iodine azide
{{Distinguish|text=Nitrogen triiodide (NI3)}}
{{Chembox
| Name = Iodine azide
| ImageFile = Iodazid.svg
| OtherNames = Azidoiodine, Iodo azide
| IUPACName = Iodine azide
| SystematicName =
| Section1 = {{Chembox Identifiers
| CASNo = 14696-82-3
| PubChem = 61763
| ChemSpiderID = 55652
| InChI = InChI=1S/IN3/c1-3-4-2
| SMILES = IN=[N+]=[N-]
}}
| Section2 = {{Chembox Properties
| Appearance = yellow solid
| Formula = {{chem2|IN3}}
| MolarMass = 168.92 g/mol
| VaporPressure = 2 Torr
| Solubility = decomposes
}}
| Section3 = {{Chembox Structure
| CrystalStruct = orthorhombic
| SpaceGroup = Pbam, No. 55
}}
| Section9 = {{Chembox Related
| OtherCompounds = Hydrazoic acid
Fluorine azide
Chlorine azide
Bromine azide
}}
}}
Iodine azide ({{chem2|IN3}}) is an explosive inorganic compound, which in ordinary conditions is a yellow solid.{{Cite journal|last1=Buzek|first1=Peter|last2=Klapötke|first2=Thomas M.|last3=von Ragué Schleyer|first3=Paul|last4=Tornieporth-Oetting|first4=Inis C.|last5=White|first5=Peter S.|date=1993|title=Iodine Azide|url=https://onlinelibrary.wiley.com/doi/epdf/10.1002/anie.199302751|journal=Angewandte Chemie International Edition|volume=32|issue=2|pages=275–277|doi=10.1002/anie.199302751}} Formally, it is an inter-pseudohalogen.
Preparation
Iodine azide can be prepared from the reaction between silver azide and elemental iodine:
:{{chem2|AgN3 + I2 → IN3 + AgI}}
Since silver azide can only be handled safely while moist, but even small traces of water cause the iodine azide to decompose, this synthesis is done by suspending the silver azide in dichloromethane and adding a drying agent before reaction with the iodine. In this way, a pure solution of iodine azide results, which can then be carefully evaporated to form needle-shaped golden crystals.{{Cite journal|last=Dehnicke|first=Kurt|date=1979|title=The Chemistry of Iodine Azide|url=https://onlinelibrary.wiley.com/doi/epdf/10.1002/anie.197905071|journal=Angewandte Chemie International Edition|volume=18|issue=7|pages=507–514|doi=10.1002/anie.197905071}}
This reaction was used in the original synthesis of iodine azide in 1900, where it was obtained as unstable solutions in ether and impure crystals contaminated by iodine.{{Cite journal|last=Hantzsch|first=Arthur|date=1900|title=Ueber den Jodstickstoff N3|url=https://chemistry-europe.onlinelibrary.wiley.com/doi/epdf/10.1002/cber.19000330182|journal=Berichte der Deutschen Chemischen Gesellschaft|volume=33|issue=1|pages=522–527|doi=10.1002/cber.19000330182}}
Iodine azide can also be generated in situ by reacting iodine monochloride and sodium azide under conditions where it is not explosive.{{Cite journal|last1=Marinescu|first1=Lavinia|last2=Thinggaard|first2=Jacob|last3=Thomsen|first3=Ib B.|last4=Bols|first4=Mikael|date=2003|title=Radical Azidonation of Aldehydes|url=https://pubs.acs.org/doi/10.1021/jo035163v|journal=Journal of Organic Chemistry|volume=68|issue=24|pages=9453–9455|doi=10.1021/jo035163v|pmid=14629171 }}
Properties
In the solid state, iodine azide exists as a one-dimensional polymeric structure,{{Cite journal|last1=Lyhs|first1=Benjamin|last2=Bläser|first2=Dieter|last3=Wölper|first3=Christoph|last4=Schulz|first4=Stephan|last5=Jansen|first5=Georg|date=2012|title=A Comparison of the Solid-State Structures of Halogen Azides XN3 (X=Cl, Br, I)|url=https://onlinelibrary.wiley.com/doi/epdf/10.1002/anie.201206028|journal=Angewandte Chemie International Edition|volume=51|issue=51|pages=12859–12863|doi=10.1002/anie.201206028|pmid=23143850 }} forming two polymorphs, both of which crystallize in an orthorhombic lattice with the space group Pbam. The gas phase exists as monomeric units.{{cite book|last1=Hassner|first1=Alfred|last2=Marinescu|first2=Lavinia|last3=Bols|first3=Mikael|chapter=Iodine Azide|title=Encyclopedia of Reagents for Organic Synthesis|year=2005 |url=https://onlinelibrary.wiley.com/doi/full/10.1002/047084289X.ri007.pub2|doi=10.1002/047084289X.ri007|isbn=0471936235 }}
Iodine azide exhibits both high reactivity and comparative stability, consequences of the polarity of the I–N bond. The {{chem2|N3}} group introduced by substitution with iodine azide can frequently undergo subsequent reactions due to its high energy content.
The isolated compound is strongly shock- and friction-sensitive.{{Cite book|last=Urben|first=P. G.|title=Bretherick's Handbook of Reactive Chemical Hazards|publisher=Butterworth-Heinemann|year=1999|isbn=0-7506-3605-X|edition=6th|volume=1}} Its explosivity has been characterized as follows:
| class="wikitable"
|Normal gas volume |265 L/kg |
| Heat of explosion
|2091 kJ/kg |
| Trauzl rating
|14.0 cm3/g |
These values lie significantly lower in comparison to classical explosives like TNT or RDX, and also to acetone peroxide. Dilute solutions (< 3%) of the compound in dichloromethane can be handled safely.
Uses
Despite its explosive character, iodine azide has many practical uses in chemical synthesis. Similar to bromine azide, it can add across an alkene double bond via both ionic and radical mechanisms, giving anti stereoselectivity. Addition of {{chem2|IN3}} to an alkene followed by reduction with lithium aluminium hydride is a convenient method of aziridine synthesis. Azirines can also be synthesized from the addition product by adding base to eliminate HI, giving a vinyl azide {{chem2|CH2\dCHN3}} which undergoes thermolysis to form an azirine. Further radical modes of reactivity include radical substitutions on weak C-H bonds to form α‐azido ethers, benzal acetals, and aldehydes, and the conversion of aldehydes to acyl azides.
External links
- [http://www.irdg.org/the-infrared-and-raman-discussion-group/ijvs/ijvs-volume-3-edition-6/the-raman-spectrum-of-iodine-azide-in3/ Raman spectrum of iodine azide]
References
{{Azides}}
{{Nitrogen compounds}}