DOCSLIB.ORG

H C C 9.5 Acidity of Acetylene and Terminal Alkynes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
H C C 9.5 Acidity of Acetylene and Terminal Alkynes 9.5 Acidity of Acetylene and Terminal Alkynes H C C Acidity of Hydrocarbons In general, hydrocarbons are exceedingly weak acids Compound pKa HF 3.2 H2O 16 NH3 36 45 H2C CH2 CH4 60 Acetylene Acetylene is a weak acid, but not nearly as weak as alkanes or alkenes. Compound pKa HF 3.2 H2O 16 HC CH 26 NH3 36 H2C CH2 45 CH4 60 Carbon: Hybridization and Electronegativity 10-60 C H H+ + C : sp3 H 2 10-45 : sp C C H+ + C C 10-26 C C H H+ + C C : sp Electrons in an orbital with more s character are closer to the nucleus and more strongly held. Sodium Acetylide Objective: Prepare a solution containing sodium acetylide NaC CH Will treatment of acetylene with NaOH be effective? + + NaOH + HC CH NaC CH + H2O Sodium Acetylide No. Hydroxide is not a strong enough base to deprotonate acetylene. + + NaOH HC CH NaC CH H2O .. – .. – : + HO H + :C CH HO.. H C CH .. weaker acid stronger acid pKa = 26 pKa = 16 In acid-base reactions, the equilibrium lies to the side of the weaker acid. Sodium Acetylide Solution: Use a stronger base. Sodium amide is a stronger base than sodium hydroxide. + + NaNH2 HC CH NaC CH NH3 .. – .. – + H2N: + H C CH H2N H :C CH stronger acid weaker acid pKa = 26 pKa = 36 Ammonia is a weaker acid than acetylene. The position of equilibrium lies to the right. 9.6 Preparation of Alkynes by Alkylation of Acetylene and Terminal Alkynes Preparation of Alkynes There are two main methods for the preparation of alkynes: Carbon-carbon bond formation alkylation of acetylene and terminal alkynes Functional-group transformations elimination Alkylation of Acetylene and Terminal Alkynes H—C C—H R—C C—H R—C C—R Alkylation of Acetylene and Terminal Alkynes – – SN2 H—C C: + R X H—C C—R + : X– The alkylating agent is an alkyl halide, and the reaction is nucleophilic substitution. The nucleophile is sodium acetylide or the sodium salt of a terminal (monosubstituted) alkyne. Example: Alkylation of Acetylene NaNH2 HC CH HC CNa NH3 CH3CH2CH2CH2Br HC C CH2CH2CH2CH3 (70-77%) Example: Alkylation of a Terminal Alkyne (CH3)2CHCH2C CH NaNH2, NH3 (CH3)2CHCH2C CNa CH3Br (CH3)2CHCH2C C—CH3 (81%) Example: Dialkylation of Acetylene H—C C—H 1. NaNH2, NH3 2. CH3CH2Br CH3CH2—C C—H 1. NaNH2, NH3 2. CH3Br CH3CH2—C C—CH3 (81%) Limitation Effective only with primary alkyl halides Secondary and tertiary alkyl halides undergo elimination Acetylide Ion as a Base E2 predominates over SN2 when alkyl halide is secondary or tertiary – H—C C: H C C X E2 H—C C—H + C C + : X– 9.7 Preparation of Alkynes by Elimination Reactions Preparation of Alkynes by "Double Dehydrohalogenation" H X H H C C C C H X X X Geminal dihalide Vicinal dihalide The most frequent applications are in preparation of terminal alkynes. Geminal dihalide Æ Alkyne (CH3)3CCH2—CHCl2 1. 3NaNH2, NH3 2. H2O (CH3)3CC CH (56-60%) Geminal dihalide Æ Alkyne (CH3)3CCH2—CHCl2 NaNH2, NH3 (slow) (CH3)3CCH CHCl (slow) NaNH2, NH3 (CH3)3CC CH H O 2 NaNH2, NH3 (fast) (CH3)3CC CNa Vicinal dihalide Æ Alkyne CH3(CH2)7CH—CH2Br Br 1. 3NaNH2, NH3 2. H2O CH3(CH2)7C CH (54%).
