DOCSLIB.ORG

Experiment 4: Preparation of Benzoic Acid

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Experiment 4: Preparation of Benzoic Acid Experiment 4: Preparation of Benzoic Acid INTRODUCTION This experiment is designed both as a preparative and an investigative project. Two outcomes are expected: preparation of benzoic acid from bromobenzene and analysis of the by-products of a Grignard reaction, an integral part of the synthetic procedure. GC/MS analysis of the organic layer, generated in the reaction of a Grignard reagent with CO2, will provide experimental evidence for the nature of the by-products. The mechanism of the Grignard reaction has been provided in this hand-out, and students will provide the structure of the by-products in the Pre-Lab assignment. Additionally, students will propose refinements of the experimental procedure designed to minimize the amount of by-products. The knowledge of the side products will help students understand how side reactions affect the yield of the desired material. For example, if you are an R&D scientist in a company, you would want to minimize the amount of by- products. The latter reduce the yield of desired compound, therefore increasing the cost of the product. By-products may contaminate the final material, thus further increasing cost due to need for additional purification steps. PART 1: SYNTHETIC PROCEDURE The experiment begins with the preparation of a Grignard reagent, phenylmagnesium bromide (1), from bromobenzene and magnesium metal using diethyl ether (“ether”) as the solvent under anhydrous conditions [equation (1)]. The use of an ether, such as diethyl ether, as a solvent for the preparation of Grignard reagents is of key importance because the lone pairs of electrons on oxygen help stabilize the partial positive charge on magnesium in the Grignard reagent and thus facilitate its formation. Grignard reagents do not form in most other “inert” solvents. In general, ethers like diethyl ether or tetrahydrofuran (THF) work well as solvents in many nucleophilic addition reactions because the ether functional group is unreactive with most reactants. Br MgBr anhydrous ether + Mg (1) bromobenzene phenyl magnesium bromide, 1 Phenyl magnesium bromide will then be allowed to react with CO2, followed by hydrolysis, to give benzoic acid [equation (2)]. 1 O O MgBr H O MgBr (2) + CO2 OH benzoic acid The carbon-containing portion of Grignard reagent, 1, has two characteristics: (1) as a carbanion that serves as a nucleophile for its reaction with carbon dioxide, and (2) as a strong base that reacts with acidic hydrogen atoms. These characteristics are illustrated by the structure of the reagent that bears a strongly polar covalent bond between carbon and magnesium. ! ! Ar MgBr represented as ArMgBr (where "Ar" is short for aromatic ring) A. Grignard Reagents as Nucleophiles: Benzoic Acid Of major synthetic interest is the use of Grignard reagents as nucleophiles to form new carbon-carbon bonds, a process that is termed nucleophilic addition. For example, Grignard reagents add to aldehydes to produce secondary alcohols, to ketones to produce tertiary alcohols, to carbon dioxide to form carboxylic acids, and to epoxides to form alcohols. Two moles of the reagent add to esters and acid chlorides to form tertiary alcohols. As a nucleophile, the Grignard attacks the carbon atom in a carbonyl group because that carbon atom has electrophilic character owing to the polarity of the C=O group. The carbon atom bears some partially positive charge because it is attached to the more electronegative oxygen atom. ! ! C O The synthetic use of the Grignard reagent, phenylmagnesium bromide, in this experiment is its addition to carbon dioxide to produce, after hydrolysis, benzoic acid [equation (2)]. The mechanism for this reaction is provided in equation (3). A convenient source of CO2 is Dry-Ice (solid CO2) which will be used in this experiment. 2 O O MgBr O + O MgBr H C OH + Mg2+ + Br (3) O benzoic acid B. Grignard Reagents as Strong Bases Any compound with an acidic hydrogen — such as H2O, an alcohol (ROH), a carboxylic acid (RCOOH), or any acid — will donate a proton to a Grignard reagent such as phenyl magnesium bromide and destroy it by forming a new C–H bond. To avoid this undesired side reaction, Grignard reagents are prepared under anhydrous conditions. All apparatus and all reagents (magnesium metal, bromobenzene, and the ether solvent) must be free from traces of moisture. Thus, the apparatus is dried by heating, and anhydrous reagents can usually be purchased commercially. Once dried and assembled, the apparatus used for preparing the Grignard reagent is protected from moisture by attaching a drying tube containing anhydrous calcium chloride, which absorbs moisture from air entering the system. Even so, the procedures used in this synthesis minimize the presence of moisture but do not completely