Aziridine is an organic compound consisting of the three-membered heterocycle .[ Epoxides and aziridines – A mini review Albert Padwa, S. Shaun Murphree Arkivoc (JC-1522R) pp. 6–33 Online article] It is a colorless, toxic, volatile liquid that is of significant practical interest.
Structure
The
in aziridine are approximately 60°, considerably less than the normal
hydrocarbon bond angle of 109.5°, which results in
Ring 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 isomer and
trans isomer invertomers of
N-chloro-2-methylaziridine.
Synthesis and uses
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 (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 alkylation, it is also a mutagen.[ It is reactive toward DNA, potentially relevant to its mutagenicity. Aziridine containing compounds also appear to be similarly dangerous.]
See also
-
Binary ethylenimine, a dimeric form of aziridine
