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 alkyl groups need not be the same (indicted by the ', or '' behind the R), and may contain other functional 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 name it as an alkyl amine (note the spaces between the words), 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
methyl amine
or
methanamine
ethyl amine
or
ethanamine
 propyl amine
or
propanamine
2-propyl amine
or
2-propanamine
cyclobutyl amine
or
cyclobutanamine
1,2-ethyl diamine
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 (alkyl amine 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 dialkyl amine.

Examples naming simple secondary amines:

Compound Name
Line Drawing
3D Model
N-methylmethyl amine
or
N-methylmethanamine
or
dimethyl amine
N-methylethyl amine
or
N-methylethanamine
 N-ethylethyl amine
or
N-ethylethanamine
or
diethyl amine
N-methyl-2-propyl amine
or
N-methyl-2-propanamine
N-isopropylcyclobutyl amine
or
N-isopropylcyclobutanamine
N,2-dimethyl-3-pentyl amine
or
N,2-dimethyl-3-pentanamine


3) Tertiary Amines:

Similar to the secondary amines, the longest chain of carbons takes the root name (alkyl amine or alkanamine) and the other chains become 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 trialkyl amine.

Examples naming simple tertiary amines:

Compound Name
Line Drawing
3D Model
N,N-dimethylmethyl amine
or
N,N-dimethylmethanamine
or
trimethyl amine
N,N-dimethylethyl amine
or
N,N-dimethylethanamine
 N-ethyl-N-methylethyl amine
or
N-ethyl-N-methylethanamine
N-ethyl-N-methyl-3-hexyl amine
or
N-ethyl-N-methyl-3-hexanamine


Amines as Substituents:

In more complex molecules with multiple substituents, or ones containing higher priority functional groups, the amine is named as an amino- substituent. It is located by numbering the longest chain of carbons (containing the functional groups of interest) and locating the NH2 group by this numbering scheme (if the amino group is the highest priority group, it should have the lowest possible number). Secondary and tertiary amines are named by the above conventions.

A few examples of naming amines as substituents:

Compound Name
Line Drawing
3-amino-2,6-dimethyl-4-propyloctane
N-methyl-1-amino-2,3,3-trimethylcycloheptane


Tutorial Quiz: Amines

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