Copper(I) acetylide

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Copper(I) acetylide
Copper acetylide.png
Names
IUPAC name
Dicuprous acetylide
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
  • InChI=1S/C2.2Cu/c1-2;;/q-2;2*+1 X mark.svgN
    Key: SQDLRJMJSRRYGA-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C2.2Cu/c1-2;;/q-2;2*+1
    Key: SQDLRJMJSRRYGA-UHFFFAOYAK
  • [C-]#[C-].[Cu+].[Cu+]
Properties
C2Cu2
Molar mass 151.114 g·mol−1
Appearancered-brown powder
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
explosive
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 1 mg/m3 (as Cu) [1]
REL (Recommended)
TWA 1 mg/m3 (as Cu) [1]
IDLH (Immediate danger)
TWA 100 mg/m3 (as Cu) [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Copper(I) acetylide, Kupfercarbid or cuprous acetylide, is a chemical compound with the formula Cu 2 C 2. Although never characterized by X-ray crystallography, the material has been claimed at least since 1856. [2] One form is claimed to be a monohydrate with formula Cu
2
C
2
.H
2
O
is a reddish-brown explosive powder.

Contents

Synthesis

Materials purported to be copper acetylide can be prepared by treating acetylene with a solution of copper(I) chloride and ammonia:

C2H2 (g) + 2 CuCl (s) → Cu2C2 (s) + 2 HCl (g)

This reaction produces a reddish solid precipitate.

Properties

When dry, copper acetylide is a heat and shock sensitive primary explosive, more sensitive than silver acetylide. [3]

In acetylene manufacturing plants, copper acetylide is thought to form inside pipes made of copper or an alloy with high copper content, which may result in violent explosion. [4] This led to abandonment of copper as a construction material in such facilities. [5] Copper catalysts used in the chemical industry can also possess a degree of risk under certain conditions. [6]

Reactions

Copper acetylide is the substrate of Glaser coupling for the formation of polyynes. In a typical reaction, a suspension of Cu
2
C
2
.H
2
O
in an amoniacal solution is treated with air. The copper is oxidized to Cu2+
and forms a blue soluble complex with the ammonia, leaving behind a black solid residue. The latter has been claimed to consist of carbyne, an elusive allotrope of carbon: [7]

Cu+
C(≡C−C≡)nCCu+

This interpretation has been disputed. [8]

Freshly prepared copper acetylide reacts with hydrochloric acid to form acetylene and copper(I) chloride. Samples that have been aged with exposure to air or to copper(II) ions liberate also higher polyynes H(−C≡C−)nH, with n from 2 to 6, when decomposed by hydrochloric acid. A "carbonaceous" residue of this decomposition also has the spectral signature of (−C≡C−)n chains. It has been conjectured that oxidation causes polymerization of the acetylide anions C2−
2
in the solid into carbyne-type anions .C(≡C−C≡)nC2− or polycumulene-type anions C(=C=C=)mC4−. [2]

Thermal decomposition of copper acetylide in vacuum is not explosive and leaves copper as a fine powder at the bottom of the flask, while depositing a fluffy very fine carbon powder on the walls. On the basis of spectral data, this powder was claimed to be carbyne C(−C≡C−)nC rather than graphite as expected. [2]

Applications

Though not practically useful as an explosive due to high sensitivity, it is interesting as a curiosity because it is one of the very few explosives that do not liberate any gaseous products upon detonation.

The formation of copper acetylide when a gas is passed through a solution of copper(I) chloride is used as a test for the presence of acetylene.

Reactions between Cu+ and alkynes occur only if a terminal hydrogen is present (as it is slightly acidic in nature). Thus, this reaction is used for identification of terminal alkynes.

See also

Related Research Articles

<span class="mw-page-title-main">Acetylene</span> Hydrocarbon compound (HC≡CH)

Acetylene is the chemical compound with the formula C2H2 and structure H−C≡C−H. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution. Pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities such as divinyl sulfide and phosphine.

<span class="mw-page-title-main">Alkyne</span> Hydrocarbon compound containing one or more C≡C bonds

In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula CnH2n−2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature. Like other hydrocarbons, alkynes are generally hydrophobic.

