Organic azide

<h2 id="history">History</h2>
<a href="/facts/Phenyl_azide/tczBhkqK">Phenyl azide</a> ("diazoamidobenzol"), was prepared in 1864 by <a href="/facts/Peter_Griess/6ksmURVu">Peter Griess</a> by the reaction of ammonia and <a href="/facts/Phenyldiazonium/I1Mxu1cx">phenyldiazonium</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2">2</a><a class="footnote-ref" id="fnref:3" href="#fn:3">3</a> In the 1890s, <a href="/facts/Theodor_Curtius/z4VbyR9u">Theodor Curtius</a>, who had discovered <a href="/facts/Hydrazoic_acid/rbtF5smp">hydrazoic acid</a> (HN3), described the rearrangement of acyl azides to isocyanates subsequently named the <a href="/facts/Curtius_rearrangement/ubsp6a7E">Curtius rearrangement</a>.<a class="footnote-ref" id="fnref:4" href="#fn:4">4</a> <a href="/facts/Rolf_Huisgen/kHH3WAyv">Rolf Huisgen</a> described the eponymous <a href="/facts/1%2c3-dipolar_cycloaddition/DNyagu07">1,3-dipolar cycloaddition</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a><a class="footnote-ref" id="fnref:6" href="#fn:6">6</a>
The interest in azides among organic chemists has been relatively modest due to the reported <a href="/facts/Instability/V0uNz1oI">instability</a> of these compounds.<a class="footnote-ref" id="fnref:7" href="#fn:7">7</a> The situation has changed dramatically with the discovery by Sharpless et al. of Cu-catalysed (3+2)-cycloadditions between organic azides and terminal alkynes.<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a><a class="footnote-ref" id="fnref:9" href="#fn:9">9</a> The azido- and the alkyne groups are "<a href="/facts/Bioorthogonal_chemistry/ymFknJQC">bioorthogonal</a>", which means they do not interact with living systems, and at the same time they undergo an impressively fast and selective coupling. This type of formal 1,3-dipolar cycloaddition became the most famous example of so-called "<a href="/facts/Click_chemistry/DzX03jLU">click chemistry</a>"<a class="footnote-ref" id="fnref:10" href="#fn:10">10</a><a class="footnote-ref" id="fnref:11" href="#fn:11">11</a> (perhaps, the only one known to a non-specialist), and the field of organic azides exploded.

<h2 id="preparation">Preparation</h2>

Myriad methods exist, most often using preformed azide-containing reagent.

<h3>Alkyl azides</h3>
<h4>By halide displacement</h4>
As a <a href="/facts/Pseudohalide/9DMN43ya">pseudohalide</a>, azide generally displaces many leaving group, e.g. Br−, I−, <a href="/facts/Tosyl_group/Q4qU62D1">Ts</a>O−, <a href="/facts/Sulfonate/ApbgQMXB">sulfonate</a>,<a class="footnote-ref" id="fnref:12" href="#fn:12">12</a><a class="footnote-ref" id="fnref:13" href="#fn:13">13</a> and others to give the azido compound.<a class="footnote-ref" id="fnref:14" href="#fn:14">14</a> The azide source is most often <a href="/facts/Sodium_azide/4gwc2jzu">sodium azide</a> (NaN3), although <a href="/facts/Lithium_azide/4S1YV1VA">lithium azide</a> (LiN3) has been demonstrated.

<h4>From alcohols</h4>
Aliphatic alcohols give azides via a variant of the <a href="/facts/Mitsunobu_reaction/kVuwYbRH">Mitsunobu reaction</a>, with the use of <a href="/facts/Hydrazoic_acid/rbtF5smp">hydrazoic acid</a>.<a class="footnote-ref" id="fnref:15" href="#fn:15">15</a> Hydrazines may also form azides by reaction with <a href="/facts/Sodium_nitrite/t5p4YpvJ">sodium nitrite</a>:<a class="footnote-ref" id="fnref:16" href="#fn:16">16</a> <a href="/facts/Alcohol_(chemistry)/Y0SCTDkh">Alcohols</a> can be converted into azides in one step using 2-azido-1,3-dimethylimidazolinium hexafluorophosphate (ADMP)<a class="footnote-ref" id="fnref:17" href="#fn:17">17</a> or under <a href="/facts/Mitsunobu_reaction/kVuwYbRH">Mitsunobu conditions</a><a class="footnote-ref" id="fnref:18" href="#fn:18">18</a> with <a href="/facts/Diphenylphosphoryl_azide/mS5xjxRe">diphenylphosphoryl azide</a> (DPPA).