exclude it. C. Isolation and Purification of Benzoic Acid After phenyl magnesium bromide is prepared, it is poured over powdered Dry-Ice (solid CO2) to obtain the bromomagnesium salt of benzoic acid. Additional ether is added and the resulting mixture is made distinctly acidic by the addition of aqueous hydrochloric acid. The HCl protonates the benzoate ion present as the bromomagnesium salt and also dissolves any basic magnesium salts and any unreacted magnesium metal 2+ - + - that may be present. Inorganic ions, such as Mg , Br , H3O , and Cl , remain in the aqueous layer. The ether layer is removed from the aqueous layer, and the ether is then extracted with several portions of aqueous NaOH solution. This converts the benzoic acid into its water-soluble sodium salt, which is now contained in the basic aqueous layer. Several NaOH extractions are done to help ensure complete removal of benzoic acid from the ether layer, and the other organic by-products. Note that you must retain the organic (ether) layer for the optional Part II of this experiment. The combined aqueous sodium hydroxide layers are then boiled gently to remove traces of ether, which is slightly soluble in water. If the basic solution is not boiled before acidification, traces of ether will be present in the aqueous layer and thus dissolve some of the benzoic acid. If the benzoic acid stays dissolved, it will not fully crystallize upon acidification that would then decrease the amount of benzoic acid 3 recovered. Decolorizing charcoal is added before boiling to remove any colored impurities that may be present. The basic solution is then cooled and made distinctly acidic with HCl to precipitate benzoic acid. Upon protonation of the anion, the ionic sodium salt becomes an uncharged organic compound, insoluble in a polar solvent like water. After cooling this mixture in an ice bath, the benzoic acid is collected by vacuum filtration and allowed to air dry. If your instructor desires, it may be recrystallized from hot water. [Note: The ether layer may be analyzed by gas chromatography and mass spectral analysis for the presence of by-products. See Part II for this discussion.] REAGENT/PRODUCT TABLE: Reagents MW (g/mol) MP (ºC) BP (ºC) Density bromobenzene 157.02 -31 156 1.491 Mg 24.3 Dry Ice (CO2) Used in Excess - not the limiting reagent diethyl ether 74.12 -166 34.6 Product MW (g/mol) MP (ºC) BP (ºC) benzoic acid 122.12 122-123 249 EXPERIMENTAL PROCEDURE: Preparation of Phenyl Magnesium Bromide 1. Obtain the following items that have been pre-dried in an oven for you: 1 small sample vial and cap, 1 large sample vial and cap, one 5" Pasteur pipette, one Claisen adapter, and one 5 mL conical vial without cap containing a spin vane. 2. Weigh approximately 75 mg of magnesium turnings. Record amount used in notebook. Use tweezers to handle magnesium turnings. Transfer the Mg turnings to the 5-mL conical vial containing the spin vane. 3. Obtain a drying tube packed with indicating silica gel desiccant pellets, and set up the apparatus as described in Section A.5 and shown in Figure A.5A. Place the vial in the aluminum block on the stirring hot plate. 4. Take the large, dry sample vial to your instructor who will fill it about two-thirds full of anhydrous ether. Tightly cap it, and label it as “ether vial”. 5. (a) For use in Step 6, clean the syringe in the Microscale Kit by drawing several portions of acetone into it (with needle attached). Carefully remove the plunger and place the barrel end of the syringe over the heavy-walled tubing 4 attached to the house vacuum, and pull air through the syringe for a minute to remove the acetone. Carefully reinsert the plunger. (b) Place 0.34 mL of bromobenzene (density = 1.491 g/mL) in a small, dry preweighed sample vial, and then reweigh to determine the weight of bromobenzene you have added. Add 2 mL of anhydrous ether to this vial from the “ether vial”, cap it, and shake it gently to dissolve the bromobenzene in the ether. Label this small vial as “bromobenzene–ether.” 6. Using the clean, dry syringe (Step 5a), transfer all the bromobenzene–ether mixture to the conical vial containing the Mg turnings. This may be done by drawing the bromobenzene–ether mixture into the syringe, inserting the needle through the rubber septum on the reaction apparatus, and injecting the mixture. It will be necessary to refill the syringe several times to get all the bromobenzene–ether mixture into the conical vial, and this should be done as quickly as possible. 7. Turn on the magnetic stirrer (no heat), and stir the mixture gently. The reaction has started when the solution turn light yellow (or darker) color; another indication that the reaction has started is the formation of a brownish-gray, cloudy solution and sometimes even a trace of white precipitate (magnesium hydroxide). If none of these changes are observed after 5–10 min, consult your instructor.
