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Dichlorine monoxide
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<h2 id="preparation">Preparation</h2> <p>The earliest method of synthesis was to treat <a href="/facts/Mercury(II)_oxide/uE9xSlQe">mercury(II) oxide</a> with <a href="/facts/Chlorine/y27UwYBM">chlorine</a> gas.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> However, this method is expensive, as well as highly dangerous due to the risk of <a href="/facts/Mercury_poisoning/xdSGkWLU">mercury poisoning</a>. </p> 2 Cl2 + HgO → <a href="/facts/HgCl2/aUAKsq6a">HgCl2</a> + Cl2O <p>A safer and more convenient method of production is the reaction of <a href="/facts/Chlorine/y27UwYBM">chlorine</a> gas with hydrated <a href="/facts/Sodium_carbonate/P6RHvIoK">sodium carbonate</a> at 20–30 °C.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> 2 Cl2 + 2 Na2CO3 + H2O → Cl2O + 2 <a href="/facts/NaHCO3/S9oSol0R">NaHCO3</a> + 2 NaCl 2 Cl2 + 2 <a href="/facts/NaHCO3/S9oSol0R">NaHCO3</a> → Cl2O + 2 CO2 + 2 NaCl + H2O <p>This reaction can be performed in the absence of water but requires heating to 150–250 °C; as dichlorine monoxide is unstable at these temperatures<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> it must therefore be continuously removed to prevent <a href="/facts/Thermal_decomposition/Qqx9RqkW">thermal decomposition</a>. </p> 2 Cl2 + Na2CO3 → Cl2O + CO2 + 2 NaCl <h2 id="structure">Structure</h2> <p>The structure of dichlorine monoxide is similar to that of water and <a href="/facts/Hypochlorous_acid/tGrX1C7z">hypochlorous acid</a>, with the molecule adopting a <a href="/facts/Bent_molecular_geometry/Lf7NzGe2">bent molecular geometry</a> (due to the <a href="/facts/Lone_pair/Q6kEAC4g">lone pairs</a> on the oxygen atom) and resulting in C2V <a href="/facts/Molecular_symmetry/BrDxAkTK">molecular symmetry</a>. The <a href="/facts/Bond_angle/7USG5zDn">bond angle</a> is slightly larger than normal, likely due to <a href="/facts/Steric_repulsion/TnX5c8HG">steric repulsion</a> between the bulky chlorine atoms. </p> <p>In the solid state, it crystallises in the tetrahedral <a href="/facts/Space_group/2XQx0J7M">space group</a> I41/amd, making it isostructural to the high pressure form of water, <a href="/facts/Ice_VIII/gCvRRBgS">ice VIII</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h2 id="reactions">Reactions</h2> <p>Dichlorine monoxide is highly soluble in water,<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> where it exists in an equilibrium with HOCl. The rate of hydrolysis is slow enough to allow the extraction of Cl2O with organic solvents such as <a href="/facts/CCl4/S2ekjT0E">CCl4</a>,<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> but the <a href="/facts/Equilibrium_constant/yMTuuBbX">equilibrium constant</a> ultimately favours the formation of hypochlorous acid.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p> 2 HOCl ⇌ Cl2O + H2O K (0 °C) = 3.55x10−3 dm3/mol <p>Despite this, it has been suggested that dichlorine monoxide may be the active species in the reactions of <a href="/facts/HOCl/tGrX1C7z">HOCl</a> with <a href="/facts/Olefin/RtYcS6kU">olefins</a> and <a href="/facts/Aromatic_compound/3EXq8Tgf">aromatic compounds</a>,<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a><a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> as well as in the chlorination of drinking water.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> </p> <h3>With inorganic compounds</h3> <p>Dichlorine monoxide reacts with <a href="/facts/Metal_halide/6jsbrvcC">metal halides</a>, with the loss of Cl2, to form unusual <a href="/facts/Oxyhalide/vAppA4lU">oxyhalides</a>.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a><a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a><a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> </p> <a href="/facts/VOCl3/I7j4kd7B">VOCl3</a> + Cl2O → VO2Cl + 2 Cl2 <a href="/facts/TiCl4/bGS32SsD">TiCl4</a> + Cl2O → TiOCl2 + 2 Cl2 <a href="/facts/SbCl5/6hfU9lgW">SbCl5</a> + 2 Cl2O → SbO2Cl + 4 Cl2 <p>Similar reactions have also been observed with certain inorganic halides.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a><a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> </p> <a href="/facts/AsCl3/z4ApxBgM">AsCl3</a> + 2 Cl2O → AsO2Cl + 3 Cl2 <a href="/facts/NOCl/TxTff8WH">NOCl</a> + Cl2O → <a href="/facts/NO2Cl/Y1XbBTdf">NO2Cl</a> + Cl2 <h3>With organic compounds</h3> <p>Dichlorine monoxide is an effective chlorinating agent. It can be used for either the side-chain or ring chlorination of deactivated <a href="/facts/Aromatic/wK0DzRY6">aromatic</a> substrates.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> For activated aromatics such as <a href="/facts/Phenol/ACJs5NIU">phenols</a> and aryl-ethers it primarily reacts to give ring halogenated products.