World Library  
Flag as Inappropriate
Email this Article

Copper(I) acetylide

Article Id: WHEBN0008620994
Reproduction Date:

Title: Copper(I) acetylide  
Author: World Heritage Encyclopedia
Language: English
Subject: Potassium hexafluorocuprate(III), Linear acetylenic carbon, Carbide, Copper(II) azide, Copper(II) tetrafluoroborate
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Copper(I) acetylide

Copper(I) acetylide
Identifiers
CAS number  YesY
PubChem
Jmol-3D images Image 1
Properties
Molecular formula C2Cu2
Molar mass 151.11 g mol−1
Hazards
Main hazards Explosive, Harmful
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY   YesY/N?)

Copper(I) acetylide, or cuprous acetylide, is a chemical compound with the formula Cu2C2, known at least since 1856.[1] In the common form (a monohydrate with formula Cu
2
C
2
.H
2
O
) it is a reddish solid, that easily explodes when dry.

Structure

Copper acetylide is a metal acetylide, a salt of the acetylide anion C2−
2
and the copper(I) cation Cu+
. It is similar to silver acetylide and calcium carbide, though it is not called carbide in literature.

Synthesis

Copper acetylide can be prepared by passing acetylene gas through copper(I) chloride solution in the presence of ammonia:

C2H2 + 2CuCl → Cu2C2 + 2HCl

The acetylide then separates as a reddish precipitate.

Properties

When dry, copper acetylide is a heat and shock sensitive high explosive, more sensitive than silver acetylide.

Copper acetylide can form inside pipes made of copper or an alloy with high copper content, which may result in violent explosion.[2] This was found to be the cause of explosions in acetylene plants, and led to abandonment of copper as a construction material in such plants.[3] Copper catalysts used in petrochemistry can also possess a degree of risk under certain conditions.[4]

Reactions

Copper acetylide is the substrate of Glaser's reaction for the formation of polyynes. In a typical reaction, air is bubbled through a suspension of Cu
2
C
2
.H
2
O
in an amoniacal solution. The copper is oxidized to Cu2+
and forms a blue soluble complex with the ammonium species, leaving behind a black solid residue. The latter has been claimed to consist of carbyne, an elusive allotrope of carbon;[5] more precisely of "polyacetylyde" anions capped with residual copper(I) ions,

Cu+
C(≡C−C≡)nC Cu+

However that interpretation has been disputed.[6]

Freshly prepared copper acetylide is decomposed by hydrochloric acid into 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−.[1]

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.[1]

Applications

Though not practically useful as an explosive due to high sensitivity and reactivity towards water, 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.

The reaction of Cu+ with alkyne occurs only if terminal hydrogen is present (as it is slight acidic in nature). Thus this reaction is used for identifification of terminal alkynes.

See also

References

  1. ^ a b c 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
  2. ^ "Mine Safety and Health Administration (MSHA) - Accident Prevention Program - Miner's Tips - Hazards of Acetylene Gas". Retrieved 2008-06-08. 
  3. ^ [1]
  4. ^ "The Safe Use of Copper -Containing Catalysts in Ethylene Plants". Retrieved 2008-06-08. 
  5. ^ 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
  6. ^ H. Kroto (2010), Carbyne and other myths about carbon. RSC Chemistry World, November 2010.
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 



Copyright © World Library Foundation. All rights reserved. eBooks from World Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.