Aromatics and heterocycles


In chemistry, all rings that do not only consist of carbon atoms are generally referred to as heterocycles. While the number of carbon atoms predominates in organic chemistry, there are also ring compounds in inorganic chemistry that contain only heteroatoms, i.e. no carbon.

In organic chemistry, heterocycles are rings in which at least one atom of the ring structure is not a carbon atom.

The most abundant heteroatoms in these rings in organic chemistry are nitrogen, oxygen and sulfur. However, rings with other elements such as phosphorus and selenium also occur. In nature, heterocycles are extremely important, so over half of all natural products contain heterocycles. Many of them are involved in important functions in the body or are pharmacologically active. The nitrogen-containing heterocycles are so widespread in nature that natural substances (alkaloids) form their own group. The blueprint of biological life is also formed by nitrogen-containing heterocycles. With the help of the nucleobases (pyrimidine and purine bases) the "program" of life is stored in the DNA and RNA.

Tab. 1
Examples of important heterocycles in nature




Uracil: A "letter" in DNA


DNA Section: The Text of Life

Why are the heterocycles so important in nature? To understand this better, it is important to consider their peculiarities with respect to the carbocycles. The most important difference between carbocycles and heterocycles is the uneven charge distribution among the heterocycles. In nature, this is a critical factor in molecular recognition, for example, of the base pairs of DNA.

Video: heteroaromatic compounds (December 2021).