Aziridine is an
organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
consisting of the three-membered
heterocycle
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...
. It is a colorless, toxic, volatile liquid that is of significant practical interest.
Aziridine was discovered in 1888 by the chemist
Siegmund Gabriel
Siegmund Gabriel (7 November 1851 – 22 March 1924) was a German chemist.
Scientific career
Siegmund Gabriel began studying chemistry at the University of Berlin in 1871. He continued his studies at the University of Heidelberg in 1872 wi ...
. Its derivatives, also referred to as
aziridines
220 px, chemotherapy.html" ;"title="Mitomycin C, an aziridine, is used as a chemotherapy">chemotherapeutic agent by virtue of its antitumour activity.
In organic chemistry, aziridines are organic compounds containing the aziridine functional gr ...
, are of broader interest in medicinal chemistry.
Structure
The
bond angle
Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometrical parameters that deter ...
s in aziridine are approximately 60°, considerably less than the normal
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...
bond angle of 109.5°, which results in
angle strain
In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles are su ...
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 triangular ring. The small size of the ring creates substantial ring strain in the structure. Cyclopropane ...
and
ethylene oxide
Ethylene oxide is an organic compound with the chemical formula, formula . It is a cyclic ether and the simplest epoxide: a three-membered ring (chemistry), ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless ...
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 or BASIC may refer to:
Science and technology
* BASIC, a computer programming language
* Basic (chemistry), having the properties of a base
* Basic access authentication, in HTTP
Entertainment
* Basic (film), ''Basic'' (film), a 2003 film
...
than
acyclic aliphatic
In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated (in which all ...
amines, with a
pKa
In chemistry, an acid dissociation constant (also known as acidity constant, or acid-ionization constant; denoted ) is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction
:H ...
of 7.9 for the
conjugate acid
A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid gives a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as it loses a hydrogen ion in the rever ...
, due to increased
s character of the
nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
free electron pair.
Angle strain
In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles are su ...
in aziridine also increases the barrier to
nitrogen inversion
In chemistry, pyramidal inversion (also umbrella inversion) is a fluxional process in compounds with a pyramidal molecule, such as ammonia (NH3) "turns inside out". It is a rapid oscillation of the atom and substituents, the molecule or ion pass ...
. 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 Aminoethanol may refer to:
* 1-Aminoethanol
* Ethanolamine
Ethanolamine (2-aminoethanol, monoethanolamine, ETA, or MEA) is a naturally occurring organic chemical compound with the formula or . The molecule is bifunctional, containing both a p ...
via two related routes. The Nippon Shokubai process requires an oxide catalyst and high temperatures to effect the dehydration. In the
Wenker synthesis
The Wenker synthesis is an organic reaction converting a beta amino alcohol to an aziridine with the help of sulfuric acid. It is used industrially for the synthesis of aziridine itself.
The original Wenker synthesis of aziridine itself takes ...
, the aminoethanol is converted to the
sulfate ester
In organosulfur chemistry, organosulfates are a class of organic compounds sharing a common functional group with the structure . The core is a sulfate group and the R group is any Organyl group, organic residue. All organosulfates are formally ...
, 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 ]polyethylenimine
Polyethylenimine (PEI) or polyaziridine is a polymer with repeating units composed of the amine group and two carbon Aliphatic_compound, aliphatic ''CHCH'' spacers. Linear polyethyleneimines contain all Amines#Classification_of_amines, secondary ...
s (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 Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting ...
, 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 Binary ethylenimine (BEI) is a preparation of aziridine. It can be produced by heating bromoethylamine hydrobromide or 2-aminoethyl hydrogen sulfate in the presence of sodium hydroxide ( Gabriel method). It contains at least one three-membered ring ...
, a dimeric form of aziridine
References
{{Commonscat
Functional groups
IARC Group 2B carcinogens
Aziridines
Substances discovered in the 19th century