Amines contain one or more organic groups bonded to nitrogen; they have the general formulas RNH2, R2NH, and R3N.

Amines are organic derivatives of ammonia (NH3). In general, they are classified as primary (1°), secondary (2°), or tertiary (3°), according to how many organic groups are individually bound directly to the nitrogen atom.

Quaternary ammonium ion is a positive ion with four organic groups bonded to the nitrogen atom (R4N+).

Properties of amines:

• Primary and secondary amines can hydrogen-bond with each other and thus are higher boiling than alkanes but lower boiling than alcohols, due to weaker hydrogen bonds.

• Tertiary amines are lower boiling than secondary or primary amines because hydrogen bonding between tertiary amines is not possible.

• Methanamine, ethanamine, dimethylamine, and trimethylamine are gases; all other simple amines are liquids.

• Volatile amines usually have unpleasant odors.

• Simple amines (those with less than four carbons) are water-soluble due to their ability to hydrogen bonding with water.

• Amines are weak Bronsted–Lowry/Lewis bases .

• Many amines are physiologically active, and many are toxic.

Compounds that contain atoms other than carbon in the ring are known as heterocycles. Heterocyclic nitrogen compounds may be nonaromatic or aromatic. For example, piperidine, is a saturated heterocyclic amine with a six-membered ring.

Just like ammonia, aqueous solutions of amines are weakly basic because of the formation of OH- and R3NH+ ions in water.

In terms of basicity:

• Nonaromatic amines > Ammonia > Aromatic amines

Quaternary ammonium salt is an ionic compound composed of a quaternary ammonium ion and an anion.

Alkaloid is a naturally occurring, nitrogen-containing compound isolated from a plant. They are usually basic, bitter, and often poisonous.