Basic Organic Nomenclature


Amines

Suffix:    amine

Prefix:    amino-

Amines are characterized by one to three alkyl groups being bonded to a central nitrogen atom (i.e. R-NH2, R-NH-R', R-N(-R')-R''). The alkyls groups need not be the same (indicted by the ', or '' behind the R), and may contain other function groups. The chemistry of these amines are all basically the same, depending on the polarization of the C-N bond, and the lone pair of electrons on the N. The three types of amines are designated as: primary (one alkyl group); secondary (two alkyl groups); or tertiary (three alkyl groups). Unfortunately there are several ways to name amines  depending on how many alkyl groups are attached to the nitrogen atom, or the presence of additional functional groups.


1) Primary Amines:

There are two basic methods for naming simple primary amines, the first is to named it as an alkylamine, and the second as an alkanamine (note, the terminal e of the alkane root is dropped).

Examples naming simple amines:

Compound Name
Line Drawing
3D Model
methylamine
or
methanamine
ethylamine
or
ethanamine
 propylamine
or
propanamine
2-propylamine
or
2-propanamine
cyclobutylamine
or
cyclobutanamine
1,2-ethyldiamine
or
1,2-ethanediamine *

* Because the suffix here is -diamine which starts with a consonant, the terminal -e of the alkane name is retained.


2) Secondary Amines:

The longest chain of carbons takes the root name (alkylamine or alkanamine) and the other chain becomes a substituent, located in the chain as being attached to the N. The N is considered to be a lower locant than numerical locants, and so is placed ahead of them. When the two alkyl groups are the same it can also be named as a dialkylamine.

Examples naming simple secondary amines:

Compound Name
Line Drawing
3D Model
N-methylmethylamine
or
N-methylmethanamine
or
dimethylamine
N-methylethylamine
or
N-methylethanamine
 N-ethylethylamine
or
N-ethylethanamine
or
diethylamine
N-methyl-2-propylamine
or
N-methyl-2-propanamine
N-isopropylcyclobutylamine
or
N-isopropylcyclobutanamine
N,2-dimethyl-3-pentylamine
or
N,2-dimethyl-3-pentanamine


3) Tertiary Amines:

Similar to the secondary amines, the longest chain of carbons takes the root name (alkylamine or alkanamine) and the other chains become a substituents located on the N. In this case, with two substituents on the N atom it will become a N,N- amine. When the three alkyl groups are the same it can be named as a trialkylamine.

Examples naming simple tertiary amines:

Compound Name
Line Drawing
3D Model
N,N-dimethylmethylamine
or
N,N-dimethylmethanamine
or
trimethylamine
N,N-dimethylethylamine
or
N,N-dimethylethanamine
 N-ethyl-N-methylethylamine
or
N-ethyl-N-methylethanamine
N-ethyl-N-methyl-3-hexylamine
or
N-ethyl-N-methyl-3-hexanamine


Amines as Substituents:

In more complex molecules with  higher priority functional groups, the amine is named as an amino- substituent. Examples of these will be given in subsequent pages.


Tutorial Quiz: Amines

Next Page: Thiols

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