What is Calcium Acetylide?

Information about Calcium Acetylide

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The general structure of a metal acetylide
A metal acetylide is an alkyne for which the terminal proton (hydrogen) has been replaced by a metal such as sodium or an organolithium. So, for example, the alkyne CH3C≡CH could be deprotonated to form the acetylide ion CH3C≡C−. Once it has been deprotonated it becomes a strong nucleophile. Some acetylides, eg. silver acetylide or copper acetylide, are explosives.

Acetylide ions are very useful in organic chemistry reactions in combining carbon chains, particularly addition and substitution reactions. One type of reaction displayed by acetylides are addition reactions with ketones to form tertiary alcohols. In the reaction in scheme 1 the alkyne proton of ethyl propiolate is deprotonated by n-butyllithium at -78°C to form lithium ethyl propiolate to which cyclopentanone is added forming a lithium alkoxide. Acetic acid is added to remove lithium and liberate the free alcohol.[1]

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Scheme 1. Reaction of ethyl propiolate with n-butyllithium to form the lithium acetylide.


Coupling reactions of alkynes like the Sonogashira coupling, the Cadiot-Chodkiewicz coupling, the Glaser coupling and the Eglinton coupling often have metal acetylides as intermediates.

Several modifications of the reaction with carbonyls are known:
  • In the Arens-van Dorp Synthesis the compound ethoxyacetylene [2] is converted to a Grignard reagent and reacted with a ketone, the reaction product is a propargyl alcohol [3].
  • In the Isler modification ethoxyacetylene is replaced by beta-chlorovinyl ether and lithium amide.
  • In the Favorskii-Babayan synthesis ketones and acetylenic compounds react in presence of alkali [4].
Formation of acetylides poses a risk in handling of gaseous acetylene in presence of metals such as mercury, silver or copper, or alloys with their high content (brass, bronze, silver solder).

References

1. ^ Synthesis of alkyl 4-hydroxy-2-alkynoates M. Mark Midland, Alfonso Tramontano, John R. Cable J. Org. Chem.; 1980; 45(1); 28-29. Abstract
2. ^ Organic Syntheses, Coll. Vol. 4, p.404 (1963); Vol. 34, p.46 (1954). Link
3. ^ van Dorp and Arens, Nature, 160, 189 (1947).
4. ^ [1]
Alkynes are hydrocarbons that have at least one triple bond between two carbon atoms, with the formula CnH2n-2. The alkynes are traditionally known as acetylenes or the acetylene series, although the name acetylene
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Sodium (IPA: /ˈsəʊdiəm/) is a chemical element which has the symbol Na (Latin: natrium), atomic number 11, atomic mass 22.9898 g/mol, common oxidation number +1.
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An organolithium reagent is an organometallic compound with a direct bond between a carbon and a lithium atom. As the electropositive nature of lithium puts most of the charge density of the bond on the carbon atom, effectively creating a carbanion, organolithium compounds are
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Deprotonation is a chemistry term that refers to the removal of a hydron (hydrogen ion H+) from a molecule, forming the conjugate base. The relative ability for a molecule to give up a proton is measured by a pKa value.
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In chemistry, a nucleophile (literally nucleus lover as in nucleus and phile) is a reagent that forms a chemical bond to its reaction partner (the electrophile) by donating both bonding electrons.
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Silver acetylide is an inorganic chemical compound with the formula Ag2C2, a metal acetylide. The name derived from the way it is synthesized, the alternative silver carbide is not used in literature, although the substance is similar to calcium carbide .
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Copper(I) acetylide, or cuprous acetylide, is an inorganic chemical compound with the formula Cu2C2. It is a heat and shock sensitive high explosive, more sensitive than silver acetylide. It is a metal acetylide.
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explosive material is a material that either is chemically or otherwise energetically unstable or produces a sudden expansion of the material usually accompanied by the production of heat and large changes in pressure (and typically also a flash and/or loud noise) upon initiation;
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An addition reaction, in chemistry, is in its simplest terms an organic reaction where two or more molecules combine to form a larger one.

There are two main types of polar addition reactions:
  • Electrophilic addition
  • Nucleophilic addition

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In a substitution reaction, a functional group in a particular chemical compound is replaced by another group.

In organic chemistry, the electrophilic and nucleophilic substitution reactions are of prime importance.
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An addition reaction, in chemistry, is in its simplest terms an organic reaction where two or more molecules combine to form a larger one.

There are two main types of polar addition reactions:
  • Electrophilic addition
  • Nucleophilic addition

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A ketone (pronounced as key tone) is either the functional group characterized by a carbonyl group (O=C) linked to two other carbon atoms or a chemical compound that contains this functional group.
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alcohol is any organic compound in which a hydroxyl group (-OH) is bound to a carbon atom of an alkyl or substituted alkyl group. The general formula for a simple acyclic alcohol is CnH2n+1OH.
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Cyclopentanone is a colorless liquid organic compound with a peppermint-like odor. It is a cyclic ketone, structurally similar to cyclopentane, consisting of a five-membered ring containing a ketone functional group.
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In chemistry, the alkoxyl group is an alkyl group linked to oxygen thus: R-O. The range of alkoxy groups is as great, the simplest being methoxy (-OCH3). An ethoxy substituent is found in the organic compound phenetol, C6H5OCH2CH
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Acetic acid, also known as ethanoic acid, is an organic chemical compound best recognized for giving vinegar its sour taste and pungent smell. Its structural formula is represented as CH3COOH.
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In organic chemistry, a Sonogashira coupling is a coupling reaction of terminal alkynes with aryl or vinyl halides. This reaction was first reported by Kenkichi Sonogashira and Nobue Hagihara in 1975.
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The Cadiot-Chodkiewicz coupling in organic chemistry is a coupling reaction between a terminal alkyne and a haloalkyne catalyzed by a copper(I) salt such as copper(I) bromide and an amine base [1] [2]. The reaction product is a di-acetylene or di-alkyne.
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The Grignard reaction, named for the French chemist François Auguste Victor Grignard, is an organometallic chemical reaction involving alkyl- or aryl-magnesium halides, also called Grignard reagents, with electrophiles.
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Lithium amide is an inorganic compound with the chemical formula Li+NH2-, i.e. it is composed of a lithium cation, and the conjugate base of ammonia. It is a white solid with a tetragonal crystal structure.
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alkali (from Arabic: Al-Qalyالقلي, القالي ) is a basic, ionic salt of an alkali metal or alkaline earth metal element.
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2, 1
(mildly basic oxide)
Electronegativity 2.00 (scale Pauling)
Ionization energies 1st: 1007.1 kJ/mol
2nd: 1810 kJ/mol
3rd: 3300 kJ/mol
Atomic radius 150 pm
Atomic radius (calc.
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Silver (IPA: /ˈsɪlvə(ɹ)/) is a chemical element with the symbol Ag (Latin: argentum) and atomic number 47.
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2, 1
(mildly basic oxide)
Electronegativity 1.90 (Pauling scale)
Ionization energies
(more) 1st: 745.5 kJmol−1
2nd: 1957.9 kJmol−1
3rd: 3666 kJmol−1

Atomic radius 135 pm
Atomic radius (calc.
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