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]
  • Bromobenzene D5
    Safety data sheet according to Regulation (EC) No. 1907/2006 (REACH), amended by 2015/830/EU Bromobenzene D5 99,5 Atom%D article number: HN93 date of compilation: 2020-09-02 Version: 1.0 en SECTION 1: Identification of the substance/mixture and of the company/ undertaking 1.1 Product identifier Identification of the substance Bromobenzene D5 99,5 Atom%D Article number HN93 Registration number (REACH) It is not required to list the identified uses be- cause the substance is not subject to registration according to REACH (< 1 t/a) EC number 224-013-8 CAS number 4165-57-5 1.2 Relevant identified uses of the substance or mixture and uses advised against Identified uses: laboratory chemical laboratory and analytical use 1.3 Details of the supplier of the safety data sheet Carl Roth GmbH + Co KG Schoemperlenstr. 3-5 D-76185 Karlsruhe Germany Telephone: +49 (0) 721 - 56 06 0 Telefax: +49 (0) 721 - 56 06 149 e-mail: [email protected] Website: www.carlroth.de Competent person responsible for the safety data : Department Health, Safety and Environment sheet: e-mail (competent person): [email protected] 1.4 Emergency telephone number Name Street Postal code/ Telephone Website city National Poisons Inform- Dudley Rd B187QH Birm- 844 892 0111 ation Service ingham City Hospital Emergency information service +49/(0)89 19240 SECTION 2: Hazards identification 2.1 Classification of the substance or mixture Classification according to Regulation (EC) No 1272/2008 (CLP) Classification acc. to GHS Section Hazard class Hazard class and cat- Hazard egory state- ment 2.6 flammable liquid (Flam.
    [Show full text]
  • Chem 353: Grignard
    GRIG.1 ORGANIC SYNTHESIS: BENZOIC ACID VIA A GRIGNARD REACTION TECHNIQUES REQUIRED : Reflux with addition apparatus, rotary evaporation OTHER DOCUMENTS Experimental procedure, product spectra INTRODUCTION In this experiment you will synthesise benzoic acid using bromobenzene to prepare a Grignard reagent, which is then reacted with carbon dioxide, worked-up and purified to give the acid. This sequence serves to illustrate some important concepts of practical synthetic organic chemistry : preparing and working with air and moisture sensitive reagents, the "work-up", extractions, apparatus set-up, etc. The synthesis utilises one of the most important type of reagents discussed in introductory organic chemistry, organometallic reagents. In this reaction, the Grignard reagent (an organomagnesium compound), phenylmagnesium bromide is prepared by reaction of bromobenzene with magnesium metal in diethyl ether (the solvent). The Grignard reagent will then be converted to benzoic acid via the reaction of the Grignard reagent with excess dry ice (solid CO2) followed by a "work-up" using dilute aqueous acid : The aryl (or alkyl) group of the Grignard reagent behaves as if it has the characteristics of a carbanion so it is a source of nucleophilic carbon. It is reasonable to represent the structure of the - + Grignard reagent as a partly ionic compound, R ....MgX. This partially-bonded carbanion is a very strong base and will react with acids (HA) to give an alkane: RH + MgAX RMgX + HA Any compound with suitably acidic hydrogens will readily donate a proton to destroy the reagent. Water, alcohols, terminal acetylenes, phenols and carboxylic acids are just some of the functional groups that are sufficiently acidic to bring about this reaction which is usually an unwanted side reaction that destroys the Grignard reagent.
