DOCSLIB.ORG

Organometallic Compoundscompounds (Chapter 15)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Organometallic Compoundscompounds (Chapter 15) Organic Lecture Series OrganometallicOrganometallic CompoundsCompounds (Chapter 15) 1 Organic Lecture Series Organometallic compound • Organometallic compound: a compound that contains a carbon-metal bond • The focus will be on organometallic compounds of Mg, Li, and Cu – these classes illustrate the usefulness of organometallics in modern synthetic organic chemistry – the use of organometallics can bring about transformations that cannot be accomplished in any other way 2 Organic Lecture Series Organometallic reagents have 2 general types of reactions: 1. As Strong bases (Bronsted-Lowry) 2. As nucleophilic reagents. Regard the alkyl group as “R-” 3 Organic Lecture Series Grignard Reagents • Grignard reagent: an organomagnesium compound – prepared by addition of an alkyl, aryl, or alkenyl (vinylic) halide to Mg metal in diethyl ether or THF 4 Organic Lecture Series Preparation of Grignard reagents: ether Br + Mg MgBr 1-Bromobutane Butylmagnesium bromide (an alkyl Grignard reagent) ether Br+ Mg MgBr Bromobenzene Phenylmagnesium bromide (an aryl Grignard reagent) 5 Organic Lecture Series • Grignard reagents dissolve as coordination compounds solvated by ether – ethylmagnesium bromide, EtMgBr 6 Organic Lecture Series Organolithium reagents • Organolithium reagents – prepared by reaction of an alkyl, aryl, or alkenyl halide with lithium metal pentane Cl + 2LiLi + LiCl 1-Chlorobutane Butyllithium 7 Organic Lecture Series The carbon-metal bonds in RMgX and RLi are polar covalent C-M Difference in Percent Ionic Bond Electronegativity character* C-Li 2.5 - 1.0 = 1.5 60 Increasing Ionic C-Mg 2.5 - 1.2 = 1.3 52 Character C-Al 2.5 - 1.5 = 1.0 40 C-Zn 2.5 - 1.6 = 0.9 36 C-Sn 2.5 - 1.8 = 0.7 28 Stronger C-Cu 2.5 - 1.9 = 0.6 24 Nucleophile C-Hg 2.5 - 1.9 = 0.6 24 EC -EM *Percent ionic character = x 100 EC 8 Organic Lecture Series • Reaction with proton donors: – RMgX and RLi are strong bases δ- δ+ δ+ δ- + 2+ - - pK = -35 CH3 CH 2 -MgBr + H-OH CH3 CH 2 -H Mg ++OH Br eq Stronger pKa 15.7 pKa 51 Weaker base Stronger Weaker base acid acid – they react readily with these proton acids R2 NHRC CH ROH HOH ArOH RSH RCOOH pKa 38-40 pKa 25 pKa 16-18 pKa 15.7 pKa 9-10 pKa 8-9 pKa 4-5 1° and 2° Terminal Alcohols Water Phenols Thiols Carboxylic Amines alkynes acids This is often an undesired side reaction-to be avoided!! 9 Organic Lecture Series Organometallic reagents have 2 general types of reactions: 1. As Strong bases (Bronsted-Lowry) 2. As nucleophilic reagents: CH3 CH2 CH2 MgBr Regard the alkyl group as “R-” 10 Organic Lecture Series Organometallic reagents • RMgX and RLi are valuable in synthesis as nucleophiles – the carbon bearing the halogen is transformed from an electrophile to a nucleophile carbon is an carbon is a electrophile nucleophile H H H δ+ δ- H CBr C - Mg 2+ Br - CH3 CH2 CH2 CH3 CH2 CH2 – their most valuable use is addition to the electrophilic carbon of C=O groups of aldehydes, ketones, carboxylic esters, and acid chlorides to form a new carbon-carbon bonds 11 Organic Lecture Series General Reactions of Grignard Reagents O OH 1) R" Mg X C C + R R(H) 2) H3O R R(H) R" 12 Organic Lecture Series • Reaction with oxiranes (epoxides) – reaction of RMgX or RLi with an oxirane followed by protonation gives a primary alcohol with a carbon chain two carbons longer than the original chain MgBr + O Butylmagnesium Ethylene bromide oxide O MgBr + OH A magnesium 1-Hexanol alkoxide 13 Organic Lecture Series • Reaction with oxiranes (epoxides) – the major product corresponds to SN2 attack of RMgX or RLi on less hindered carbon of the epoxide MgBr + O