19.2 : Nomenclature of Primary Amines

Primary, secondary, and tertiary amines are compounds consisting of one, two, and three alkyl groups connected to the amino group (–NH₂), respectively. As depicted in Figure 1, the common name of the primary amines is obtained by adding the suffix -amine to the alkyl substituent attached to the amino group as the corresponding alkylamine.

Figure 1. Structure and nomenclature of some popular primary amines.

In IUPAC nomenclature for primary amines, the final -e of the parent alkane is replaced with the suffix -amine to give the corresponding alkanamines. Here, the longest parent alkane hydrocarbon chain bound to the amine nitrogen is selected such that the carbon atom attached to the amine nitrogen is assigned the lowest locant. Subsequently, the substituents and their locant values are listed alphabetically and prefixed to the parent name. Figure 2 provides two typical examples.

Figure 2. Representative examples for the nomenclature of primary amines.

Any chiral center, if present, is added as a prefix, and the chiral descriptors are added with the appropriate locant. Figure 3 depicts some representative examples of the same.

Figure 3. An illustration of the nomenclature of primary amines with chirality.

In molecules with multiple substituents, including the nitro group, it is given the lowest precedence, except for halogens. As depicted in Figure 4, amino- is prefixed to the parent name for the nomenclature of such compounds.

Figure 4. Nomenclature of primary amines with multiple functional groups.

As for the nomenclature of a molecule with two –NH₂ groups, the final -e of the parent alkane is retained, and the parent name is suffixed with -diamine. Alternatively, the primary amines bearing cyclic alkyl groups are suffixed with -amine replacing the final -e in the parent cycloalkane.

Figure 5. Nomenclature of amines with repeating amino groups or a cyclic alkyl group.