Aziridine is an
organic compound consisting of the three-membered
heterocycle . It is a colorless, toxic, volatile liquid that is of significant practical interest.
Aziridine was discovered in 1888 by the chemist
Siegmund Gabriel. 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
Cyclopropane is the cycloalkane with the molecular formula (CH2)3, consisting of three methylene groups (CH2) linked to each other to form a ring. The small size of the ring creates substantial ring strain in the structure. Cyclopropane itself ...
and
ethylene oxide molecules. A
banana bond
In organic chemistry, a bent bond, also known as a banana bond, is a type of covalent chemical bond with a geometry somewhat reminiscent of a banana. The term itself is a general representation of electron density or configuration resembling a ...
model explains bonding in such compounds. Aziridine is less
basic
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
than
acyclic aliphatic amines, with a
pKa
PKA may refer to:
* Professionally known as:
** Pen name
** Stage persona
* p''K''a, the symbol for the acid dissociation constant at logarithmic scale
* Protein kinase A, a class of cAMP-dependent enzymes
* Pi Kappa Alpha, the North-American so ...
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
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
Organosulfates are a class of organic compounds sharing a common functional group with the structure R-O-SO3−. The SO4 core is a sulfate group and the R group is any organic residue. All organosulfates are formally esters derived from alcohols ...
, 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.]
See also
* Binary ethylenimine, a dimeric form of aziridine
References
{{Commonscat
Functional groups
IARC Group 2B carcinogens
Aziridines