<h4>From epoxides and aziridines</h4>
<a href="/facts/Trimethylsilyl_azide/638K9orr">Trimethylsilyl azide</a> (CH3)3SiN3, and <a href="/facts/Tributyltin_azide/IQoctSvR">tributyltin azide</a> (CH3CH2CH2CH2)3SnN3, have all been used,<a class="footnote-ref" id="fnref:19" href="#fn:19">19</a> including <a href="/facts/Enantioselective_synthesis/5hJe37TL">enantioselective</a><a class="footnote-ref" id="fnref:20" href="#fn:20">20</a> modifications of the reaction are also known. Aminoazides are accessible by the epoxide and aziridine ring cleavage, respectively.<a class="footnote-ref" id="fnref:21" href="#fn:21">21</a><a class="footnote-ref" id="fnref:22" href="#fn:22">22</a>

<h4>From amines</h4>
The <a href="/facts/Diazo_transfer/qNcCkYb8">azo transfer</a> compounds, <a href="/facts/Trifluoromethanesulfonyl_azide/XbuK3IWd">trifluoromethanesulfonyl azide</a> and <a href="/facts/Imidazole-1-sulfonyl_azide/7DX5RM0J">imidazole-1-sulfonyl azide</a>, react with amines to give the corresponding azides. Diazo transfer onto amines using <a href="/facts/Trifluoromethanesulfonyl_azide/XbuK3IWd">trifluoromethanesulfonyl azide</a> (<a href="/facts/Trifluoromethylsulfonyl/f4HFjf5K">Tf</a>N3) and <a href="/facts/Tosyl_azide/LbK7oynF">Tosyl azide</a> (<a href="/facts/Tosyl_group/Q4qU62D1">Ts</a>N3) has been reported.<a class="footnote-ref" id="fnref:23" href="#fn:23">23</a>

<h4>Hydroazidation</h4>
Hydroazidation of <a href="/facts/Alkene/RtYcS6kU">alkenes</a> has been demonstrated<a class="footnote-ref" id="fnref:24" href="#fn:24">24</a>

<h3>Aryl azides</h3>
<a href="/facts/Aryl/M3z7QRXd">Aryl</a> azides may be prepared by <a href="/facts/Diazonium_compound/5pkN4G5s">displacement</a> of the appropriate <a href="/facts/Diazonium_salt/5pkN4G5s">diazonium salt</a> with <a href="/facts/Sodium_azide/4gwc2jzu">sodium azide</a> or <a href="/facts/Trimethylsilyl_azide/638K9orr">trimethylsilyl azide</a>. <a href="/facts/Nucleophilic_aromatic_substitution/0TnXnVNz">Nucleophilic aromatic substitution</a> is also possible, even with <a href="/facts/Chlorides/m9NUaUDR">chlorides</a>. <a href="/facts/Aniline/eFXck1Rj">Anilines</a> and <a href="/facts/Aromatic/wK0DzRY6">aromatic</a> <a href="/facts/Hydrazines/3LTsArMQ">hydrazines</a> undergo <a href="/facts/Diazotization/5pkN4G5s">diazotization</a>, as do <a href="/facts/Alkyl/vmEk8X4v">alkyl</a> <a href="/facts/Amines/SN7W44fv">amines</a> and hydrazines.<a class="footnote-ref" id="fnref:25" href="#fn:25">25</a>

<a href="/facts/Phenylhydrazine/a1UlNkeA">PhNHNH2</a> + <a href="/facts/Sodium_nitrite/t5p4YpvJ">NaNO2</a> → <a href="/facts/Phenyl_azide/tczBhkqK">PhN3</a> + NaOH + H2O
<h3>Acyl azides</h3>
Main article: <a href="/facts/Acyl_azide/JLfEvgTW">acyl azide</a>
Alkyl or aryl <a href="/facts/Acyl_chloride/R4ppUXre">acyl chlorides</a> react with <a href="/facts/Sodium_azide/4gwc2jzu">sodium azide</a> in aqueous solution to give <a href="/facts/Acyl_azide/JLfEvgTW">acyl azides</a>,<a class="footnote-ref" id="fnref:26" href="#fn:26">26</a><a class="footnote-ref" id="fnref:27" href="#fn:27">27</a> which give <a href="/facts/Isocyanates/YYDoDBgp">isocyanates</a> in the <a href="/facts/Curtius_rearrangement/ubsp6a7E">Curtius rearrangement</a>.