<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> It has been suggested that dichlorine monoxide may be the active species in the reactions of <a href="/facts/HOCl/tGrX1C7z">HOCl</a> with <a href="/facts/Olefin/RtYcS6kU">olefins</a> and aromatic compounds.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a><a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> </p> <h3>Photochemistry</h3> <p>Dichlorine monoxide undergoes <a href="/facts/Photodissociation/nzRyzh8I">photodissociation</a>, eventually forming O2 and Cl2. The process is primarily <a href="/facts/Radical_(chemistry)/qFymuVoT">radical</a> based, with <a href="/facts/Flash_photolysis/g9gSdAHr">flash photolysis</a> showing <a href="/facts/Chlorine_monoxide/ajDtLjlS">radical hypochlorite</a> (ClO·) to be a key intermediate.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> </p> 2 Cl2O → 2 Cl2 + O2 <h3>Explosive properties</h3> <p>Dichlorine monoxide is explosive, although there is a lack of modern research into this behaviour. <a href="/facts/Room_temperature/YHwUIUTE">Room temperature</a> mixtures with oxygen could not be detonated by an electric spark until they contained at least 23.5% Cl2O<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> which is an exceedingly high <a href="/facts/Explosive_limit/KkImQKor">minimum explosive limit</a>. There are conflicting reports of it exploding on exposure to strong light.<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a><a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a> Heating above 120 °C, or a rapid rate of heating at lower temperatures also apparently lead to explosions.<a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a> Liquid dichlorine monoxide has been reported to be shock-sensitive.<a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a> </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Balard, A.J. (1834). "Recherches sur la nature des combinaisons décolorantes du chlore" [Investigations into the nature of bleaching compounds of chlorine]. Annales de Chimie et de Physique. 2nd series (in French). 57: 225–304. <a href="https://babel.hathitrust.org/cgi/pt?id=ien.35556014128060;view=1up;seq=230" target="_blank">https://babel.hathitrust.org/cgi/pt?id=ien.35556014128060;view=1up;seq=230</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Renard, J. J.; Bolker, H. I. (1 August 1976). "The chemistry of chlorine monoxide (dichlorine monoxide)". Chemical Reviews. 76 (4): 487–508. doi:10.1021/cr60302a004. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Renard, J. J.; Bolker, H. I. (1 August 1976). "The chemistry of chlorine monoxide (dichlorine monoxide)". Chemical Reviews. 76 (4): 487–508. doi:10.1021/cr60302a004. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Renard, J. J.; Bolker, H. I. (1 August 1976). "The chemistry of chlorine monoxide (dichlorine monoxide)". Chemical Reviews. 76 (4): 487–508. doi:10.1021/cr60302a004. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Hinshelwood, Cyril Norman; Prichard, Charles Ross (1923). "CCCXIII.—A homogeneous gas reaction. The thermal decomposition of chlorine monoxide. Part I". Journal of the Chemical Society, Transactions. 123: 2730–2738. doi:10.1039/CT9232302730. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Minkwitz, R.; Bröchler, R.; Borrmann, H. (1 January 1998). "Tieftemperatur-Kristallstruktur von Dichlormonoxid, Cl2O". Zeitschrift für Kristallographie. 213 (4): 237–239. Bibcode:1998ZK....213..237M. doi:10.1524/zkri.1998.213.4.237. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Davis, D. S. (1942). "Nomograph for the Solubility of Chlorine Monoxide in Water". Industrial & Engineering Chemistry. 34 (5): 624. doi:10.1021/ie50389a021. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Renard, J. J.; Bolker, H. I. (1 August 1976). "The chemistry of chlorine monoxide (dichlorine monoxide)". Chemical Reviews. 76 (4): 487–508. doi:10.1021/cr60302a004. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Aylett, founded by A.F. Holleman; continued by Egon Wiberg; translated by Mary Eagleson, William Brewer; revised by Bernhard J. (2001). Inorganic chemistry (1st English ed., [edited] by Nils Wiberg. ed.). San Diego, Calif. : Berlin: Academic Press, W. de Gruyter. p. 442. ISBN 9780123526519.{{cite book}}: CS1 maint: multiple names: authors list (link) <a href="9780123526519" target="_blank">9780123526519</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Swain, C. Gardner; Crist, DeLanson R. (1 May 1972). "Mechanisms of chlorination by hypochlorous acid. The last of chlorinium ion, Cl+". Journal of the American Chemical Society. 94 (9): 3195–3200. doi:10.1021/ja00764a050. