:Aziridine
{{Short description|Organic ring compound with the formula (CH2)2NH}}
{{Chembox
| Watchedfields = changed
| verifiedrevid = 443409998
| ImageFileL1 = Aziridine.svg
| ImageFileR1 = Aziridine3d.png
| PIN = Aziridine
| SystematicName = Azacyclopropane
| OtherNames = Azirane
Ethylenimine
Aminoethylene
Dimethyleneimine
Dimethylenimine
Ethylimine
| Section1 = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 8682
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C11687
| InChI = 1/C2H5N/c1-2-3-1/h3H,1-2H2
| InChIKey = NOWKCMXCCJGMRR-UHFFFAOYAE
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 540990
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C2H5N/c1-2-3-1/h3H,1-2H2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = NOWKCMXCCJGMRR-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 151-56-4
| EINECS = 205-793-9
| PubChem = 9033
| RTECS = KX5075000
| UNNumber = 1185
| UNII = 54P5FEX9FH
| Beilstein = 102380
| Gmelin = 616
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 30969
| SMILES = C1CN1
}}
| Section2 = {{Chembox Properties
| C=2 | H=5 | N=1
| MeltingPtC = −77.9
| BoilingPtC = 56
| Solubility = miscible
| VaporPressure = 160 mmHg (20°C)
}}
| Section3 = {{Chembox Hazards
| MainHazards = highly flammable and toxic
| NFPA-H = 4
| NFPA-F = 3
| NFPA-R = 3
| GHSPictograms = {{GHS02}}{{GHS05}}{{GHS06}}{{GHS08}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|225|300|310|314|330|340|350|411}}
| PPhrases = {{P-phrases|201|202|210|233|240|241|242|243|260|262|264|270|271|273|280|281|284|301+310|301+330+331|302+350|303+361+353|304+340|305+351+338|308+313|310|320|321|322|330|361|363|370+378|391|403+233|403+235|405|501}}
| FlashPtC = -11
| AutoignitionPtC = 322
| ExploLimits = 3.6–46%
| IDLH = Ca [100 ppm]{{PGCH|0274}}
| PEL = OSHA-Regulated Carcinogen
| LCLo = 25 ppm (guinea pig, 8 hr)
56 ppm (rabbit, 2 hr){{IDLH|151564|Ethyleneimine}}
| LC50 = 250 ppm (rat, 1 hr)
250 ppm (guinea pig, 1 hr)
62 ppm (rat, 4 hr)
223 ppm (mouse, 2 hr)
56 ppm (rat, 2 hr)
2236 ppm (mouse, 10 min)
}}
| Section8 = {{Chembox Related
| OtherFunction = Borirane
Ethylene oxide
Thiirane
| OtherFunction_label = heterocycles
| OtherCompounds =
}}
}}
{{for|the general class|Aziridines}}
Aziridine is an organic compound consisting of the three-membered heterocycle {{chem2|C2H5N}}.{{cite book |author=Gilchrist, T.L. |title=Heterocyclic chemistry |year=1987 |publisher=Longman Scientific & Technical |isbn=978-0-582-01421-3 }}Epoxides and aziridines – A mini review Albert Padwa, S. Shaun Murphree Arkivoc (JC-1522R) pp. 6–33 [http://www.arkat-usa.org/ark/journal/2006/I03_Coxon/1522/JC-1522R.asp Online article] It is a colorless, toxic, volatile liquid that is of significant practical interest.{{Ullmann|doi=10.1002/14356007.a03_239.pub2|title=Aziridines|year=2006|last1=Steuerle|first1=Ulrich|last2=Feuerhake|first2=Robert|isbn=3527306730}} Aziridine was discovered in 1888 by the chemist Siegmund Gabriel.{{Cite journal|last=Gabriel|first=S.|date=1888|title=Ueber Vinylamin und Bromäthylamin. (II.)|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/cber.18880210287|journal=Berichte der Deutschen Chemischen Gesellschaft|language=en|volume=21|issue=2|pages=2664–2669|doi=10.1002/cber.18880210287|issn=1099-0682|url-access=subscription}} Its derivatives, also referred to as aziridines, are of broader interest in medicinal chemistry.
Structure
The bond angles in aziridine are approximately 60°, considerably less than the normal hydrocarbon bond angle of 109.5°, which results in angle strain as in the comparable cyclopropane and ethylene oxide molecules. A banana bond model explains bonding in such compounds. Aziridine is less basic than acyclic aliphatic amines, with a pKa of 7.9 for the conjugate acid, due to increased s character of the nitrogen free electron pair. Angle strain in aziridine also increases the barrier to nitrogen inversion. This barrier height permits the isolation of separate invertomers, for example the cis and trans invertomers of N-chloro-2-methylaziridine.
Synthesis and uses
{{multiple image
| align = left
| direction = vertical
| width = 230
| image1 = Linear PEI.png
| caption1 = Linear polyethylenimine (PEI) fragment, derived from aziridine.
| image2 = Branched PEI.png
| caption2 = Typical branched PEI fragment, derived from aziridine.
| background color = #FFFFFF
}}
Aziridine is produced industrially from aminoethanol via two related routes. The Nippon Shokubai process requires an oxide catalyst and high temperatures to effect the dehydration. In the Wenker synthesis, the aminoethanol is converted to the sulfate ester, which undergoes base-induced sulfate elimination. Older methods entailed amination of 1,2-dichloroethane and cyclization of 2-chloroethylamine.
Aziridine forms a wide variety of polymeric derivatives, known as polyethylenimines (PEI). These and related species are useful crosslinking agents and precursors for coatings.
Safety
Aziridine is highly toxic with an LD50 of 14 mg (oral, rats). It is a skin irritant. As an alkylating agent, it is also a mutagen. It is reactive toward DNA, potentially relevant to its mutagenicity. Aziridine containing compounds also appear to be similarly dangerous.{{cite journal |vauthors=Kanerva L, Keskinen H, Autio P, Estlander T, Tuppurainen M, Jolanki R |title=Occupational respiratory and skin sensitization caused by polyfunctional aziridine hardener |journal=Clin Exp Allergy |volume=25 |issue=5 |pages=432–9 |date=May 1995 |pmid=7553246 |doi=10.1111/j.1365-2222.1995.tb01074.x |s2cid=28101810 }}{{cite journal |vauthors=Sartorelli P, Pistolesi P, Cioni F, Napoli R, Sisinni AG, Bellussi L, Passali GC, Cherubini Di Simplicio E, Flori L |title=Skin and respiratory allergic disease caused by polyfunctional aziridine |journal=Med Lav |volume=94 |issue=3 |pages=285–95 |year=2003 |pmid=12918320 }}{{cite journal |author=Mapp CE |title=Agents, old and new, causing occupational asthma |journal=Occup. Environ. Med. |volume=58 |pages=354–60 |year=2001 |pmid=11303086 |doi=10.1136/oem.58.5.354 |issue=5 |pmc=1740131 }}
See also
- Binary ethylenimine, a dimeric form of aziridine