Amine

From open-encyclopedia.com - the free encyclopedia.

Ammonia

Amines are organic compounds containing nitrogen as the key atom in the amine functional group. Amines have structures resembling ammonia, where one or more hydrogen atoms are replaced by alkyl groups or other groups where the nitrogen is bonded to a carbon atom in the group (groups symbolized by R below). However, if any of the carbons bonded to the nitrogen is part of a carbonyl group, then the compound is considered an amide rather than an amine.

See the Category:Amines for a list of types of amine and some real examples of this class of chemical.

As shown in the following pictures, if only one the hydrogens in ammonia is replaced by a carbon based group, then it is a primary amine. If two of the hydrogens are replaced by two carbon based groups, then it is a secondary amine. If all three hydrogens are replaced with three carbon based groups, then it is a tertiary amine.

Primary Amine:
image:amina1.png

Secondary Amine:
image:amina2.png

Tertiary Amine:
image:amina3.png

Naming:

Lower amines are named with the suffix -amine.

image:methylamine.png
Methylamine

Higher amines have the prefix amino as a functional group.

image:2-amino-pentane.png
2-amino-pentane

Properties:

Like ammonia, amines act as bases. The nitrogen atom has a lone electron pair available which can accept a H⁺ ion to bond to the nitrogen forming a positive substituted ammonium ion.

Also, a halogenoalkane can react with an amine to form a corresponding alkyl-substituted amine, with the release of a halogen acid.

If the reacting amine is a tertiary amine in such a reaction, then a positive quaternary ammonium ion will be formed along with a negative halide ion.

These sort of paired ion compounds are called quaternary ammonium salts.

Because they are basic, amines can neutralize carboxylic acids to form the corresponding substituted ammonium carboxylate salts. Upon heating to 200^o C, these salts will dehydrate to form amides, if the initial amine was primary or secondary. Derivatives of carboxylic acids, such as acyl chlorides, can react with primary or secondary amines to form amides.

The volatile amines have strong unpleasant smells. Some have fishy smells.

Aromatic amines

Aromatic amines are amines in which the nitrogen is bonded to an aromatic ring (such as a benzene ring). The aromatic ring affects the basicity of the amine.

de:Amine es:Amina fr:Amine he:אמין(כימיה) nl:Amine ja:アミン pl:Amina sv:Amin