<h4>Dutt–Wormall reaction</h4>
A classic method for the synthesis of azides is the Dutt–Wormall reaction<a class="footnote-ref" id="fnref:28" href="#fn:28">28</a> in which a <a href="/facts/Diazonium_salt/5pkN4G5s">diazonium salt</a> reacts with a <a href="/facts/Sulfonamide_(chemistry)/h1sVXW41">sulfonamide</a> first to a diazoaminosulfinate and then on <a href="/facts/Hydrolysis/JTvwIHPs">hydrolysis</a> the azide and a <a href="/facts/Sulfinic_acid/Ur6P5qNX">sulfinic acid</a>.<a class="footnote-ref" id="fnref:29" href="#fn:29">29</a>

<h2 id="reactions">Reactions</h2>
Organic azides engage in useful <a href="/facts/Organic_reaction/SESmeGWm">organic reactions</a>. The terminal nitrogen is mildly nucleophilic. Generally, nucleophiles attack the azide at the terminal nitrogen Nγ, while electrophiles react at the internal atom Nα.<a class="footnote-ref" id="fnref:30" href="#fn:30">30</a> Azides easily extrude diatomic <a href="/facts/Nitrogen/Nf1QpGDz">nitrogen</a>, a tendency that is exploited in many reactions such as the Staudinger ligation or the <a href="/facts/Curtius_rearrangement/ubsp6a7E">Curtius rearrangement</a>.<a class="footnote-ref" id="fnref:31" href="#fn:31">31</a>
Azides may be reduced to <a href="/facts/Amine/JvfYJfP6">amines</a> by <a href="/facts/Hydrogenolysis/v8VT0Bx2">hydrogenolysis</a><a class="footnote-ref" id="fnref:32" href="#fn:32">32</a> or with a phosphine (e.g., <a href="/facts/Triphenylphosphine/nYFNCVcJ">triphenylphosphine</a>) in the <a href="/facts/Staudinger_reaction/s63Hyq9D">Staudinger reaction</a>. This reaction allows azides to serve as protected -NH2 synthons, as illustrated by the synthesis of <a href="/facts/1%2c1%2c1-Tris(aminomethyl)ethane/I2zIcSrq">1,1,1-tris(aminomethyl)ethane</a>:

