Everything about Hemiaminal totally explained
A
hemiaminal is a
functional group or type of
chemical compound that has a
hydroxyl group and an
amine attached to the same
carbon atom: -C(OH)(NR
2)-. R can be
hydrogen or an
alkyl group. Hemiaminals are intermediates in
imine formation from an
amine and a
carbonyl by
alkylimino-de-oxo-bisubstitution.
An example is of an hemiaminal is that obtained from reaction of secondary amine
carbazole and
formaldehyde
Those generated from primary amines are unstable to the extent that they've never been isolated and very rarely been observed directly. In a 2007 study a hemiaminal substructure trapped in the cavity of a
host-guest complex was studied with a
chemical half-life of 30 minutes. Because both amine and carbonyl group are isolated in a cavity, hemiaminal formation is favored due to a high forward
reaction rate comparable to a
intramolecular reaction and also due to restricted access of external base (another amine) to the same cavity which would favor
elimination of water to the imine .
Hemiaminal formation is a key step in a
asymmetric total synthesis of
saxitoxin :
»
In this reaction step the
alkene group is first
oxidized to an intermediate
acyloin by action of
osmium(III) chloride,
oxone (
sacrificial catalyst) and
sodium carbonate (base).
Aminal
An
aminal or
aminoacetal is a
functional group or type of
chemical compound that has two
amine groups attached to the same
carbon atom: -C(NR
2)(NR
2)-. Again R can be
hydrogen or an
alkyl group.
The aminal and the hemiaminal groups are the cousins of
hemiacetals and
acetals with
nitrogen replaced by
oxygen. Aminals are encountered in for instance the
Fischer indole synthesis.
Further Information
Get more info on 'Hemiaminal'.
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