Load more

Recommended publications
  • And C,N-Chelated Organocopper Compounds†
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 2 September 2021 Review C,C- and C,N-Chelated Organocopper Compounds† Liang Liu1, Hui Chen2, Zhenqiang Yang2, Junnian Wei1* and Zhenfeng Xi1,3* 1 Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China; [email protected] (L.L.), [email protected] (J.W.), [email protected] (Z.X.) 2 Henan Institute of Chemistry Co. Ltd., Henan Academy of Sciences, Zhengzhou 450002, China; [email protected] (H.C.), [email protected] (Z.Y.) 3 State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry (SIOC), Shanghai 200032, China; [email protected] (Z.X.) * Correspondence: [email protected] (J.W.), [email protected] (Z.X.) † Dedicated to Professor Gerard van Koten on the occasion of his 80th birthday Abstract: Copper-catalyzed and organocopper-involved reactions are of great significance in organic synthesis. To have a deep understanding of the reaction mechanisms, the structural characterizations of organocopper intermediates become indispensable. Meanwhile, the structure- function relationship of organocopper compounds would advance rational design and development of new Cu-based reactions and organocopper reagents. Compared to the mono- carbonic ligand, the C,N- and C,C-bidentate ligands better stabilize the unstable organocopper compounds. The bidentate ligands can chelate to the same copper atom via 휂2-mode, forming a mono-cupra-cyclic compounds with at least one acute C-Cu-C angle. When the bidentate ligands bind to two copper atoms via 휂1-mode at each coordinating site, the bimetallic macrocyclic compounds will form nearly linear C-Cu-C angles.
    [Show full text]
  • Conversion of Carbon Dioxide to Acetylene on a Micro Scale
    810 NATURE June 14, 1947 Vol. 159 orbitale of the ethmoid is reduced". In the orang Stainless steel was found to be the most satis­ and the gibbon a large planum orbitale articulates factory furnace material tried. From mild steel in front with the lacrimal, as in man. The figure relatively large amounts of acetylene were produced we give of the orbital wall in Pleaianthropus shows in blank experiments, and a fused silica envelope a condition almost exactly as in man. fitted with a nickel thimble was found, after it had We are here not at present concerned with the been used with calcium and barium metals, to absorb question of whether man and the Australopithecinre carbon dioxide when hot even when no calcium or have arisen from an early anthropoid, or a pre­ barium was present. In carrying out the absorption anthropoid, or an Old World monkey or a tarsioid ; of carbon dioxide by barium metal in the stainless but we think the evidence afforded by this new skull steel furnace it was found that when the pressure of Plesianthropus shows that the Australopithecinre at which the gas was admitted was less than about and man are very closely allied, and that these small­ 10·1 mm. of mercury, the yield of acetylene was brained man-like beings were very nearly human. variable and only about 45 per cent. Good yields R. BROOM were obtained when the carbon dioxide at its full J. T. RoBINSON pressure was admitted to the furnace before raising Transvaal Museum, Pretoria. the temperature above 400° C.
    [Show full text]
  • Download Download
    — Studies on Lithium Acetylide Kenneth N. Campbell and Barbara K. Campbell, The University of Notre Dame In contrast to the large amount of work done on the acetylene derivatives of sodium, potassium and calcium, little attention has been paid to the analogous compounds of lithium. In 1898 Moissani prepared lithium acetylide on a small scale, by the action of acetylene on a liquid ammonia solution of lithium. He reported that lithium acetylide was less soluble in liquid ammonia than sodium acetylide, and that when isolated from the solvent, it was less stable, undergoing decomposition with evolu- tion of acetylene. On the basis of the weight of lithium acetylide obtained from a given weight of lithium, and from the amount of acetylene liberated on hydrolysis, he assigned to lithium acetylide the formula C2Li2.C2H2.2NH3. Since that time no references to lithium acetylide or lithium alkylacetylides have appeared in the literature. It was the pur- pose of the present work, therefore, to prepare and analyze lithium acetylide and a lithium alkylacetylide, and to compare their reactions with those of the better known sodium derivatives. Experimental Procedure Preparation of Lithium and Sodium Acetylides.—Acetylene gas, washed by bubbling through concentrated sulfuric acid, was passed into two liters of liquid ammonia, while 7 g. (1 mole) of metallic lithium, cut in small pieces, was added gradually, with stirring, at a rate such that the solution did not develop a permanent deep blue color. When the solution became colorless after the addition of the last piece of lithium, the flow of acetylene was stopped.
