Diimide: Difference between revisions

{{distinguish|carbodiimide}}{{Redirect-distinguish|Diazene|diazine|diazane}}{{See also|Azo compound}}

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 443793481

| ImageFileL1 = Trans-diazene-2D.png

| ImageFileL1_Ref = {{Chemboximage|correct|??}}

| ImageNameL1 = Ball and stick model of diazene ((E)-diazene)

| ImageCaptionL1 = ''E''/''trans''-diazene

| ImageFileR1 = Trans-diazene-3D-balls.png

| ImageFileR1_Ref = {{Chemboximage|correct|??}}

| ImageNameR1 = Structural formula of diazene ((E)-diazene)

| ImageFileL2 = Cis-diazene-2D.png

| ImageFileL2_Ref = {{Chemboximage|correct|??}}

| ImageNameL2 = Structural formula of diazene ((Z)-diazene)

| ImageCaptionL2 = ''Z''/''cis''-diazene

| ImageFileR2 = Cis-diazene-3D-balls.png

| ImageFileR2_Ref = {{Chemboximage|correct|??}}

| ImageNameR2 = Ball and stick model of diazene ((Z)-diazene)

| IUPACName = Diazene

| OtherNames = Diimide<br/>Diimine<br />Dihydridodinitrogen<br />Azodihydrogen

| Section1 = {{Chembox Identifiers

| CASNo = 3618-05-1

| CASNo_Ref = {{cascite|correct|??}}

| CASNo1 = 15626-43-4

| CASNo1_Ref = {{cascite|correct|??}}

| CASNo1_Comment = (''E'')-diazene

| CASNo2 = 15626-42-3

| CASNo2_Ref = {{cascite|correct|??}}

| CASNo2_Comment = (''Z'')-diazene

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = LM321PYV3Y

| PubChem = 123195

| ChemSpiderID = 10612167

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| KEGG_Ref = {{keggcite|correct|kegg}}

| MeSHName = Diazene

| ChEBI_Ref = {{ebicite|correct|EBI}}

| SMILES = N=N

| StdInChI = 1S/H2N2/c1-2/h1-2H

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| InChI = 1/H2N2/c1-2/h1-2H

| StdInChIKey = RAABOESOVLLHRU-UHFFFAOYSA-N

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| InChIKey = RAABOESOVLLHRU-UHFFFAOYAG}}

| Section2 = {{Chembox Properties

| Formula =

| H=2 | N=2

| Appearance = Yellow gas

| MeltingPtC = -80

}}

| Section9 = {{Chembox Related

| OtherAnions = [[diphosphene]]<br>[[dinitrogen difluoride]]

| OtherCations = [[azo compound]]s

| OtherFunction_label = Binary [[azane]]s

| OtherFunction = {{ubl|[[ammonia]]|[[hydrazine|diazane]]|[[triazane]]}}

| OtherCompounds = {{ubl|[[isodiazene]]|[[triazene]]|[[tetrazene]]}}

}}

}}

'''Diimide''', also called '''diazene''' or '''diimine''', is a compound having the formula HN=NH. It exists as two [[geometric isomer]]s, ''E'' (''trans'') and ''Z'' (''cis''). The term diazene is more common for organic derivatives of diimide. Thus, [[azobenzene]] is an example of an organic diazene.

A traditional route to diimide involves oxidation of [[hydrazine]] with hydrogen peroxide or air.<ref name=OS>{{OrgSynth | author1 = Ohno, M.|author2=Okamoto, M. | title = cis-Cyclododecene | collvol = 5 | collvolpages = 281 | year = 1973 | prep = cv5p0281}}</ref>

:{{chem2|N2H4 + H2O2 -> N2H2 + 2H2O}}

Alternatively the hydrolysis of [[diethyl azodicarboxylate]] or [[azodicarbonamide]] affords diimide:<ref>{{cite book | title = Inorganic Chemistry |author1=Wiberg, E. |author2=Holleman, A. F. | publisher = [[Elsevier]] | year = 2001 | isbn = 9780123526519 | chapter = 1.2.7: Diimine, N₂H₂ | page = 628 | chapter-url = https://books.google.com/books?id=LxhQPdMRfVIC&pg=PA628}}</ref>

:{{chem2|Et\sO2C\sN\dN\sCO2\sEt → HN\dNH + 2 CO2 + 2 HOEt}}

Nowadays, diimide is generated by thermal decomposition of 2,4,6‐triisopropylbenzenesulfonylhydrazide.<ref>{{cite book |doi=10.1002/047084289X.rt259.pub2|chapter=2,4,6-Triisopropylbenzenesulfonylhydrazide|title=Encyclopedia of Reagents for Organic Synthesis|year=2008|last1=Chamberlin|first1=A. Richard|last2=Sheppeck|first2=James E.|last3=Somoza|first3=Alvaro|isbn=978-0471936237}}</ref>

