Aziridine

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] Its derivatives, also referred to as aziridines, are of broader interest in medicinal chemistry.

Aziridine
Names
Preferred IUPAC name
Aziridine
Systematic IUPAC name
Azacyclopropane
Other names
Azirane
Ethylene imine
Aminoethylene
Dimethyleneimine
Dimethylenimine
Ethylimine
Identifiers
3D model (JSmol)
102380
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.005.268
EC Number
  • 205-793-9
616
KEGG
RTECS number
  • KX5075000
UNII
UN number 1185
Properties
C2H5N
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)
miscible
Vapor pressure 160 mmHg (20° C)[2]
Hazards
Main hazards highly flammable and toxic
GHS pictograms
GHS Signal word Danger
H225, H300, H310, H314, H318, H330, H340, H350, H411
P201, P202, P210, P233, P240, P241, P242, P243, P260, P262, P264, P270, P271, P273, P280, P281, P284, P301+310, P301+330+331, P302+350, P303+361+353, P304+340, P305+351+338, P308+313, P310
NFPA 704 (fire diamond)
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineHealth code 4: Very short exposure could cause death or major residual injury. E.g. VX gasReactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
3
4
3
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)
 Ca[2]
IDLH (Immediate danger)
 Ca [100 ppm][2]
Related compounds
Related heterocycles
 Borirane
Ethylene oxide
Thiirane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references
For the general class, see Aziridines.

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
Linear 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. These and related species are useful crosslinking agents and precursors for coatings.[7]

Safety

Aziridine is highly toxic with an LD50 of 14 mg (oral, rats). It is a skin irritant. As an alkylating agent, it also a mutagen.[7] It is subject to attack and ring-opening by endogenous nucleophiles such as nitrogenous bases in DNA base pairs, resulting in potential mutagenicity.[8][9][10]

See also

References
  1. "Aziridine" (PDF). Re-evaluation of Some Organic Chemicals, Hydrazine and Hydrogen Peroxide. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. 71. 1999.
  2. 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. "Ethyleneimine". Immediately Dangerous to Life and 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. Steuerle, Ulrich; Feuerhake, Robert (2006). "Aziridines". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_239.pub2.
  8. 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.
  9. 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.
  10. 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.
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