3 H2 + CH3C(CH2N3)3 → CH3C(CH2NH2)3 + 3 N2
In the <a href="/facts/Azide_alkyne_Huisgen_cycloaddition/6qy4czhQ">azide alkyne Huisgen cycloaddition</a>, organic azides react as <a href="/facts/1%2c3-dipole/Sp1NVXl2">1,3-dipoles</a>, reacting with <a href="/facts/Alkyne/VHI4N5Wo">alkynes</a> to give substituted <a href="/facts/1%2c2%2c3-triazole/5TIggyqG">1,2,3-triazoles</a>.
Some azide reactions are shown in the following scheme. Probably the most famous is the reaction with <a href="/facts/Phosphine/aYysn5TS">phosphines</a>, which leads to iminophosphoranes 22; these can be hydrolysed into primary amines 23 (the <a href="/facts/Staudinger_reaction/s63Hyq9D">Staudinger reaction</a>),<a class="footnote-ref" id="fnref:33" href="#fn:33">33</a> react with carbonyl compounds to give imines 24 (the aza-Wittig reaction),<a class="footnote-ref" id="fnref:34" href="#fn:34">34</a><a class="footnote-ref" id="fnref:35" href="#fn:35">35</a><a class="footnote-ref" id="fnref:36" href="#fn:36">36</a> or undergo other transformations. Thermal decomposition of azides gives nitrenes, which participate in a variety of reactions; vinyl azides 19 decompose into 2H-azirines 20.<a class="footnote-ref" id="fnref:37" href="#fn:37">37</a><a class="footnote-ref" id="fnref:38" href="#fn:38">38</a> Alkyl azides with low nitrogen-content ((nC + nO) / nN ≥ 3) are relatively stable and decompose only above ca. 175 °C.<a class="footnote-ref" id="fnref:39" href="#fn:39">39</a>
Direct photochemical decomposition of alkyl azides leads almost exclusively to <a href="/facts/Imine/yK72z07j">imines</a> (e.g. 25 and 26).<a class="footnote-ref" id="fnref:40" href="#fn:40">40</a> It is proposed that the azide group is promoted to the singlet excited state and then undergoes concerted rearrangement without the intermediacy of nitrenes. The presence of triplet sensitisers, however, may change the reaction mechanism and result in the formation of triplet nitrenes. The latter were observed directly by <a href="/facts/ESR_spectroscopy/TDHV8c9e">ESR spectroscopy</a> at −269 °C as well as inferred in some photolyses.<a class="footnote-ref" id="fnref:41" href="#fn:41">41</a><a class="footnote-ref" id="fnref:42" href="#fn:42">42</a> Triplet methyl nitrene is 31 kJ/mol more stable than its singlet form, and thus is most likely the ground state.<a class="footnote-ref" id="fnref:43" href="#fn:43">43</a><a class="footnote-ref" id="fnref:44" href="#fn:44">44</a>
The (3+2)-cycloaddition of azides to double or triple bonds is one of the most utilised <a href="/facts/Cycloaddition/Gme6TDFP">cycloadditions</a> in organic chemistry and affords triazolines (e.g. 17) or <a href="/facts/Triazole/nyYdyRW4">triazoles</a>, respectively.<a class="footnote-ref" id="fnref:45" href="#fn:45">45</a><a class="footnote-ref" id="fnref:46" href="#fn:46">46</a><a class="footnote-ref" id="fnref:47" href="#fn:47">47</a> The uncatalysed reaction is a concerted <a href="/facts/Pericyclic_process/UQ3nKSSD">pericyclic process</a>, in which the configuration of the alkene component is transferred to the triazoline product. The Woodward–Hoffmann denomination is [π4s+π2s] and the reaction is symmetry-allowed. According to Sustmann, this is a Type II cycloaddition, which means the two <a href="/facts/HOMO_and_LUMO/XyofpH0p">HOMOs</a> and the two <a href="/facts/HOMO_and_LUMO/XyofpH0p">LUMOs</a> have comparable energies, and thus both electron-withdrawing and electron-donating substituents may lead to an increase in the reaction rate.<a class="footnote-ref" id="fnref:48" href="#fn:48">48</a><a class="footnote-ref" id="fnref:49" href="#fn:49">49</a> The reaction is generally free from significant solvent effects because both the reactants and the <a href="/facts/Transition_state/34PsdqRd">transition state</a> (TS) are non-polar.<a class="footnote-ref" id="fnref:50" href="#fn:50">50</a>
Another azide regular is <a href="/facts/Tosyl_azide/LbK7oynF">tosyl azide</a> here in reaction with <a href="/facts/Norbornadiene/FHj3Pnwr">norbornadiene</a> in a nitrogen insertion reaction:<a class="footnote-ref" id="fnref:51" href="#fn:51">51</a>

<h2 id="applications">Applications</h2>
Some azides are valuable as <a href="/facts/Bioorthogonal_chemical_reporters/yDK48RJq">bioorthogonal chemical reporters</a>, molecules that can be "clicked" to see the metabolic path it has taken inside a living system.
The antiviral drug <a href="/facts/Zidovudine/8fBluxK3">zidovudine</a> (AZT) contains an azido group.

This article incorporates <a href="https://ora.ox.ac.uk/objects/uuid:d7e4bbea-4009-4e7e-838c-46b4bb81bc13">text</a> by Oleksandr Zhurakovskyi available under the CC BY 2.5 license.