Phenyl- Methyloxirane magnesium (Propylene oxide) bromide (racemic) HCl - + O MgBr H2 O OH A magnesium 1-Phenyl-2-propanol alkoxide (racemic) 14 A Simple Example: Organic Lecture Series MgBr O O H OH H 3 C CH3 H 3 C CH3 CH3 CH2 CH2 CH3 CH2 CH2 MgBr alkoxide O H H C CH H 2 O 3 3 MgBrOH Mg(OH)2 CH3 CH2 CH2 alcohol 15 Organic Lecture Series Gilman reagents • Lithium diorganocopper reagents, known more commonly as Gilman reagents – prepared by treating an alkyl, aryl, or alkenyl lithium compound with Cu(I) iodide diethyl ether 2CH CH CH CH Li + CuI 3 2 2 2 or THF Butyllithium Copper(I) iodide - + (CH3 CH2 CH2 CH2 ) 2 Cu Li + LiI Lithium dibutylcopper (a Gilman reagent) 16 Organic Lecture Series Coupling within organohalogen compounds – form new carbon-carbon bonds by coupling with alkyl chlorides, bromides, and iodides diethylether R'Br + R CuLi R'-R ++RCu LiBr 2 or THF 17 Organic Lecture Series Coupling within organohalogen compounds – form new carbon-carbon bonds by coupling with alkenyl chlorides, bromides, and iodides 2 1. Li, pentane I CuLi 2. CuI 2 1-Iododecane diethyl ether Br or THF 2-Methyl-1-dodecene 18 Organic Lecture Series coupling with a vinylic halide is stereospecific: the configuration of the carbon-carbon double bond is retained diethyl ether I + CuLi 2 or THF trans-1-Iodo-1-nonene Li thi u m dibutylcopper trans-5-Tridecene R R + R2CuLi etherorTHF X R 19 Organic Lecture Series • A variation on the preparation of a Gilman reagent is to use a Grignard reagent with a catalytic amount of a copper(I) salt CH (CH ) 3 2 7 (CH2 ) 7 CH 2 Br Cu+ CC + CH (CH ) Mg Br 3 2 4 THF H H (Z)-1-Bromo-9-octadecene CH3 (CH2) 7 (CH2 ) 12CH3 CC HH (Z)-9-Tricosene (Muscalure) 20 Organic Lecture Series Carbenes & Carbenoids • Carbene, R2C: a neutral molecule in which a carbon atom is surrounded by only six valence electrons • Methylene, the simplest carbene – prepared by photolysis or thermolysis of diazomethane : + h : ν H2 CNN H2C: + :NN: Methylene (the simplest carbene) – methylene prepared in this manner is so nonselective that it is of little synthetic use 21 Organic Lecture Series Carbenes & Carbenoids Dichlorocarbene – prepared by treating chloroform with potassium tert-butoxide - + + - CH Cl3 + (CH3 )3 CO K Cl 2 C:+ ( CH3 ) 3 COH+ K Cl Trichloromethane Potassium Dichloro- tert-Butyl (Cloroform) tert-butoxide carbene alcohol 22 Organic Lecture Series Dichlorocarbene reacts with alkenes to give dichlorocyclopropanes H Cl2C: + CCl2 H Dichloro- A dichloro- carbene cyclopropane - + (CH3 ) 3CO K Cl + HCCl3 H H cis- 3-Hexene Cl cis- 1,1-Dichloro- 2,3-diethylcyclopropane 23 Organic Lecture Series • Simmons-Smith reaction – a way to add methylene to an alkene to form a cyclopropane – generation of the Simmons-Smith reagent CH I + Zn( Cu) ICH ZnI 2 2 diethyl ether 2 Diiodo- Zinc-copper Iodomethylzinc iodide methane couple (Simmons-Smith reagent) – this organozinc compound reacts with a wide variety of alkenes to give cyclopropanes (prepared by: Zn dust; CuCl & heat) 24 Organic Lecture Series Simmons-Smith reaction: the organozinc compound reacts with an alkene by a concerted mechanism* I CH2 ZnI2 + H2C I Zn *concerted mechanism-one in which there is simultaneous bond breaking and bond formation. 25 Organic Lecture Series Uses of the Simmons-Smith reagent: Zn(Cu) + CH2I2 + ZnI2 diethyl ether Methylene- Spiro[4.2]heptane cyclopentan e O O H Zn(Cu) + CH2I2 CH + ZnI2 diethyl ether 2 H 2-Cyclohexenone Bicyclo[4.1.0]heptan-2-one 26 Organic Lecture Series Example of a drug which has a cyclopropane moiety: Naltrexone 3 •Sedation •Analgesia •Euphoria •Constipation (GI) opioid receptor antagonist used primarily in •Respiratory depression the management of alcohol dependence •Addiction liability and opioid dependence. 27.