    [Show full text]
  • United States Patent Office Patented Nov
    3,111,372 United States Patent Office Patented Nov. 19, 1963 1. 2 earth metal borohydrides, which comprises reacting an 3,111,372 PROCESS FOR THE PRODUCTION OF ALKALI N-trialkyl borazane with an alkali metal acetylide or METAL AND ALKALINE EARTH METAL BORO alkaline earth metal acetylide in the presence of hydrogen HYDRIDES under pressure. For example, N-triethyl borazane can Roland Köster, Mulheim (Ruhr), Germany, assignor to 5 be split up at temperatures higher than 140 C., prefer Studiengesellschaft Kohle m.b.H., Mulheim (Ruhr), ably between 200 and 300° C. by calcium carbide, the Germany acetylide fraction of the calcium carbide becoming free No Drawing. Filed Apr. 28, 1958, Ser. No. 731,125 mostly in the form of ethane. The temperatures used are Claims priority, application Germany Apr. 30, 1957 so low that the initial formation of calcium hydride from 7 Claims. (C. 23-14) O calcium carbide must be considered as not occurring in This invention relates to a process for the production of practice, since the temperatures at which calcium carbide alkali metal and alkaline earth metal borohydrides. reacts with hydrogen alone to form calcium hydride are Belgian patent specification No. 559,053 discloses a substantially higher. Moreover, calcium carbide only process for the production of alkali metal and alkaline reacts easily with hydrogen to form calcium hydride if earth metal borohydrides from borazanes having 3 hydro certain catalysts are present, and in addition the calcium carbon radicals, especially N-trialkyl borazanes, by re hydride formation requires a substantially higher tem action with an alkali metal or alkaline earth metal hy perature than is necessary in the process of the inven dride, with a metal compound of the general formulae tion.
    [Show full text]
  • Mixed Metal Acetylides: the Ptii Aryl Acetylide "[Ptc6h2(Ch2nme2)22,6
    FULL PAPER II Mixed Metal Acetylides: The Pt Aryl Acetylide ‘‘[PtC6H2(CH2NMe2)2- 2,6-(C;C)-4]’’ as a Connective Fragment Stephan Back,[a] Robert A. Gossage,[b] Heinrich Lang,*[a] and Gerard van Koten*[b] Keywords: Alkynes / Cyclic voltammetry / Metal-metal interactions / Conjugation / Platinum Using Me3SiC;C{Pt}Cl (1;Me3SiC;C{Pt} = [Pt(C6H2- successful attachment of 1 toaPh3PAu unit leads to linear + {CH2NMe2}2-2,6-{C;CSiMe3}-4] ) a series of platinum Ph3PAuC;C{Pt}Cl (11). Treatment of 11 with FcC;CSnMe3 monoacetylides of the type XC;C{Pt}C;CR [X = SiMe3: 2, produces the heterotrimetallic rigid-rod shaped complex 5 5 R = Ph; 3,R=(η -C5H4)Fe(η -C5H5) (abbreviated as Fc); 4, Ph3PAuC;C{Pt}C;CFc (13). Cyclic voltammetric studies R=C6H4CN-4; 5,R=C6H4(C;CSnMe3)-4;X=H:7,R=Ph; carried out on these Ph3PAu-capped molecules show that the 8,R=Fc;9,R=C6H4CN-4] have been prepared. Studies attachment of an organometallic entity on either side of the II IV directed towards the coordinative properties of the C2 unit of C;C{Pt} fragment leads to a facilitation of the Pt /Pt oxida- 1 have been carried out and heterotrimetallic [µ- tion. (Me3SiC;C{Pt}Cl][Co2(CO)6](10) could be synthesised. The Introduction The growing interest in the application of organometallic Scheme 1. Precursor complex 1 compounds as building blocks for new materials has led to a large number of publications on their synthesis,[1] and the evaluation of theoretical aspects.[2] In particular, the assem- A useful property of 1 is that it possesses two chemically bly, chemistry, and the physical properties of a number of unique reactive sites.
