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What is the meaning of Amines? Concept, Definition of Amines

Definition of amines

1 Meaning of amines

Amines are organic chemical compounds that are considered as derivatives of ammonia and result from the replacement of the hydrogen molecule by radicals for rent. According to one, two or three hydrogens are replaced, the amines respectively are primary, secondary, or tertiary.
There are different types of amines:
-Primary amines - Amines secondary - tertiary amines

Ammonia Primary amine Secondary amine Tertiary amine
Ammonia.svg Amina1.png Amina2.png Amina3.png


• Primary amines: aniline,...
• Secondary amines: diethylamine, etilmetilamina,...
• Tertiary amines: dimetilbencilamina,...
Amines are simple alkyl groups are equal and mixed if these are different.
Amines are very polar compounds. Primary and secondary amines can form hydrogen bonds. Pure tertiary amines cannot form hydrogen bonds, however can accept hydrogen bonds with molecules containing n-h or o-h links. As nitrogen is less electronegative than oxygen, the n-h bond is less polar than the o-h bond. Therefore, the amines form hydrogen bridges weaker than alcohols of similar molecular weights.
Primary and secondary amines have boiling points lower than the spirits, but greater than the of similar molecular weight ethers. Tertiary amines, without hydrogen bonds, have boiling points lower than primary and secondary amines of similar molecular weights.


Amines are classified according to the number of hydrogen atoms of ammonia are replaced by organic groups. Those who have a single group are called primary amines, which have two are called secondary amines and having three, tertiary amines.
When prefixes are used di, tri, is indicated if it is an amine secondary and tertiary, respectively, with groups or radicals equal. When it comes to these different groups are named starting with children and ending with the highest to which is added the termination amine. Sometimes indicates the prefix amino indicating the position, over the name of the hydrocarbon.

2. Definition of amines

Amines are substances, derived from ammonia, characterized as polar in moderation, with a higher boiling point than the alkanes but inferior to the point of alcohols. On hydrogen atom, amines possess a pair of non-shared electrons. As deemed replaced one, two or three atoms of hydrogen radical alkyl or aryl, primary, secondary and tertiary, amines arise respectively. If they are replaced by aril appear aromatic amines.
In primary and secondary amines, their molecules can be with the water and each other, strong hydrogen bonds. The tertiary, only with water but not each other, therefore the latter to boil at lower temperature than the first, even if they have a comparable molecular weight. Low-molecular-weight amines, are very soluble in water.
By its nature Nucleophilic, due to the couple of non-shared electrons from the atom of nitrogen and its basicity, they are reactive. The primary and secondary result in alquiloamonicas salts react with halides of alkyl, forming sulfonamides when they react with chlorides sulfonic acids; and all of them are water soluble ammonium salts react with inorganic acids. The tertiary non-reactive with nitrous acid.
The designation of primary amines is formed by specifying the organic Group attached to the nitrogen adding termination "amina" (Methylamine, ethylamine, benzene, Pert-Butylamine, Benzylamine and Allylamine). As secondary and tertiary amines are designated organic groups, individual mode or using the prefixes di or tri, if they are the same. (Methyl ethyl amine, diethylamine, Di-sec-butyl-acetate, Etilbencilamina, triethylamine).
Salts of amines and quaternary ammonium compounds, names are made up by adding the name of the anion, ammonium completion, for example trimethylammonium bromide.

3 Concept of amines

Amines are organic compounds derived from ammonia (NH3), and the replacement of the hydrogen that make up the ammonia groups rent or aril.
Amines are classified according to the number of substituents attached to primary amines and secondary amines and tertiary nitrogen.

Primary amine

Primary aromatic amine

Secondary amine

Physical properties:

Amines are colorless compounds that oxidize easily allowing are colored compounds. The first members of this series are gases with ammonia-like odor. As it increases the number of carbon atoms in the molecule, the odor is similar to the fish. Aromatic amines are very toxic are absorbed through the skin.

Aromatic amine secondary

Aromatic tertiary amine

Solubility: Primary and secondary amines are compounds polar, capable of forming hydrogen bonds among themselves and with water, this makes them soluble in it. The solubility decreases in molecules with more than 6 carbon atoms and those with the aromatic ring.

Boiling point:
The boiling point of amines is higher than the of the composite apolares that have the same molecular weight of amines. Nitrogen is less electronegative than oxygen, making bridges of hydrogen bonds between amines are given to a lesser extent than in spirits. This makes the boiling point of amines is lower than that of the spirits of the same molecular weight.

Chemical properties:

Amines behave as bases. When an amine is dissolved in water, it accepts a proton forming an ion alkyl-ammonium.

Synthesis of amines: Amines can be obtained treating halogenated derivatives or alcohol with ammonia.

Production of amines from halogenated derivatives

Lower amines are prepared commercially by passing vapours of alcohol in the presence of k or hot aluminium oxide and ammonia.

The reduction of various compounds such as nitroderivados, nitriles, aldehydes or ketones also has among its final products amines.


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