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Sivey, John D.; McCullough, Corey E.; Roberts, A. Lynn (1 May 2010). "Chlorine Monoxide (Cl2O) and Molecular Chlorine (Cl2) as Active Chlorinating Agents in Reaction of Dimethenamid with Aqueous Free Chlorine". Environmental Science & Technology. 44 (9): 3357–3362. Bibcode:2010EnST...44.3357S. doi:10.1021/es9038903. PMID 20302364. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Powell, Steven C. (1 May 2010). "The active species in drinking water chlorination: the case for Cl2O". Environmental Science & Technology. 44 (9): 3203. Bibcode:2010EnST...44.3203P. doi:10.1021/es100800t. PMID 20302368. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Oppermann, H. (1967). "Untersuchungen an Vanadinoxidchloriden und Vanadinchloriden. I. Gleichgewichte mit VOCl3, VO2Cl und VOCl2". Zeitschrift für anorganische und allgemeine Chemie. 351 (3–4): 113–126. doi:10.1002/zaac.19673510302. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Dehnicke, Kurt (1961). "Titan(IV)-Oxidchlorid TiOCl2". Zeitschrift für anorganische und allgemeine Chemie. 309 (5–6): 266–275. doi:10.1002/zaac.19613090505. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Renard, J. J.; Bolker, H. I. (1 August 1976). "The chemistry of chlorine monoxide (dichlorine monoxide)". Chemical Reviews. 76 (4): 487–508. doi:10.1021/cr60302a004. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Dehnicke, Kurt (1 December 1964). "Über die Oxidchloride PO2Cl, AsO2Cl und SbO2Cl". Chemische Berichte. 97 (12): 3358–3362. doi:10.1002/cber.19640971215. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Martin, H. (1 January 1966). "Kinetic Relationships between Reactions in the Gas Phase and in Solution". Angewandte Chemie International Edition in English. 5 (1): 78–84. doi:10.1002/anie.196600781. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Marsh, F. D.; Farnham, W. B.; Sam, D. J.; Smart, B. E. (1 August 1982). "Dichlorine monoxide: a powerful and selective chlorinating reagent". Journal of the American Chemical Society. 104 (17): 4680–4682. doi:10.1021/ja00381a032. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Sivey, John D.; Roberts, A. Lynn (21 February 2012). "Assessing the Reactivity of Free Chlorine Constituents Cl2, Cl2O, and HOCl Toward Aromatic Ethers". Environmental Science & Technology. 46 (4): 2141–2147. Bibcode:2012EnST...46.2141S. doi:10.1021/es203094z. PMID 22211432. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>Swain, C. Gardner; Crist, DeLanson R. (1 May 1972). "Mechanisms of chlorination by hypochlorous acid. The last of chlorinium ion, Cl+". Journal of the American Chemical Society. 94 (9): 3195–3200. doi:10.1021/ja00764a050. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>Sivey, John D.; McCullough, Corey E.; Roberts, A. Lynn (1 May 2010). "Chlorine Monoxide (Cl2O) and Molecular Chlorine (Cl2) as Active Chlorinating Agents in Reaction of Dimethenamid with Aqueous Free Chlorine". Environmental Science & Technology. 44 (9): 3357–3362. Bibcode:2010EnST...44.3357S. doi:10.1021/es9038903. PMID 20302364. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>Basco, N.; Dogra, S. K. (22 June 1971). "Reactions of Halogen Oxides Studied by Flash Photolysis. II. The Flash Photolysis of Chlorine Monoxide and of the ClO Free Radical". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 323 (1554): 401–415. Bibcode:1971RSPSA.323..401B. doi:10.1098/rspa.1971.0112. S2CID 98084403. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>Cady, George H.; Brown, Robert E. (September 1945). "Minimum Explosive Concentration of Chlorine Monoxide Diluted with Oxygen". Journal of the American Chemical Society. 67 (9): 1614–1615. doi:10.1021/ja01225a501. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>Iredale, T.; Edwards, T. G. (April 1937). "Photoreaction of Chlorine Monoxide and Hydrogen". Journal of the American Chemical Society. 59 (4): 761. doi:10.1021/ja01283a504. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> <li id="fn:25"><p>Wallace, Janet I.; Goodeve, C. F. (1 January 1931). "The heats of dissociation of chlorine monoxide and chlorine dioxide". Transactions of the Faraday Society. 27: 648. doi:10.1039/TF9312700648. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></p></li> <li id="fn:26"><p>Renard, J. J.; Bolker, H. I. (1 August 1976). "The chemistry of chlorine monoxide (dichlorine monoxide)". Chemical Reviews. 76 (4): 487–508. doi:10.1021/cr60302a004. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:26" class="footnote-back-ref">↩</a></p></li> <li id="fn:27"><p>Pilipovich, Donald; Lindahl, C. B.; Schack, Carl J.; Wilson, R. D.; Christe, Karl O. (1972). "Chlorine trifluoride oxide. I. Preparation and properties". Inorganic Chemistry. 11 (9): 2189–2192. doi:10.1021/ic50115a040. ISSN 0020-1669. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></p></li> </ol>