Because of its instability, diimide is generated and used ''in-situ''. A mixture of both the ''cis'' (''Z-'') and ''trans'' (''E-'') isomers is produced. Both isomers are unstable, and they undergo a slow interconversion. The ''trans'' isomer is more stable, but the ''cis'' isomer is the one that reacts with unsaturated substrates, therefore the equilibrium between them shifts towards the ''cis'' isomer due to [[Le Chatelier's principle]]. Some procedures call for the addition of carboxylic acids, which catalyse the cis–trans isomerization.<ref name=Pasto/> Diimide decomposes readily. Even at low temperatures, the more stable ''trans'' isomer rapidly undergoes various disproportionation reactions, primarily forming [[hydrazine]] and [[nitrogen gas]]:<ref>{{cite book |title= Inorganic Chemistry |year= 2001 | publisher= Academic Press |isbn= 978-0123526519 | editor1-first= Nils |editor1-last= Wiberg |editor2-first= A. F. |editor2-last= Holleman |editor3-first= Egon |editor3-last= Wiberg |section= 1.2.7 Diimine N₂H₂ [1.13.17] |pages= 628–632}}</ref>

:{{chem2|2 HN\dNH → H2N\sNH2 + N2}}

Diimide is occasionally useful as a reagent in [[organic synthesis]].<ref name=Pasto>{{ cite encyclopedia | first = D. J. | last = Pasto | title = Diimide | encyclopedia = Encyclopedia of Reagents for Organic Synthesis | year = 2001 | publisher = John Wiley & Sons | doi = 10.1002/047084289X.rd235 | isbn = 0471936235 }}</ref> It hydrogenates alkenes and alkynes with selective delivery of hydrogen from one face of the substrate resulting in the same stereoselectivity as metal-catalysed ''syn'' addition of {{chem2|H2}}. The only coproduct released is nitrogen gas. Although the method is cumbersome, the use of diimide avoids the need for high pressures or hydrogen gas and metal catalysts, which can be expensive.<ref>{{ cite journal | author = Miller, C. E. | title = Hydrogenation with Diimide | journal = Journal of Chemical Education | year = 1965 | volume = 42 | issue = 5 | pages = 254–259 | doi = 10.1021/ed042p254 | bibcode = 1965JChEd..42..254M }}</ref> The hydrogenation mechanism involves a six-membered {{chem2|C2H2N2}} transition state:

:[[File:DiimineReduction.png|500px|Mechanism of hydrogenation using diimide.]]

Diimide is advantageous because it selectively reduces alkenes and alkynes and is unreactive toward many [[functional group]]s that would interfere with normal [[catalytic hydrogenation]]. Thus, [[peroxide]]s, [[alkyl halide]]s, and [[thiol]]s are tolerated by diimide, but these same groups would typically be degraded by metal catalysts. The reagent preferentially reduces alkynes and unhindered or strained alkenes<ref name=OS/> to the corresponding alkenes and alkanes.<ref name=Pasto/>

==Related==

The [[dication]]ic form, {{chem2|H\sN+\tN+\sH}} (diazynediium, diprotonated dinitrogen), is calculated to have the strongest known chemical bond. This ion can be thought of as a doubly protonated nitrogen molecule. The [[relative bond strength order]] (RBSO) is 3.38.<ref name=kal13>{{cite journal|last1=Kalescky|first1=Robert|last2=Kraka|first2=Elfi|last3=Cremer|first3=Dieter|title=Identification of the Strongest Bonds in Chemistry|journal=The Journal of Physical Chemistry A|date=12 September 2013|volume=117|issue=36|pages=8981–8995|doi=10.1021/jp406200w|pmid=23927609|bibcode=2013JPCA..117.8981K|s2cid=11884042 }}</ref> [[Dinitrogen monofluoride|{{chem2|F\sN+\tN+\sH}}]] (fluorodiazynediium ion) and [[Dinitrogen difluoride|{{chem2|F\sN+\tN+\sF}}]] (difluorodiazynediium ion) have slightly lower strength bonds.<ref name=kal13/>

In the presence of strong bases, diimide deprotonates to form the [[pernitride]] anion, {{chem2|N-\dN-}}.

{{Hydrides by group}}

[[Category:Reducing agents]]

[[Category:Gases with color]]