Load more

Recommended publications
  • Chapter 21 the Chemistry of Carboxylic Acid Derivatives
    Instructor Supplemental Solutions to Problems © 2010 Roberts and Company Publishers Chapter 21 The Chemistry of Carboxylic Acid Derivatives Solutions to In-Text Problems 21.1 (b) (d) (e) (h) 21.2 (a) butanenitrile (common: butyronitrile) (c) isopentyl 3-methylbutanoate (common: isoamyl isovalerate) The isoamyl group is the same as an isopentyl or 3-methylbutyl group: (d) N,N-dimethylbenzamide 21.3 The E and Z conformations of N-acetylproline: 21.5 As shown by the data above the problem, a carboxylic acid has a higher boiling point than an ester because it can both donate and accept hydrogen bonds within its liquid state; hydrogen bonding does not occur in the ester. Consequently, pentanoic acid (valeric acid) has a higher boiling point than methyl butanoate. Here are the actual data: INSTRUCTOR SUPPLEMENTAL SOLUTIONS TO PROBLEMS • CHAPTER 21 2 21.7 (a) The carbonyl absorption of the ester occurs at higher frequency, and only the carboxylic acid has the characteristic strong, broad O—H stretching absorption in 2400–3600 cm–1 region. (d) In N-methylpropanamide, the N-methyl group is a doublet at about d 3. N-Ethylacetamide has no doublet resonances. In N-methylpropanamide, the a-protons are a quartet near d 2.5. In N-ethylacetamide, the a- protons are a singlet at d 2. The NMR spectrum of N-methylpropanamide has no singlets. 21.9 (a) The first ester is more basic because its conjugate acid is stabilized not only by resonance interaction with the ester oxygen, but also by resonance interaction with the double bond; that is, the conjugate acid of the first ester has one more important resonance structure than the conjugate acid of the second.
    [Show full text]
  • EI-ICHI NEGISHI Herbert C
    MAGICAL POWER OF TRANSITION METALS: PAST, PRESENT, AND FUTURE Nobel Lecture, December 8, 2010 by EI-ICHI NEGISHI Herbert C. Brown Laboratories of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907-2084, U.S.A. Not long ago, the primary goal of the synthesis of complex natural products and related compounds of biological and medicinal interest was to be able to synthesize them, preferably before anyone else. While this still remains a very important goal, a number of today’s top-notch synthetic chemists must feel and even think that, given ample resources and time, they are capable of synthesizing virtually all natural products and many analogues thereof. Accepting this notion, what would then be the major goals of organic synthesis in the twenty-first century? One thing appears to be unmistakably certain. Namely, we will always need, perhaps increasingly so with time, the uniquely creative field of synthetic organic and organometallic chemistry to prepare both new and existing organic compounds for the benefit and well-being of mankind. It then seems reasonably clear that, in addition to the question of what compounds to synthesize, that of how best to synthesize them will become increasingly important. As some may have said, the primary goal would then shift from aiming to be the first to synthesize a given compound to seeking its ultimately satisfactory or “last synthesis”. If one carefully goes over various aspects of organic synthetic methodology, one would soon note how primitive and limited it had been until rather recently, or perhaps even today. For the sake of argument, we may propose here that the ultimate goal of organic synthesis is “to be able to synthesize any desired and fundamentally synthesizable organic compounds (a) in high yields, (b) efficiently (in as few steps as possible, for example), (c) selectively, preferably all in t98–99% selectivity, (d) economically, and (e) safely, abbreviated hereafter as the y(es)2 manner.” with or without catalyst R1M + R2X R1R2 + MX R1, R2: carbon groups.
