Copper(I) acetylide

<h2 id="synthesis">Synthesis</h2>
Materials purported to be copper acetylide can be prepared by treating <a href="/facts/Acetylene/yaDh6cmJ">acetylene</a> with a solution of <a href="/facts/Copper(I)_chloride/L8RgsAhF">copper(I) chloride</a> and <a href="/facts/Ammonia/MtLtJFtz">ammonia</a>:

C2H2(<a href="/facts/Gas/hVVAoodV">g</a>) + 2 CuCl(<a href="/facts/Solid/hj5UsXno">s</a>) → Cu2C2(s) + 2 <a href="/facts/Hydrogen_chloride/7Wzkhomd">HCl</a>(g)
This reaction produces a reddish solid <a href="/facts/Precipitate/s3BgsLLY">precipitate</a>.

<h2 id="properties">Properties</h2>
When dry, copper acetylide is a heat and shock sensitive <a href="/facts/Primary_explosive/sUme5Pp8">primary explosive</a>, more sensitive than <a href="/facts/Silver_acetylide/oMMH64lA">silver acetylide</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2">2</a>
In acetylene manufacturing plants, copper acetylide is thought to form inside pipes made of <a href="/facts/Copper/I8PEE8oX">copper</a> or an alloy with high copper content, which may result in violent explosion.<a class="footnote-ref" id="fnref:3" href="#fn:3">3</a> This led to abandonment of copper as a construction material in such facilities.<a class="footnote-ref" id="fnref:4" href="#fn:4">4</a> Copper <a href="/facts/Catalyst/LPBS7TQC">catalysts</a> used in the <a href="/facts/Chemical_industry/3M6gfHer">chemical industry</a> can also possess a degree of risk under certain conditions.<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a>

<h2 id="reactions">Reactions</h2>
Copper(I) acetylide is the substrate of <a href="/facts/Glaser_coupling/n68cQ7r7">Glaser coupling</a> for the formation of <a href="/facts/Polyyne/ReohbKe8">polyynes</a>. In a typical reaction, a suspension of Cu2C2·H2O in an <a href="/facts/Ammonium/jYm8wc1n">amoniacal</a> solution is treated with air. The copper is <a href="/facts/Oxidized/Pyd5RVcj">oxidized</a> to Cu2+ and forms a blue soluble <a href="/facts/Coordination_compound/1tCyeQUm">complex</a> with the <a href="/facts/Ammonia/MtLtJFtz">ammonia</a>, leaving behind a black solid residue. The latter has been claimed to consist of <a href="/facts/Linear_acetylenic_carbon/b5ebrE1J">carbyne</a>, an elusive <a href="/facts/Allotrope/2WUdHWxg">allotrope</a> of carbon:<a class="footnote-ref" id="fnref:6" href="#fn:6">6</a>

Cu+(−C(≡C−C≡)nC−)Cu+
This interpretation has been disputed.<a class="footnote-ref" id="fnref:7" href="#fn:7">7</a>
Freshly prepared copper(I) acetylide reacts with <a href="/facts/Hydrochloric_acid/HqItJlUT">hydrochloric acid</a> to form acetylene and copper(I) chloride. Samples that have been aged with exposure to air or to copper(II) ions liberate also higher <a href="/facts/Polyyne/ReohbKe8">polyynes</a> H(−C≡C−)nH, with n from 2 to 6, when decomposed by <a href="/facts/Hydrochloric_acid/HqItJlUT">hydrochloric acid</a>. 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 <a href="/facts/Acetylide/3u0EMxz3">acetylide</a> anions C2−2 in the solid into <a href="/facts/Linear_acetylenic_carbon/b5ebrE1J">carbyne</a>-type anions. −C(≡C−C≡)nC− or <a href="/facts/Cumulene/UtxYSvxN">cumulene</a>-type anions 2−C(=C=C=)nC2−.<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a>
<a href="/facts/Thermal_decomposition/Qqx9RqkW">Thermal decomposition</a> of copper(I) 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 <a href="/facts/Linear_acetylenic_carbon/b5ebrE1J">carbyne</a> (−C≡C−)n rather than <a href="/facts/Graphite/sSf3KMXr">graphite</a> as expected.<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a>

<h2 id="applications">Applications</h2>
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(I) acetylide when a gas is passed through a solution of <a href="/facts/Copper(I)_chloride/L8RgsAhF">copper(I) chloride</a> is used as a test for the presence of <a href="/facts/Acetylene/yaDh6cmJ">acetylene</a>.
Reactions between Cu+ and <a href="/facts/Alkynes/VHI4N5Wo">alkynes</a> occur only if a terminal <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a> is present (as it is slightly <a href="/facts/Acidic/FySU18n1">acidic</a> in nature). Thus, this reaction is used for identification of terminal alkynes.

<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Carbide/xfCMTjYJ">Carbide</a></li>
<li><a href="/facts/Walter_Reppe/ymWkKRod">Walter Reppe</a></li>
<li><a href="/facts/Alkynation/qdSslHPC">Ethynylation</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1">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 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">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. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">"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. <a href="https://web.archive.org/web/20080706064005/http://www.msha.gov/Accident_Prevention/Tips/acetylenegas.htm" target="_blank">https://web.archive.org/web/20080706064005/http://www.msha.gov/Accident_Prevention/Tips/acetylenegas.htm</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">"Copper". Archived from the original on October 1, 2007. Retrieved February 8, 2013. <a href="https://web.archive.org/web/20071001010729/http://www.ilo.org/encyclopedia/?print&nd=857200158" target="_blank">https://web.archive.org/web/20071001010729/http://www.ilo.org/encyclopedia/?print&nd=857200158</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">"The Safe Use of Copper -Containing Catalysts in Ethylene Plants". Retrieved 2008-06-08. <a href="http://aiche.confex.com/aiche/s06/preliminaryprogram/abstract_43768.htm" target="_blank">http://aiche.confex.com/aiche/s06/preliminaryprogram/abstract_43768.htm</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">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 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">H. Kroto (2010), Carbyne and other myths about carbon. RSC Chemistry World, November 2010. <a href="http://www.rsc.org/chemistryworld/Issues/2010/November/CarbyneOtherMythsAboutCarbon.asp" target="_blank">http://www.rsc.org/chemistryworld/Issues/2010/November/CarbyneOtherMythsAboutCarbon.asp</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">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 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
<li id="fn:9">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 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></li>
</ol>

Copper(I) acetylide open-in-new

Copper(I) acetylide