New amide alkaloid from the aerial part of Piper capense L.f. (Piperaceae)

Amines with low molecular weight are usually gaseous at room temperature, while those with high molecular weight are liquid or solids in nature. Usually, low molecular weight amines have a rotten fish-like smell. Diamines typically have a pungent smell. For instance, cadaverine and putrescine, depicted in Figure 1, are two molecules responsible for decaying tissue.

Amines are organic derivatives of ammonia. They are formed by replacing one or more ammonia protons with alkyl or aryl groups. Depending upon the number of organyl groups bonded to nitrogen, amines are classified as primary, secondary, or tertiary. Primary amines have one organyl group attached to the nitrogen atom, while secondary and tertiary amines have two and three organyl groups attached to the nitrogen atom, respectively.

Naming Amides
The IUPAC and common names of amides are derived from the parent carboxylic acid, by replacing the suffix “oic acid” and “ic acid,” respectively, with “amide.” In the following example, the IUPAC name ethanamide is derived from ethanoic acid, and the common name, acetamide, is obtained from acetic acid.

Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).

Carbonyl compounds and primary amines undergo reductive amination first to produce imines, followed by secondary amines in the same reaction mixture, using selective reducing agents like sodium cyanoborohydride or sodium triacetoxyborohydride. Reductive amination produces different degrees of substitution of amines depending on the starting amine substrate.

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.