    [Show full text]
  • Approach and Synthesis of Strychnos Alkaloids
    N° d'ordre : 4155 THÈSE Présentée à L'UNIVERSITÉ BORDEAUX I ÉCOLE DOCTORALE DES SCIENCES CHIMIQUES par Dawood Hosni DAWOOD POUR OBTENIR LE GRADE DE DOCTEUR SPÉCIALITÉ : CHIMIE ORGANIQUE ********************* TOWARDS THE SYNTHESIS OF MONOTERPENOIDS INDOLE ALKALOIDS OF THE ASPIDOSPERMATAN AND STRYCHNAN TYPE ********************* Soutenue le: 17 décembre 2010 Après avis de: MM. PIVA Olivier Professeur, Claude Bernard Lyon 1 Rapporteur PALE Patrick Professeur, Louis Pasteur Strasbourg 1 Rapporteur Devant la commission d'examen formée de : MM. PIVA Olivier Professeur, Claude Bernard Lyon 1 Rapporteur PALE Patrick Professeur, Louis Pasteur Strasbourg 1 Rapporteur POISSON Jean-François Chargé de recherche, CNRS Examinateur VINCENT Jean-Marc Directeur de recherche, CNRS Examinateur LANDAIS Yannick Professeur, Bordeaux 1 Directeur de thèse ROBERT Frédéric Chargé de recherche, CNRS Codirecteur de thèse - 2010 - Abbreviations ∆: reflux °C: celsius degrees Ac: acetyle ALB Aluminium Lithium bis(binaphthoxide) complex AIBN : azobis(isobutyronitrile) aq.: aqueous Ar : aromatic BINAP : 2,2'-bis(diphenylphosphino)-1,1'-binaphthyle BINAPO : 2-diphenylphosphino-2'-diphenylphosphinyl-1,1'-binaphthalene BINOL: 1,1’-bi-2-naphthol Boc: tert-butyloxycarbonyle BOX: Bisoxazoline Bz : benzoyle Bn: benzyle cat. : catalytic DBU: 1,8-diazabicyclo[5.4.0]undec-7-ene DCM: dichloromethane DCC: dicyclohexacarbodiimide dr.: diastereomeric ratio DIBAL-H: diisobutylaluminium hydride DIPEA: diisopropyléthylamine (Hünig Base) DMAP: dimethylaminopyridine DME: dimethoxyethane
    [Show full text]
  • Silver-Catalysed Reactions of Alkynes: Recent Advances
    Chemical Society Reviews Silver -Catalysed Reactions of Alkynes: Recent Advances Journal: Chemical Society Reviews Manuscript ID: CS-REV-01-2015-000027.R2 Article Type: Review Article Date Submitted by the Author: 02-Jun-2015 Complete List of Authors: Fang, Guichun; Northeast Normal University, Department of Chemistry Bi, Xihe; Northeast Normal University, Page 1 of 48Chem Soc Rev Chemical Society Reviews Dynamic Article Links ► Cite this: DOI: 10.1039/c0xx00000x www.rsc.org/ csr CRITICAL REVIEW Silver-Catalysed Reactions of Alkynes: Recent Advances Guichun Fang,a Xihe Bi*a,b Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX DOI: 10.1039/b000000x 5 Silver is a less expensive noble metal. Superior alkynophilicity due to π-coordination with the carbon- carbon triple bond, makes silver salts ideal catalysts for alkyne-based organic reactions. This review highlights the progress in alkyne chemistry via silver catalysis primarily over the past five years (ca. 2010–2014). The discussion is developed in terms of the bond type formed with the acetylenic carbon (i.e. , C–C, C–N, C–O, C–Halo, C–P and C–B). Compared with other coinage metals such as Au and Cu, 10 silver catalysis is frequently observed to be unique. This critical review clearly indicates that silver catalysis provides a significant impetus to the rapid evolution of alkyne-based organic reactions, such as alkynylation, hydrofunctionalization, cycloaddition, cycloisomerization, and cascade reactions. alkynylation, cycloaddition, cycloisomerization of functionalized 1. Introduction alkynes (enynes, multiynes, propargyl compounds, etc. ), and hydrofunctionalization.9 Moreover, in addition to the activation Alkynes and their derivatives are among the most valuable 50 of carbon-carbon triple bonds, other functional groups, such as 15 chemical motifs, because of their abundance and versatile 1 imines and carbonyls are also activated through coordination with reactivities.
