an introduction to amines

The easiest way to think of amines is as near relatives of ammonia, NH3.

In amines, the hydrogen atoms in the ammonia have been replaced one at a time by hydrocarbon groups. On this page, we are only looking at cases where the hydrocarbon groups are simple alkyl groups.

The different kinds of amines

Amines fall into different classes depending on how many of the hydrogen atoms are replaced.

Primary amines

In primary amines, only one of the hydrogen atoms in the ammonia molecule has been replaced. That means that the formula of the primary amine will be RNH2 where “R” is an alkyl group.

Examples include:

Naming amines can be quite confusing because there are so many variations on the names. For example, the simplest amine, CH3NH2, can be called methylamine, methanamine or aminomethane.

The commonest name at this level is methylamine and, similarly, the second compound drawn above is usually called ethylamine.

Where there might be confusion about where the -NH2 group is attached to a chain, the simplest way of naming the compound is to use the “amino” form.

For example:

Secondary amines

In a secondary amine, two of the hydrogens in an ammonia molecule have been replaced by hydrocarbon groups. At this level, you are only likely to come across simple ones where both of the hydrocarbon groups are alkyl groups and both are the same.

For example:

There are other variants on the names, but this is the commonest and simplest way of naming these small secondary amines.

Tertiary amines

In a tertiary amine, all of the hydrogens in an ammonia molecule have been replaced by hydrocarbon groups. Again, you are only likely to come across simple ones where all three of the hydrocarbon groups are alkyl groups and all three are the same.

The naming is similar to secondary amines. For example: