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AMINES
Amine is a type of compound that is derived from ammonia (NH3). In other words, we can simply say that amines are derivatives of ammonia.
Some of the naturally occurring amines include alkaloids found in certain plants; catecholamine neurotransmitters (i.e. dopamine, epinephrine, and norepinephrine); and a specific chemical mediator, histamine, existing in most animal tissues. Common examples of amines include amino acids, trimethylamine, and aniline. Meanwhile, inorganic ammonia compounds such as monochloramine (NClH2) are also called amines.
An amine is generally a functional group with a nitrogen atom having a lone pair. Amines resemble ammonia structurally where nitrogen can bond up to 3 hydrogen atoms. Generally, in amines, hydrogen atoms are substituted by an aryl or alkyl group.
Compounds of nitrogen connected to a carbonyl group are called as amides, they have a structure R–CO–NR′R″ and varies in properties with amines.
Alkyl Amines
Alkylamines consist of tetrahedral nitrogen centres. Here the C-N-C and C-N-H bond angle is 109 °. The distance between C-N is smaller compared to the C-C range. The amines can also have a chiral property where the centre of nitrogen holds four replacements that create the lone pairs.
Aromatic Amines
Nitrogen almost has a planar structure in aromatic amines (“anilines”). This is due to the mixture of the lone pair with the aryl substituent. The C-N range is shorter. For aniline, the distance between C-N is the same as the distances between C-C.
Examples:
- H2N –(CH2)6– NH2 (Hexane -1,6-diamine or 1,6-hexane diamine)
Occurrence of Amines
Naturally, amines occur in proteins, vitamins, hormones, etc. and they are also prepared synthetically to make polymers, drugs, and dyes.
Uses of Amines
Amines have a widespread application in our daily lives. Some uses of amines are listed below:
It is used in water purification, medicine manufacturing and development of insecticides and pesticides.
It is involved in the production of amino acids which is the building block of proteins in living beings. Many varieties of vitamins are also made by amines.
Serotonin is an important amine that functions as one of the primary neurotransmitters. It controls the feelings of hunger and is critical for the speed with which the brain operates in general.
Pain-relieving medicines such as Morphine and Demerol which are also known as analgesics are made from amines.
On the basis of how the hydrogen atoms are replaced by an ammonia molecule, amines can be divided into 4 types.
Primary Amines
When one of the hydrogen atoms of the ammonia molecule is replaced by an alkyl or aryl group. Eg: Methylamine CH3NH2, Aniline C6H5NH2
Secondary Amines
Two organic substituents replace the hydrogen atoms of the ammonia molecule forming an amine. Eg: Dimethylamine (CH3)2NH, Diphenylamine (C6H5)2NH
Tertiary Amines
When all 3 of the hydrogen atoms are replaced by an organic substituent, it could be an aryl or aromatic group. Eg: Trimethylamine N(CH3)3, Ethylenediaminetetraacetic acid (EDTA)
Cyclic Amines
These are secondary or tertiary amines in an aromatic ring structure. Eg: Piperidine (CH2)5NH, Aziridines C2H5N