    [Show full text]
  • Alkynes and Their Reactions Naming Alkynes • Alkynes Are Named in the Same General Way That Alkenes Are Named
    Alkynes and Their Reactions Naming Alkynes • Alkynes are named in the same general way that alkenes are named. • In the IUPAC system, change the –ane ending of the parent alkane name to the suffix –yne. • Choose the longest continuous chain that contains both atoms of the triple bond and number the chain to give the triple bond the lower number. • Compounds with two triple bonds are named as diynes, those with three are named as triynes and so forth. • Compounds with both a double and triple bond are named as enynes. • The chain is numbered to give the first site of unsaturation (either C=C or C≡C) the lower number. Chapter 11 Preparation of Alkynes Preparation of Alkynes from Alkenes • Alkynes are prepared by elimination reactions. • Since vicinal dihalides are readily made from alkenes, one can convert an alkene • A strong base removes two equivalents of HX from a vicinal to the corresponding alkyne in a or geminal dihalide to yield an alkyne through two successive E2 two-step process involving: elimination reactions. • Halogenation of an alkene. • Double dehydrohalogenation of the resulting vicinal dihalide. • IMPORTANT NOTE: Synthesis of a terminal alkyne by dehydrohalogenation requires 3 equivalents of the base, due to the acidity of the terminal alkyne H H Br 3 equiv. NaNH2 HX Br H2O Terminal Alkynes – Reaction as an Acid Reactions of Alkynide Ions with Alkyl Halides • Terminal alkynes are readily converted to alkynide (acetylide) ions with strong • Acetylide anions are strong nucleophiles and react with unhindered alkyl halides to bases such as NaNH2 and NaH. yield products of nucleophilic substitution.
    [Show full text]
  • Acetylene in Organic Synthesis: Recent Progress and New Uses
    Review Acetylene in Organic Synthesis: Recent Progress and New Uses Vladimir V. Voronin 1, Maria S. Ledovskaya 1, Alexander S. Bogachenkov 1, Konstantin S. Rodygin 1 and Valentine P. Ananikov 1,2,* 1 Institute of Chemistry, Saint Petersburg State University, Universitetsky prospect 26, Peterhof 198504, Russia; [email protected] (V.V.V.); [email protected] (M.S.L.); [email protected] (A.S.B.); [email protected] (K.S.R.) 2 N. D. Zelinsky Institute of Organic Chemistry Russian Academy of Sciences, Leninsky prospect 47, Moscow 119991, Russia * Correspondence: [email protected] Received: 16 August 2018; Accepted: 17 September 2018; Published: 24 September 2018 Abstract: Recent progress in the leading synthetic applications of acetylene is discussed from the prospect of rapid development and novel opportunities. A diversity of reactions involving the acetylene molecule to carry out vinylation processes, cross-coupling reactions, synthesis of substituted alkynes, preparation of heterocycles and the construction of a number of functionalized molecules with different levels of molecular complexity were recently studied. Of particular importance is the utilization of acetylene in the synthesis of pharmaceutical substances and drugs. The increasing interest in acetylene and its involvement in organic transformations highlights a fascinating renaissance of this simplest alkyne molecule. Keywords: acetylene; vinylation; cross-coupling; addition reactions; drugs; pharmaceutical substances; biologically active molecule; monomers; polymers 1. Introduction Since the discovery of acetylene, new areas of acetylene chemistry have been continuously developed. The rich scope of chemical transformations available for a C≡C triple bond can be exemplified by coupling [1–5] and addition reactions [6,7].
    [Show full text]
  • Simulation of Calcium Acetylide and Acetylene Production
    Simulation of calcium acetylide and acetylene production Igor Oršula, Miroslav Lehocký, Pavol Steltenpohl Institute of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, 812 37 Bratislava, Slovakia [email protected] Presented at the 3rd International Conference on Chemical Technology, April 13—15, 2015, Mikulov, Czech Republic: Czech Society of Industrial Chemistry Abstract: Design simulation of a reactor for acetylene production from calcium acetylide and its purification in the gaseous phase is presented. Simulations were performed using the program ASPEN+ which is a very flexible and useful tool for the simulation and optimization of various types of chemical technologies including gas—liquid—solid systems. The first step of the acetylene synthesis, based on coal as the raw material, is the production of calcium acetylide. This substance is obtained from coke and limestone in an electric arc furnace at elevated temperatures. Raw materials used in this process contain relatively large amounts of impurities that are converted and entrapped in the desired product of the above reaction. Some of the impurities, e.g. metallic iron or its alloys, can be separated easily. However, most of the other elements present in the form of their compounds with calcium remain a part of “technical grade” calcium acetylide. Acetylene is commercially produced by the reaction of “technical grade” calcium acetylide with water under controlled reaction conditions in an inert atmosphere. Depending on the purity of calcium acetylide used, the produced raw acetylene contains a variety of admixtures that lower its quality. As a consequence, prior to its expedition to the customer, raw acetylene should be submitted to a down-stream processing that consists of the separation of basic and acidic pollutants present in acetylene by absorption.
