What Are Heterocyclic Amines?

A cyclic chemical compound is composed of elemental atoms bonded together in the form of a ring. Most cyclic compounds are organic, containing carbon. A heterocyclic compound’s ring is composed of two or more different elements. Amines are complex organic compounds derived from the basic structure of ammonia, which is three hydrogen atoms bonded to a nitrogen. When these two types of compounds join, the resulting substances are collectively called heterocyclic amines.

Carbon binds together into a ringed structure, usually in configurations of five or six atoms, which adds to the versatility of the element. Furthermore, the ring remains stable when any of the carbon atoms are replaced by another element. Common combinations include sulfur, oxygen and nitrogen. These substitutions in a ring are called heteroatoms. A heterocyclic compound can be inorganic, but most contain at least one carbon atom.

Heterocyclic amines consist of at least one ring of two or more different elements. Bonded to this ring is at least one amine. From the basic structure of ammonia, one or more of its hydrogen atoms are replaced by what’s called a substituent. It can be a different element, or even a complex functional group of elements that would otherwise be unstable were it not bonded to the nitrogen atom. Most amines have a string structure and are base chemicals, also termed alkali, the opposite of acidic.

Many amines are fundamental to organic life. Amino acids, the building blocks of proteins that make all living tissues, are constructed from amines. When they are connected to a heterocyclic compound, however, their effects are quite variable and not completely understood. One example of a heterocyclic amine is thiamine, otherwise known as Vitamin B1. Other examples of heterocyclic amines are toxic carcinogens, known to cause cancer in humans.

In general, heterocyclic amines are categorized and studied based on three distinctive features. This includes which element or elements are its heteroatoms, how many atoms are in the heterocyclic ring, and the characteristics of its amine attachments. The nicotine in tobacco, for example, is an alkaloid carcinogen with one nitrogen and four carbon atoms in its ring, attached to another similar heterocyclic amine group. Nicotinic acid, also called niacin or vitamin B3, is built around a six-atom ring, and is essential to human life.

The chemical characteristics of amines attached to a heterocyclic ring fall into two classes: aromatic or aliphatic. Aromatic, or aryl, does not refer to smell, but rather the availability of electrons to migrate and spin around its attached cyclic ring. It renders the combined substance less alkaline, and more compatible with the acidic chemicals of the human body. Aliphatic, or alkyl, is more alkaline and presumably more toxic. An example of a heterocyclic aliphatic amine is the chemical responsible for the stench of rotting fish.