    [Show full text]
  • Addition of a Grignard Reagent to an Ester: Formation of a Tertiary Alcohol
    Addition of a Grignard Reagent to an Ester: Formation of a Tertiary Alcohol Introduction: Grignard reagents are important and versatile reagents in organic chemistry. In this experiment, you will prepare a Grignard reagent and react it with an ester to prepare a tertiary alcohol. Specifically, in this reaction you will prepare phenyl magnesium bromide from bromobenzene and magnesium metal and then react it with methyl benzoate to prepare triphenylmethanol (Figure 1). In this reaction, two equivalents of phenylmagnesium bromide add to methyl benzoate. Note: Grignard reagents are sensitive to water. ALL glassware must be completely clean and dry. Reagents have been stored over molecular sieves to keep them dry in storage, but you should also keep containers closed as much as possible. Finally, water in the air can also react with the Grignard reagents over time. To successfully prepare triphenylmethanol in this experiment, you will need to be well organized and not take too much time between steps. Figure 1. O 1) Me O OH Br Mg MgBr THF + 2) H3O triphenylmethanol Mechanism: The formation of Grignard reagents from aryl halides is a complex mechanism, which takes place on the surface of the magnesium metal. You do not need to concern yourself with the details of this step of the mechanism. Figure 2. MgBr O Bu MgBr Bu MgBr O + OH O Bu MgBr O H3O Me OEt Bu Me OEt Me Bu Me Bu Me –EtOMgBr Bu Bu The mechanism of the reaction of a Grignard reagent with an ester is shown in Figure 2 (using methyl propionate and butylmagnesium bromide).
    [Show full text]
  • TOXICOLOGICAL REVIEW of BROMOBENZENE (CAS No
    EPA/635/R-07/002F www.epa.gov/iris TOXICOLOGICAL REVIEW OF BROMOBENZENE (CAS No. 108-86-1) In Support of Summary Information on the Integrated Risk Information System (IRIS) September 2009 U.S. Environmental Protection Agency Washington, DC DISCLAIMER This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. ii CONTENTS−TOXICOLOGICAL REVIEW OF BROMOBENZENE (CAS No. 108-86-1) LIST OF TABLES......................................................................................................................... vi LIST OF FIGURES ....................................................................................................................... ix LIST OF ABBREVIATIONS AND ACRONYMS ....................................................................... x FOREWORD ................................................................................................................................. xi AUTHORS, CONTRIBUTORS, AND REVIEWERS ................................................................ xii 1. INTRODUCTION ..................................................................................................................... 1 2. CHEMICAL AND PHYSICAL INFORMATION RELEVANT TO ASSESSMENTS .......... 3 3. TOXICOKINETICS .................................................................................................................. 6 3.1. ABSORPTION ................................................................................................................
