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Preferred IUPAC name
Systematic IUPAC name
Other names
Ethylene imine
3D model (JSmol)
ECHA InfoCard 100.005.268 Edit this at Wikidata
EC Number
  • 205-793-9
RTECS number
  • KX5075000
UN number 1185
  • InChI=1S/C2H5N/c1-2-3-1/h3H,1-2H2 checkY
  • InChI=1/C2H5N/c1-2-3-1/h3H,1-2H2
  • C1CN1
Molar mass 43.069 g·mol−1
Appearance Colorless oily liquid[1]
Odor ammonia-like[2]
Density 0.8321 g/mL 20 °C[3]
Melting point −77.9 °C (−108.2 °F; 195.2 K)
Boiling point 56 °C (133 °F; 329 K)
Vapor pressure 160 mmHg (20° C)[2]
Occupational safety and health (OHS/OSH):
Main hazards
highly flammable and toxic
GHS labelling:
GHS02: FlammableGHS05: CorrosiveGHS06: ToxicGHS08: Health hazardGHS09: Environmental hazard
H225, H300, H310, H314, H330, H340, H350, H411
P201, P202, P210, P233, P240, P241, P242, P243, P260, P262, P264, P270, P271, P273, P280, P281, P284, P301+P310, P301+P330+P331, P302+P350, P303+P361+P353, P304+P340, P305+P351+P338, P308+P313, P310, P320, P321, P322, P330, P361, P363, P370+P378, P391, P403+P233, P403+P235, P405, P501
NFPA 704 (fire diamond)
Flash point −11 °C (12 °F; 262 K)
322 °C (612 °F; 595 K)
Explosive limits 3.6–46%
Lethal dose or concentration (LD, LC):
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)[4]
25 ppm (guinea pig, 8 hr)
56 ppm (rabbit, 2 hr)[4]
NIOSH (US health exposure limits):
PEL (Permissible)
OSHA-Regulated Carcinogen[2]
REL (Recommended)
IDLH (Immediate danger)
Ca [100 ppm][2]
Related compounds
Related heterocycles
Ethylene oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Aziridine is an organic compound consisting of the three-membered heterocycle (CH2)2NH.[5][6] It is a colorless, toxic, volatile liquid that is of significant practical interest.[7] Aziridine was discovered in 1888 by the chemist Siegmund Gabriel.[8] Its derivatives, also referred to as aziridines, are of broader interest in medicinal chemistry.


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

Linear polyethylenimine (PEI) fragment, derived from aziridine.
Typical branched PEI fragment, derived from aziridine.

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.[7]

Aziridine forms a wide variety of polymeric derivatives, known as polyethylenimines (PEI). These and related species are useful crosslinking agents and precursors for coatings.[7]


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.[7] It is reactive toward DNA, potentially relevant to its mutagenicity. Aziridine containing compounds also appear to be similarly dangerous.[9][10][11]

See also


  1. ^ "Aziridine" (PDF). Re-evaluation of Some Organic Chemicals, Hydrazine and Hydrogen Peroxide. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Vol. 71. 1999.
  2. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0274". National Institute for Occupational Safety and Health (NIOSH).
  3. ^ Weast, Robert C.; et al. (1978). CRC Handbook of Chemistry and Physics (59th ed.). West Palm Beach, FL: CRC Press. ISBN 0-8493-0549-7.
  4. ^ a b "Ethyleneimine". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  5. ^ Gilchrist, T.L. (1987). Heterocyclic chemistry. ISBN 978-0-582-01421-3.
  6. ^ Epoxides and aziridines – A mini review Albert Padwa, S. Shaun Murphree Arkivoc (JC-1522R) pp. 6–33 Online article
  7. ^ a b c d Steuerle, Ulrich; Feuerhake, Robert (2006). "Aziridines". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_239.pub2.
  8. ^ Gabriel, S. (1888). "Ueber Vinylamin und Bromäthylamin. (II.)". Berichte der deutschen chemischen Gesellschaft. 21 (2): 2664–2669. doi:10.1002/cber.18880210287. ISSN 1099-0682.
  9. ^ Kanerva L, Keskinen H, Autio P, Estlander T, Tuppurainen M, Jolanki R (May 1995). "Occupational respiratory and skin sensitization caused by polyfunctional aziridine hardener". Clin Exp Allergy. 25 (5): 432–9. doi:10.1111/j.1365-2222.1995.tb01074.x. PMID 7553246. S2CID 28101810.
  10. ^ Sartorelli P, Pistolesi P, Cioni F, Napoli R, Sisinni AG, Bellussi L, Passali GC, Cherubini Di Simplicio E, Flori L (2003). "Skin and respiratory allergic disease caused by polyfunctional aziridine". Med Lav. 94 (3): 285–95. PMID 12918320.
  11. ^ Mapp CE (2001). "Agents, old and new, causing occupational asthma". Occup. Environ. Med. 58 (5): 354–60. doi:10.1136/oem.58.5.354. PMC 1740131. PMID 11303086.