    [Show full text]
  • Hazardous Substance Fact Sheet
    Right to Know Hazardous Substance Fact Sheet Common Name: SILVER NITRATE Synonyms: Argerol; Lunar Caustic CAS Number: 7761-88-8 Chemical Name: Nitric Acid Silver (1+) Salt RTK Substance Number: 1672 Date: May 2000 Revision: May 2009 DOT Number: UN 1493 Description and Use EMERGENCY RESPONDERS >>>> SEE LAST PAGE Silver Nitrate is an odorless, colorless or white, crystalline Hazard Summary (sand-like) solid. It is used in photography, medicines, hair Hazard Rating NJDOH NFPA dyes, making mirrors and silver plating, and as a chemical HEALTH 3 - intermediate. FLAMMABILITY 0 - REACTIVITY 0 - CORROSIVE AND STRONG OXIDIZER POISONOUS GASES ARE PRODUCED IN FIRE CONTAINERS MAY EXPLODE IN FIRE Reasons for Citation Hazard Rating Key: 0=minimal; 1=slight; 2=moderate; 3=serious; f Silver Nitrate is on the Right to Know Hazardous Substance 4=severe List because it is cited by OSHA, ACGIH, DOT, NIOSH, DEP and EPA. f Silver Nitrate can affect you when inhaled and by passing f This chemical is on the Special Health Hazard Substance through the skin. List. f Silver Nitrate is CORROSIVE and contact can severely irritate and burn the skin and eyes with possible eye damage. f Inhaling Silver Nitrate can irritate the nose, throat and lungs. f Exposure to Silver Nitrate can cause headache, dizziness, SEE GLOSSARY ON PAGE 5. nausea and vomiting. f High levels of this substance may reduce the blood’s ability to transport Oxygen, causing headache, fatigue, dizziness, FIRST AID and a blue color to the skin and lips (methemoglobinemia). Eye Contact f Repeated exposures to Silver Nitrate can cause blue-gray f Immediately flush with large amounts of water for at least 30 discoloration (argyria) of the eyes, skin, inner nose, mouth, minutes, lifting upper and lower lids.
    [Show full text]
  • Proceedings of the Indiana Academy of Science
    144 Proceedings of Indiana Academy of Science THE SYNTHESIS OF ALKYL ACETYLENES FROM CALCIUM ACETYLIDE Thomas H. Vaughn 1 and James P. Danehy University of Notre Dame Since Lebeau and Picon 2 prepared methylacetylene by the action of sodium acetylide on methyl iodide in liquid ammonia at —45° C. the general equation, HC = CM + RX —-> MX + RC ee CH, has been illustrated by a number of specific reactions, notably by the 3 original invehtigators but also by others . While the alkyl halide has been represented by a large number of combinations of various alkyl 4 groups with chlorine, bromine, iodine and lately the sulphate radical , the metal has been almost exclusively sodium, though occasionally during the last few years potassium has been successfully employed in these laboratories and more recently the alkaline earth acetylides have been used. As early as the end of the last century Moissan 5 prepared the acetylides of lithium, calcium and barium as well as those of sodium and potassium, employing the acetylene to metal method. Moissan, how- ever, considered even the mono-substituted products to be a molecular association of one molecule of carbide and one molecule of acetylene. The acetylide structure, as shown in the above equation, has been as- sumed throughout this work as most easily and simply explaining the observed reactions. Although the action of the alkaline earth metal acetylides would in every way be expected to be analogous to that of sodium and potassium acetylide, this has not heretofore been experimentally verified. This paper reports the action of ethyl sulphate, amyl chloride, and butyl and amyl bromides on calcium acetylide in liquid ammonia.
    [Show full text]