In organometallic chemistry, acetylide refers to chemical compounds with the chemical formulas MC≡CH and MC≡CM, where M is a metal. The term is used loosely and can refer to substituted acetylides having the general structure RC≡CM. Acetylides are reagents in organic synthesis. The calcium acetylide commonly called calcium carbide is a major compound of commerce.

The Sonogashira reaction is a cross-coupling reaction used in organic synthesis to form carbon–carbon bonds. It employs a palladium catalyst as well as copper co-catalyst to form a carbon–carbon bond between a terminal alkyne and an aryl or vinyl halide.

<span class="mw-page-title-main">Copper(I) chloride</span> Chemical compound

Copper(I) chloride, commonly called cuprous chloride, is the lower chloride of copper, with the formula CuCl. The substance is a white solid sparingly soluble in water, but very soluble in concentrated hydrochloric acid. Impure samples appear green due to the presence of copper(II) chloride (CuCl2).

The azide-alkyne Huisgen cycloaddition is a 1,3-dipolar cycloaddition between an azide and a terminal or internal alkyne to give a 1,2,3-triazole. Rolf Huisgen was the first to understand the scope of this organic reaction. American chemist Karl Barry Sharpless has referred to this cycloaddition as "the cream of the crop" of click chemistry and "the premier example of a click reaction".

<span class="mw-page-title-main">Chromium(III) oxide</span> Chemical compound

Chromium(III) oxide is an inorganic compound with the formula Cr
2
O
3
. It is one of the principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite.

<span class="mw-page-title-main">Copper(I) iodide</span> Chemical compound

Copper(I) iodide is the inorganic compound with the formula CuI. It is also known as cuprous iodide. It is useful in a variety of applications ranging from organic synthesis to cloud seeding.

<span class="mw-page-title-main">Polyyne</span> Any organic compound with alternating C–C and C≡C bonds

A polyyne is any organic compound with alternating single and triple bonds; that is, a series of consecutive alkynes, (−C≡C−)n with n greater than 1. These compounds are also called polyacetylenes, especially in the natural products and chemical ecology literature, even though this nomenclature more properly refers to acetylene polymers composed of alternating single and double bonds (−CR=CR′−)n with n greater than 1. They are also sometimes referred to as oligoynes, or carbinoids after "carbyne" (−C≡C−), the hypothetical allotrope of carbon that would be the ultimate member of the series. The synthesis of this substance has been claimed several times since the 1960s, but those reports have been disputed. Indeed, the substances identified as short chains of "carbyne" in many early organic synthesis attempts would be called polyynes today.

Chaoite, or white carbon, is a mineral described as an allotrope of carbon whose existence is disputed. It was discovered in shock-fused graphite gneiss from the Ries crater in Bavaria. It has been described as slightly harder than graphite, with a reflection colour of grey to white. From its electron diffraction pattern, the mineral has been considered to have a carbyne structure, the linear acetylenic carbon allotrope of carbon. A later report has called this identification, and the very existence of carbyne phases, into question, arguing that the new reflections in the diffraction pattern are due to clay impurities.

<span class="mw-page-title-main">Trimethylsilyl chloride</span> Organosilicon compound with the formula (CH3)3SiCl

Trimethylsilyl chloride, also known as chlorotrimethylsilane is an organosilicon compound, with the formula (CH3)3SiCl, often abbreviated Me3SiCl or TMSCl. It is a colourless volatile liquid that is stable in the absence of water. It is widely used in organic chemistry.

In organic chemistry, a cycloalkyne is the cyclic analog of an alkyne. A cycloalkyne consists of a closed ring of carbon atoms containing one or more triple bonds. Cycloalkynes have a general formula CnH2n−4. Because of the linear nature of the C−C≡C−C alkyne unit, cycloalkynes can be highly strained and can only exist when the number of carbon atoms in the ring is great enough to provide the flexibility necessary to accommodate this geometry. Large alkyne-containing carbocycles may be virtually unstrained, while the smallest constituents of this class of molecules may experience so much strain that they have yet to be observed experimentally. Cyclooctyne is the smallest cycloalkyne capable of being isolated and stored as a stable compound. Despite this, smaller cycloalkynes can be produced and trapped through reactions with other organic molecules or through complexation to transition metals.