    [Show full text]
  • FAROOK COLLEGE (Autonomous)
    FAROOK COLLEGE (Autonomous) M.Sc. DEGREE PROGRAMME IN CHEMISTRY CHOICE BASED CREDIT AND SEMESTER SYSTEM-PG (FCCBCSSPG-2019) SCHEME AND SYLLABI 2019 ADMISSION ONWARDS 1 CERTIFICATE I hereby certify that the documents attached are the bona fide copies of the syllabus of M.Sc. Chemistry Programme to be effective from the academic year 2019-20 onwards. Date: Place: P R I N C I P A L 2 FAROOK COLLEGE (AUTONOMOUS) MSc. CHEMISTRY (CSS PATTERN) Regulations and Syllabus with effect from 2019 admission Pattern of the Programme a. The name of the programme shall be M.Sc. Chemistry under CSS pattern. b. The programme shall be offered in four semesters within a period of two academic years. c. Eligibility for admission will be as per the rules laid down by the College from time to time. d. Details of the courses offered for the programme are given in Table 1. The programme shall be conducted in accordance with the programme pattern, scheme of examination and syllabus prescribed. Of the 25 hours per week, 13 hours shall be allotted for theory and 12 hours for practical; 1 theory hour per week during even semesters shall be allotted for seminar. Theory Courses In the first three semesters, there will be four theory courses; and in the fourth semester, three theory courses. All the theory courses in the first and second semesters are core courses. In the third semester there will be three core theory courses and one elective theory course. College can choose any one of the elective courses given in Table 1.
    [Show full text]
  • Cross-Coupling Reaction of Allylic Ethers with Aryl Grignard Reagents Catalyzed by a Nickel Pincer Complex
    molecules Article Cross-Coupling Reaction of Allylic Ethers with Aryl Grignard Reagents Catalyzed by a Nickel Pincer Complex Toru Hashimoto * , Kei Funatsu, Atsufumi Ohtani, Erika Asano and Yoshitaka Yamaguchi * Department of Advanced Materials Chemistry, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan; [email protected] (K.F.); [email protected] (A.O.); [email protected] (E.A.) * Correspondence: [email protected] (T.H.); [email protected] (Y.Y.); Tel.: +81-45-339-3940 (T.H.); +81-45-339-3932 (Y.Y.) Academic Editor: Kouki Matsubara Received: 30 May 2019; Accepted: 18 June 2019; Published: 21 June 2019 Abstract: A cross-coupling reaction of allylic aryl ethers with arylmagnesium reagents was investigated using β-aminoketonato- and β-diketiminato-based pincer-type nickel(II) complexes as catalysts. An β-aminoketonato nickel(II) complex bearing a diphenylphosphino group as a third donor effectively catalyzed the reaction to afford the target cross-coupled products, allylbenzene derivatives, in high yield. The regioselective reaction of a variety of substituted cinnamyl ethers proceeded to give the corresponding linear products. In contrast, α- and γ-alkyl substituted allylic ethers afforded a mixture of the linear and branched products. These results indicated that the coupling reaction proceeded via a π-allyl nickel intermediate. Keywords: pincer-type nickel(II) complex; cross-coupling; allylic ether 1. Introduction Transition metal-catalyzed cross-coupling reactions are efficient and widely utilized synthetic protocols for constructing carbon–carbon bonds [1]. The reactions of allylic electrophiles with aryl metal reagents provide promising methodologies for the formation of C(sp3)–C(sp2) bonds.
