilic Substitution: Conversion of Alcohols to Alkyl Halides Amani Atiyalla Abdugadar Follow this and additional works at: http://digscholarship.unco.edu/theses Recommended Citation Abdugadar, Amani Atiyalla, "Activation of Alcohols Toward Nucleophilic Substitution: Conversion of Alcohols to Alkyl Halides" (2012). Theses. Paper 22. This Text is brought to you for free and open access by the Student Research at Scholarship & Creative Works @ Digital UNC. It has been accepted for inclusion in Theses by an authorized administrator of Scholarship & Creative Works @ Digital UNC. For more information, please contact [email protected]. © 2012 Amani Abdugadar ALL RIGHTS RESERVED UNIVERSITY OF NORTHERN COLORADO Greeley, Colorado The Graduate School ACTIVATION OF ALCOHOLS TOWARD NEOCLEOPHILIC SUBSTITUTION: CONVERSION OF ALCOHOLS TO ALKYL HALIDES A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science Amani Abdugadar College of Natural and Health Sciences Department of Chemistry and Biochemistry December, 2012 This Thesis by: Amani Abdugadar Entitled: Activation of Alcohols Toward Neocleophilic Substitution: Conversion of Alcohols to Alkyl Halides has been approved as meeting the requirement for the Master of Science in College of Natural and Health Sciences in Department of Chemistry and Biochemistry Accepted by the Thesis Committee ______________________________________________________ Michael D. Mosher, Ph.D., Research Co-Advisor ______________________________________________________ Richard W. Schwenz, Ph.D., Research Co-Advisor ______________________________________________________ David L. Pringle, Ph.D., Committee Member Accepted by the Graduate School _________________________________________________________ Linda L. Black, Ed.D., LPC Acting Dean of the Graduate School and International Admissions ABSTRACT Abdugadar, Amani.
    [Show full text]
  • Pyridine System: the Local Hard and Soft Acids and Bases Principle Perspective Journal of the Mexican Chemical Society, Vol
    Journal of the Mexican Chemical Society ISSN: 1870-249X [email protected] Sociedad Química de México México Richaud, Arlette; Méndez, Francisco Nucleophilic Attack at the Pyridine Nitrogen Atom in a Bis(imino)pyridine System: The Local Hard and Soft Acids and Bases Principle Perspective Journal of the Mexican Chemical Society, vol. 56, núm. 3, julio-septiembre, 2012, pp. 351-354 Sociedad Química de México Distrito Federal, México Available in: http://www.redalyc.org/articulo.oa?id=47524533019 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative J. Mex. Chem. Soc. 2012, 56(3), 351-354 ArticleNucleophilic Attack at the Pyridine Nitrogen Atom in a Bis(imino)pyridine System: The Local Hard and© Soft 2012, Acids Sociedad and Bases Química de México351 ISSN 1870-249X Nucleophilic Attack at the Pyridine Nitrogen Atom in a Bis(imino)pyridine System: The Local Hard and Soft Acids and Bases Principle Perspective Arlette Richaud and Francisco Méndez* Departamento de Química, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, A.P. 55-534, México, D.F., 09340 México. Dedicated to José Luis Gázquez Received January 06, 2012; accepted June 04, 2012 Abstract. Motivated by the unprecedented nucleophilic attack at the Resumen. Motivados por el ataque nucleofílico sin precedentes sobre pyridine nitrogen atom in bis(imino)pyridines, observed by Gambaro- el átomo de nitrógeno de la piridina en bis(imino)piridinas observado tta et al.
    [Show full text]
  • Nucleophilic Addition to the Carbonyl Group 6
    Nucleophilic addition to the carbonyl group 6 Connections Building on Arriving at Looking forward to • Functional groups, especially the C=O • How and why the C=O group reacts • Additions of organometallic group ch2 with nucleophiles reagents ch9 • Identifying the functional groups in a • Explaining the reactivity of the C=O • Substitution reactions of the C=O molecule spectroscopically ch3 group using molecular orbitals and curly group’s oxygen atom ch11 • How molecular orbitals explain arrows • How the C=O group in derivatives of molecular shapes and functional • What sorts of molecules can be made by carboxylic acids promotes substitution groups ch4 reactions of C=O groups reactions ch10 • How, and why, molecules react together • How acid or base catalysts improve the • C=O groups with an adjacent double and using curly arrows to describe reactivity of the C=O group bond ch22 reactions ch5 Molecular orbitals explain the reactivity of the carbonyl group We are now going to leave to one side most of the reactions you met in the last chapter—we will come back to them all again later in the book. In this chapter we are going to concentrate on just one of them—probably the simplest of all organic reactions—the addition of a nucleo- phile to a carbonyl group. The carbonyl group, as found in aldehydes, ketones, and many other compounds, is without doubt the most important functional group in organic chemis- try, and that is another reason why we have chosen it as our fi rst topic for more detailed study. You met nucleophilic addition to a carbonyl group on pp.
    [Show full text]