    [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]
  • Copper(I) Complexes of P‐Stereogenic Josiphos and Related Ligands
    Full Papers doi.org/10.1002/ejoc.202100146 Copper(I) Complexes of P-Stereogenic Josiphos and Related Ligands Ross A. Arthurs,[a] Alice C. Dean,[a] David L. Hughes,[a] and Christopher J. Richards*[a] Starting from (R)-Ugi’s amine, diastereoselective lithiation avoiding the isolation of air-sensitive phosphine intermediates. followed by Ar’PCl2 and then Ar’’MgBr led to the generation, as This protection methodology was also applied to the synthesis single diastereoisomers, of (R,Sp,Sphos) [Ar’=Ph, Ar’’=o-Tol] and of Josiphos/CuCl complexes derived from PCl3. In addition, (R,Sp,Rphos) [Ar’=o-Tol, Ar’’= Ph] PPFA ligand derivatives. Amine related bulky cobalt-sandwich complex-based derivatives were substitution of both with HPCy2 gave P-stereogenic Josiphos also obtained. Preliminary investigation revealed isolated CuCl ligands, and then addition of CuCl, the corresponding copper(I) complexes as competent catalyst precursors for enantioselec- complexes. The latter were also generated by using borane P tive conjugate addition reactions. and N protecting groups and in situ Cu(I) complexation, Introduction Although many ligands have been developed for application in asymmetric synthesis, relatively few have found widespread use. Of these so-called ‘privileged’ ligands,[1] one of the most successful class are the ferrocene-based Josiphos ligands A.[2] Numerous derivatives are known, obtained by varying the identity of R’ and R’’, and many are commercially available. This has aided the incorporation of A into many ligand screening exercises, often leading to a successful outcome.[3] In particular, in situ generated Josiphos-copper complexes have been applied Scheme 1.
    [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]
  • CF 7.4 V2.Indd
    2007 VOLUME 7 NUMBER 4 Product Directory Grignard and Organozinc Reagents RIEKE® HIGHLY REACTIVE METALS GRIGNARD REAGENTS ORGANOZINC HALIDES DIALKYLMAGNESIUM AND DIALKYZINC REAGENTS 2-Pyridylzinc bromide: a shelf-stable 2-pyridyl anion equivalent; an important motif in many pharmacologically active molecules. sigma-aldrich.com 2 Table of Contents Sigma-Aldrich is committed to providing the most extensive portfolio of high-quality Grignard, organozinc, and other organometallic reagents, and we continually expand our product listing. Within each section of this directory, products are listed by increasing carbon content. Rieke® Highly Reactive Metals If viewing the electronic version simply select Grignard Reagents a category to jump to that section or activate Alkyl Alkenyl Alkynyl Aryl Heteroaryl your Adobe Bookmarks. You may also search by name, product number, molecular formula, Organozinc Halides or CAS registry number simply by using the “find” feature in Adobe (Ctrl+F in Windows or Alkyl Alkenyl Aryl Heteroaryl Introduction Command+F in a Mac environment). Dialkylmagnesium and Dialkylzinc Reagents If you are unable to find a reagent for your research “Please Bother Us” at [email protected], or contact your local Sigma-Aldrich office (see back cover). Foreword Reuben D. Rieke President and CEO, Rieke Metals, Inc. Professor Emeritus, University of Nebraska Lincoln, NE In the last 35 years, considerable research has been done in the area of generating reactive metals that can be used to synthesize novel organometallic reagents. In 1972, we reported a general approach for preparing highly reactive metal powders, relying on the reduction of metal salts with alkali metals in ethereal or hydrocarbon solvents.
    [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]
  • TOXICOLOGICAL REVIEW of BROMOBENZENE (CAS No
    DRAFT - DO NOT CITE OR QUOTE EPA/635/R-07/002 www.epa.gov/iris TOXICOLOGICAL REVIEW OF BROMOBENZENE (CAS No. 108-86-1) In Support of Summary Information on the Integrated Risk Information System (IRIS) June 2007 NOTICE This document is an interagency review draft. It has not been formally released by the U.S. Environmental Protection Agency and should not at this stage be construed to represent Agency position on this chemical. It is being circulated for review of its technical accuracy and science policy implications. U.S. Environmental Protection Agency Washington, DC DISCLAIMER This document is a preliminary draft for review purposes only and does not constitute U.S. Environmental Protection Agency policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 6/7/07 ii DRAFT – DO NOT CITE OR QUOTE CONTENTSCTOXICOLOGICAL REVIEW OF BROMOBENZENE (CAS No. 108-86-1) LIST OF FIGURES ....................................................................................................................... vi LIST OF TABLES........................................................................................................................ vii LIST OF ABBREVIATIONS AND ACRONYMS ........................................................................x FOREWORD ................................................................................................................................. xi AUTHORS, CONTRIBUTORS, AND REVIEWERS ................................................................ xii
    [Show full text]