    [Show full text]
  • Organometallic Compounds
    Chapter 11 Organometallic compounds Organometallics Reactions using organometallics Organometallic compounds Ch 11 #2 = comp’s containing a carbon-metal bond δ− δ+ C in organometallic comp’ds are nucleophilic. C in organic comp’d (like ROH, RNH , and RX) 2 δ+ δ are electrophilic. − due to ∆EN Ch 11 #3 in substitution reactions a carbon Nu: R-Li and R-MgX Ch 11 #4 (used to be) the two most common organometallics organolithium comp’ds BuLi = an alkyl lithium organomagnesium comp’ds = Grignard reagents 1912 Nobel Prize R, Ar, vinyl all possible; Br (as X) popular Ether (solvent) coordinates Mg, stabilizing it. Reactions of R-Li and R-MgX Ch 11 #5 reacts like a carbanion C:– ~ a C Nu: reactions as C Nu: (like SN(2)) nucleophilic addition to carbonyls ~ more often Chapt 16 Ch 11 #6 R-Li and R-MgX are very strong B: how strong? pKa? − − react even with very weak acid stronger than OH? NH2? useful for preparing deuterated HC Storage and reaction must be acid- and moisture-free. Transmetal(l)ation Ch 11 #7 R-Li is more reactive than R-MgX is. C–Li more polar than C–Mg C of R-Li more nu-philic [better Nu:] transmetalation [metal exchange] to less reactive [more stable] organometallic Coupling using Gilman reagent Ch 11 #8 coupling reaction (in organic chemistry) two hydrocarbon fragments are coupled (to form C–C) with the aid of a (transition) metal catalyst Gilman reagent coupling of R of R-X and R’ of Gilman reagent RX + R’2CuLi R–R’ mechanism? substitution of X with R’? not clear Ch 11 #9 R can be alkyl, aryl, or alkenyl [vinyl] which is not possible by R-Li or R-MgX Is R of Gilman why? they are SN(2).
    [Show full text]
  • Of Grignard Reagent Formation. the Surface Nature of the Reaction
    286 Ace. Chem. Res. 1990,23, 286-293 Mechanism of Grignard Reagent Formation. The Surface Nature of the Reaction H. M. WALBORSKY Dittmer Laboratory of Chemistry, Florida State University, Tallahassee, Florida 32306 Received February 23, 1990 (Revised Manuscript Received May 7, 1990) The reaction of organic halides (Br, C1, I) with mag- Scheme I nesium metal to yield what is referred to today as a Kharasch-Reinmuth Mechanism for Grignard Reagent Grignard reagent has been known since the turn of the Formation century,' The name derives from its discoverer, Nobel (1)(Mg0)AMg*)2y + RX 4 [(M~'~(MQ')~~-,('MQX)+ R.] + laureate Victor Grignard. How this reagent is formed, (Mgo)x-2(MQ')2~MgX)(MgR) that is, how a magnesium atom is inserted into a car- bon-halogen bond, is the subject of this Account. ('4 (Ms0),-*(M9')2~MgX)(MgR) + + (Mg0)x-dMg*)2y+2 + 2RMgX RX + Mg - RMgX Kharasch and Reinmuth,, persuaded by the work of late under the same conditions gave Itl = 6.2 X s-l. Another system that meets the above criterion is the Gomberg and Bachmad as well as by product analyses of many Grignard formation reactions that existed in vinyl system. The lack of reactivity of vinyl halides toward SN1reactions is well-known and is exemplified the literature prior to 1954,speculated that the reaction involved radicals and that the radical reactions might by the low solvolysis rate of 2-propenyl triflate5 in 80% involve "surface adherent radicals, at least in part". The ethanol at 25 OC, kl being 9.8 X s-l.
    [Show full text]
  • The Ozonolysis of Phenyl Grignard Reagent
    University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1971 The ozonolysis of phenyl Grignard reagent Gale Manning Sherrodd The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Sherrodd, Gale Manning, "The ozonolysis of phenyl Grignard reagent" (1971). Graduate Student Theses, Dissertations, & Professional Papers. 8297. https://scholarworks.umt.edu/etd/8297 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. THE OZONOLYSIS OF PHENYL GRIGNARD REAGENT By Gale M. Sherrodd B.S., Rocky Mountain College, I969 Presented in partial fulfillment of the requirements for the degree of Master of Arts for Teachers UNIVERSITY OF MONTANA 1971 Approved by: Chairman, Board of Examiners De^ , Graduate *School / n ? / Date Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: EP39098 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMT DiMMtstion PuWiahing UMI EP39098 Published by ProQuest LLC (2013). Copyright in the Dissertation held by the Author.