<h2 id="additional-sources">Additional sources</h2>
<ul><li>Patai, Saul, ed. (1971-01-01). <a href="http://doi.wiley.com/10.1002/9780470771266">The Azido Group (1971)</a>. PATai's Chemistry of Functional Groups. Chichester, UK: John Wiley & Sons, Ltd. p. 626. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1002%2F9780470771266">10.1002/9780470771266</a>. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-470-77126-6.</li>
<li>Scriven, Eric F. Azides and Nitrenes: Reactivity and Utility. Academic Press. p. 542. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 9780124143074.</li>
<li>Padwa, Albert; Pearson, William H., eds. (2002-04-05). <a href="http://doi.wiley.com/10.1002/0471221902">Synthetic Applications of 1,3-Dipolar Cycloaddition Chemistry Toward Heterocycles and Natural Products: Padwa/Dipolar Cycloaddition E-Bk</a>. Chemistry of Heterocyclic Compounds: A Series Of Monographs. Vol. 59. New York, USA: John Wiley & Sons, Inc. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1002%2F0471221902">10.1002/0471221902</a>. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-471-38726-8.</li>
<li>Wolff, H. Org. React. 1946, 3, 337–349.</li>
<li>Boyer, J. H.; Canter, F. C. (1954-02-01). <a href="https://pubs.acs.org/doi/abs/10.1021/cr60167a001">"Alkyl and Aryl Azides"</a>. Chemical Reviews. 54 (1): 1–57. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1021%2Fcr60167a001">10.1021/cr60167a001</a>. <a href="/facts/ISSN_(identifier)/DPAflDvU">ISSN</a> <a href="https://search.worldcat.org/issn/0009-2665">0009-2665</a>.</li>
<li>Scriven, Eric F. V.; Turnbull, Kenneth (March 1988). <a href="https://pubs.acs.org/doi/abs/10.1021/cr00084a001">"Azides: Their Preparation and synthetic uses"</a>. Chemical Reviews. 88 (2): 297–368. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1021%2Fcr00084a001">10.1021/cr00084a001</a>. <a href="/facts/ISSN_(identifier)/DPAflDvU">ISSN</a> <a href="https://search.worldcat.org/issn/0009-2665">0009-2665</a>.</li>
<li>Bräse, Stefan; Gil, Carmen; Knepper, Kerstin; Zimmermann, Viktor (2005-08-19). <a href="https://onlinelibrary.wiley.com/doi/10.1002/anie.200400657">"Organic Azides: An Exploding Diversity of a Unique Class of Compounds"</a>. Angewandte Chemie International Edition. 44 (33): 5188–5240. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1002%2Fanie.200400657">10.1002/anie.200400657</a>. <a href="/facts/ISSN_(identifier)/DPAflDvU">ISSN</a> <a href="https://search.worldcat.org/issn/1433-7851">1433-7851</a>. <a href="/facts/PMID_(identifier)/JlHAvMHt">PMID</a> <a href="https://pubmed.ncbi.nlm.nih.gov/16100733">16100733</a>.</li>
<li>Schmidt, Eckart W. (2022). "Organic Azido Compounds". Azides and Azido Compounds. Encyclopedia of Liquid Fuels. De Gruyter. pp. 901–952. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1515%2F9783110750287-011">10.1515/9783110750287-011</a>. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-3-11-075028-7.</li></ul>
<h2 id="external-links">External links</h2>

Look up azide or azido- in Wiktionary, the free dictionary.

Wikimedia Commons has media related to Organoazides.

<ul><li><a href="https://www.organic-chemistry.org/synthesis/C1N/azides/index.shtm">Synthesis of organic azides</a>, recent methods</li>
<li><a href="http://www.ehs.ucsb.edu/units/labsfty/labrsc/factsheets/Azides_FS26.pdf">Synthesizing, Purifying, and Handling Organic Azides</a></li></ul>

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

<ol>
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<li id="fn:6">Huisgen, R. (November 1963). "Kinetics and Mechanism of 1,3-Dipolr Cycloadditions". Angewandte Chemie International Edition in English. 2 (11): 633–645. doi:10.1002/anie.196306331. ISSN 0570-0833. <a href="https://onlinelibrary.wiley.com/doi/10.1002/anie.196306331" target="_blank">https://onlinelibrary.wiley.com/doi/10.1002/anie.196306331</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">Organic azides: syntheses and applications. Stefan Bräse, Klaus Banert. Chichester, West Sussex, U.K.: John Wiley. 2010. ISBN 978-0-470-68252-4. OCLC 587390490.{{cite book}}: CS1 maint: others (link) <a href="978-0-470-68252-4" target="_blank">978-0-470-68252-4</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
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</ol>

Organic azide open-in-new

Organic azide