Amines

Amines are commonly drawn as the structure below (R- being any alkyl group attached):

Figure 1

Amines have a classification of primary, secondary, or tertiary-- as drawn below respectively:

Figure 2

Amines are named by naming the alkyl group, or groups, that are attached to the nitrogen and then following that name with the word amine. More complicated structures are often named using the prefix amino- , meaning the word amino comes before the naming of the alkyl structure or structures.

Figure 3

Amines in which the nitrogen is attached to an aromatic ring (commonly referred to as aromatic amines) are named using the ending aniline. However the special structure aminotoluene is more appropriately called toluidine. Examples are as follows:

Figure 4

As a side note, amines that are secondary or tertiary to aromatic rings (as seen below), remain with the ending amine to the rest of the structure.

Figure 5

Salts of amines generally are named by replacing the ending amine with ammonium (or aniline with anilinium), then adding the name of the anion (such as chloride or sulfate) at the very end. Examples:

Figure 6

Physical Properties of Amines

Amines are polar compounds. Amines have higher boiling points than non-polar compounds of the same molecular weight, yet alcohols and carboxylic acids are still higher. Amines are capable of forming hydrogen bonds with water, and are thus (smaller) amines are very soluble in water. However, as is expected, amines are less soluble in solvents such as ether or alcohol. Amines of methane and ethane smell very much like ammonia. Other amines of higher alkyl groups have fish odors. Aromatic amines are extremely toxic.