    [Show full text]
  • Recent Progress in the Use of Pd-Catalyzed C-C Cross-Coupling Reactions in the Synthesis of Pharmaceutical Compounds
    http://dx.doi.org/10.5935/0103-5053.20140255 J. Braz. Chem. Soc., Vol. 25, No. 12, 2186-2214, 2014. Printed in Brazil - ©2014 Sociedade Brasileira de Química 0103 - 5053 $6.00+0.00 Review Recent Progress in the Use of Pd-Catalyzed C-C Cross-Coupling Reactions in the Synthesis of Pharmaceutical Compounds André F. P. Biajoli, Cristiane S. Schwalm, Jones Limberger, Thiago S. Claudino and Adriano L. Monteiro* Laboratory of Molecular Catalysis, Institute of Chemistry, UFRGS, Av. Bento Gonçalves, 9500, 91501-970 Porto Alegre-RS, Brazil A grande capacidade do paládio de formar ligações carbono-carbono entre substratos apropriadamente funcionalizados permitiu que os químicos orgânicos efetuassem transformações antes impossíveis ou alcançáveis somente através de rotas muito longas. Neste contexto, uma das mais elegantes e importantes aplicações das reações de acoplamento cruzado catalisadas por paládio é a síntese de compostos de interesse farmacêutico. A presente revisão tem por objetivo apresentar uma visão geral do uso de acoplamentos cruzados na síntese de componentes de medicamentos (ou de candidatos a medicamentos), independentemente da escala, compreendendo o período de 2011 até o final de julho de 2014. The impressive ability of palladium to assemble C-C bonds between appropriately functionalized substrates has allowed synthetic organic chemists to perform transformations that were previously impossible or only possible using multi-step approaches. In this context, one of the most important and elegant applications of the Pd-catalyzed C-C coupling reactions currently is the synthesis of pharmaceuticals. This review is intended to give a picture of the applications of Pd-catalyzed C-C cross-coupling reactions for the synthesis of drug components or drug candidates regardless of the scale from 2011 through to the end of July, 2014.
    [Show full text]
  • Structures and Reaction Mechanisms of Organocuprate Clusters in Organic Chemistry
    REVIEWS Wherefore Art Thou Copper? Structures and Reaction Mechanisms of Organocuprate Clusters in Organic Chemistry Eiichi Nakamura* and Seiji Mori Organocopper reagents provide the principles. This review will summarize example of molecular recognition and most general synthetic tools in organic first the general structural features of supramolecular chemistry, which chemistry for nucleophilic delivery of organocopper compounds and the pre- chemists have long exploited without hard carbanions to electrophilic car- vious mechanistic arguments, and then knowing it. Reasoning about the bon centers. A number of structural describe the most recent mechanistic uniqueness of the copper atom among and mechanistic studies have been pictures obtained through high-level neighboring metal elements in the reported and have led to a wide variety quantum mechanical calculations for periodic table will be presented. of mechanistic proposals, some of three typical organocuprate reactions, which might even be contradictory to carbocupration, conjugate addition, Keywords: catalysis ´ conjugate addi- others. With the recent advent of and SN2 alkylation. The unified view tions ´ copper ´ density functional physical and theoretical methodolo- on the nucleophilic reactivities of met- calculations ´ supramolecular chemis- gies, the accumulated knowledge on al organocuprate clusters thus ob- try organocopper chemistry is being put tained has indicated that organocup- together into a few major mechanistic rate chemistry represents an intricate 1. Introduction 1 R Cu X The desire to learn about the nature of elements has been R or R1 R and will remain a main concern of chemists. In this review, we R Cu will consider what properties of copper make organocopper R1 chemistry so useful in organic chemistry.
    [Show full text]
  • The 2010 Chemistry Nobel Prize: Pd(0)-Catalyzed Organic Synthesis
    GENERAL ARTICLE The 2010 Chemistry Nobel Prize: Pd(0)-Catalyzed Organic Synthesis Gopalpur Nagendrappa and Y C Sunil Kumar The 2010 Nobel Prize in Chemistry was awarded to three scientists, R F Heck, E-I Negishi and A Suzuki, for their work on “Palladium – Catalyzed Cross Couplings in Organic Syn- (left) G Nagendrappa thesis”. It pertains to research done over a period of four was a Professor of decades. The synthetic procedures embodied in their work Organic Chemistry at enable construction of C–C bond selectively between complex Bangalore University, molecules as in simple ones at desired positions without and Head of the Department of Medici- disturbing any functional groups at other parts of the reacting nal Chemistry, Sri molecules. The work finds wide applications in the synthesis Ramachandra (Medical) of pharmaceuticals, agricultural chemicals, and molecules for University, Chennai. electronics and other applications. It would not have been He is currently in Jain University, Bangalore. possible to synthesize some of the complex natural products or He continues to teach synthetic compounds without using these coupling reactions and do research. His in one or more steps. work is in the area of organosilicon chemis- Introduction try, synthetic and mechanistic organic In mythical stories and folk tales we come across characters that, chemistry, and clay- catalysed organic while uttering some manthras (words of charm), throw a pinch or reactions (Green fistful of a magic powder, and suddenly there appears the object Chemistry). or person they wished for or an event happens the way they want. (right) Sunil Kumar is A large number of movies have been made with such themes and a PhD from Mysore characters that would be depicted as ‘scientists’.