<span class="mw-page-title-main">Arsenic trichloride</span> Chemical compound

Arsenic trichloride is an inorganic compound with the formula AsCl3, also known as arsenous chloride or butter of arsenic. This poisonous oil is colourless, although impure samples may appear yellow. It is an intermediate in the manufacture of organoarsenic compounds.

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. The reaction product is a 1,3-diyne or di-alkyne.

<span class="mw-page-title-main">Silver compounds</span> Chemical compounds containing silver

Silver is a relatively unreactive metal, although it can form several compounds. The common oxidation states of silver are (in order of commonness): +1 (the most stable state; for example, silver nitrate, AgNO3); +2 (highly oxidising; for example, silver(II) fluoride, AgF2); and even very rarely +3 (extreme oxidising; for example, potassium tetrafluoroargentate(III), KAgF4). The +3 state requires very strong oxidising agents to attain, such as fluorine or peroxodisulfate, and some silver(III) compounds react with atmospheric moisture and attack glass. Indeed, silver(III) fluoride is usually obtained by reacting silver or silver monofluoride with the strongest known oxidizing agent, krypton difluoride.

<span class="mw-page-title-main">Organocopper chemistry</span> Compound with carbon to copper bonds

Organocopper chemistry is the study of the physical properties, reactions, and synthesis of organocopper compounds, which are organometallic compounds containing a carbon to copper chemical bond. They are reagents in organic chemistry.

The Castro–Stephens coupling is a cross coupling reaction between a copper(I) acetylide and an aryl halide in pyridine, forming a disubstituted alkyne and a copper(I) halide.

The Glaser coupling is a type of coupling reaction. It is by far the oldest acetylenic coupling and is based on cuprous salts like copper(I) chloride or copper(I) bromide and an additional oxidant like oxygen. The base in its original scope is ammonia. The solvent is water or an alcohol. The reaction was first reported by Carl Andreas Glaser in 1869. He suggested the following process for his way to diphenylbutadiyne:

<span class="mw-page-title-main">Linear acetylenic carbon</span> Polymer made of repeating −C≡C− units

Linear acetylenic carbon (LAC), also known as carbyne or Linear Carbon Chain (LCC), is an allotrope of carbon that has the chemical structure (−C≡C−)n as a repeat unit, with alternating single and triple bonds. It would thus be the ultimate member of the polyyne family.

In organometallic chemistry, a transition metal alkyne complex is a coordination compound containing one or more alkyne ligands. Such compounds are intermediates in many catalytic reactions that convert alkynes to other organic products, e.g. hydrogenation and trimerization.

References

  1. 1 2 3 NIOSH Pocket Guide to Chemical Hazards. "#0150". National Institute for Occupational Safety and Health (NIOSH).
  2. 1 2 3 Franco Cataldo (1999), From dicopper acetylide to carbyne.Polymer International, volume 48, issue 1, pages 15-22. doi : 10.1002/(SICI)1097-0126(199901)48:1
  3. Cataldo, Franco; Casari, Carlo S. (2007). "Synthesis, Structure and Thermal Properties of Copper and Silver Polyynides and Acetylides". Journal of Inorganic and Organometallic Polymers and Materials. 17 (4): 641–651. doi:10.1007/s10904-007-9150-3. ISSN   1574-1443. S2CID   96278932.
  4. "Mine Safety and Health Administration (MSHA) - Accident Prevention Program - Miner's Tips - Hazards of Acetylene Gas". Archived from the original on 2008-07-06. Retrieved 2008-06-08.
  5. "Copper". Archived from the original on October 1, 2007. Retrieved February 8, 2013.
  6. "The Safe Use of Copper -Containing Catalysts in Ethylene Plants" . Retrieved 2008-06-08.
  7. Franco Cataldo (1999), ' 'A study on the structure and electrical properties of the fourth carbon allotrope: carbyne. Polymer International, volume 44, issue 2, pages 191–200. doi : 10.1002/(SICI)1097-0126(199710)44:2
  8. H. Kroto (2010), Carbyne and other myths about carbon. RSC Chemistry World, November 2010.