    [Show full text]
  • Grignard Reaction: Synthesis of Triphenylmethanol
    *NOTE: Grignard reactions are very moisture sensitive, so all the glassware in the reaction (excluding the work-up) should be dried in an oven with a temperature of > 100oC overnight. The following items require oven drying. They should be placed in a 150mL beaker, all labeled with a permanent marker. 1. 5mL conical vial (AKA: Distillation receiver). 2. Magnetic spin vane. 3. Claisen head. 4. Three Pasteur pipettes. 5. Two 1-dram vials (Caps EXCLUDED). 6. One 2-dram vial (Caps EXCLUDED). 7. Glass stirring rod 8. Adaptor (19/22.14/20) Grignard Reaction: Synthesis of Triphenylmethanol Pre-Lab: In the “equations” section, besides the main equations, also: 1) draw the equation for the production of the byproduct, Biphenyl. 2) what other byproduct might occur in the reaction? Why? In the “observation” section, draw data tables in the corresponding places, each with 2 columns -- one for “prediction” (by answering the following questions) and one for actual drops or observation. 1) How many drops of bromobenzene should you add? 2) How many drops of ether will you add to flask 2? 3) 100 µL is approximately how many drops? 4) What are the four signs of a chemical reaction? (Think back to Chem. 110) 5) How do the signs of a chemical reaction apply to this lab? The Grignard reaction is a useful synthetic procedure for forming new carbon- carbon bonds. This organometallic chemical reaction involves alkyl- or aryl-magnesium halides, known as Grignard 1 reagents. Grignard reagents are formed via the action of an alkyl or aryl halide on magnesium metal.
    [Show full text]
  • Grignard Reagents and Silanes
    GRIGNARD REAGENTS AND SILANES By B. Arkles REPRINTED FROM HANDBOOK OF GRIGNARD REAGENTS by G. Silverman and P. Rakita Pages 667-675 Marcel Dekker, 1996 Gelest, Inc. 612 William Leigh Drive Tullytown, Pa. 19007-6308 Phone: [215] 547-1015 Fax: [215] 547-2484 Grignard Reagents and Silanes 32 Grignard Reagents and Silanes BARRY ARKLES Gelest Inc., Tullytown, Pennsylvania I. INTRODUCTION This review considers two aspects of the interaction of Grignards with silanes. First, focusing on technologies that are still viable within the context of current organosilane and silicone technology, guidelines are provided for silicon-carbon bond formation using Grignard chemistry. Second, the use of silane-blocking agents and their stability in the presence of Grignard reagents employed in organic synthesis is discussed. II. FORMATION OF THE SILICON-CARBON BOND A. Background The genesis of current silane and silicone technology traces back to the Grignard reaction. The first practical synthesis of organosilanes was accomplished by F. Stanley Kipping in 1904 by the Grignard reaction for the formation of the silicon-carbon bond [1]. In an effort totaling 57 papers, he created the basis of modern organosilane chemistry. The development of silicones by Frank Hyde at Corning was based on the hydrolysis of Grignard-derived organosilanes [2]. Dow Corning, the largest manufacturer of silanes and silicones, was formed as a joint venture between Corning Glass, which had silicone product technology, and Dow, which had magnesium and Grignard technology, during World War II. In excess of 10,000 silicon compounds have been synthesized by Grignard reactions. Ironically, despite the versatility of Grignard chemistry for the formation of silicon-carbon bonds, its use in current silane and silicone technology has been supplanted by more efficient and selective processes for the formation of the silicon-carbon bond, notably by the direct process and hydrosilylation reactions.
    [Show full text]