In nature, there are millions of carbon compounds present. A standardised method of naming has been developed to specifically classify them and is recognised as the nomenclature scheme of the IUPAC (International Union of Pure and Applied Chemistry). For different compound families and compounds of multiple functional groups, this course module addresses the rules for IUPAC nomenclature. The chemical nomenclature of newly found elements or compounds is determined by them.

Functional groups define the properties and reactivity of organic molecules. Functional groups are groups of atoms attached to the main carbon chain or side chains. In organic and biological chemistry, the most frequently found classes of atoms are called functional groups. It is beneficial to be able to identify these groups, to understand what they are called, and to understand how to name particular compounds containing these groups.

IUPAC Nomenclature of Organic Compounds

Nomenclature of Organic Compounds follows recommendations of IUPAC in naming organic compounds, carbocations, etc. The IUPAC charged a committee with the task of establishing a systematic way to name organic compounds. The resulting system which has been refined over the years. However the most important aspects of these nomenclature rules are

Rule – 1: Identify the longest chain, the one with the greatest number of carbons, neglecting branches. This determines the root name of the compound. If two chains have the same number of carbons, select the one with the greater number of branch points.

Rule – 2: Number the carbon in this longest chain, starting at the end nearest the first branch point.

Rule – 3: Identify the location and type of each substituent. Add the information as a prefix to the root name.

When viewing a simplified formula, it is important to acknowledge that all parentheses are used to define repeated units. The cycloalkane to be used as the parent chain is determined by the IUPAC Nomenclature. The one with the largest number of carbon atoms is the parent chain. If there are two cycloalkanes, use the higher-carbon cycloalkane as the parent chain. The aim of the IUPAC nomenclature system is to create, in order to promote cooperation, an international standard for naming compounds.

Functional Group in Organic Chemistry

The groups of atoms that are bound to the carbon backbone of organic molecules are functional groups. Functional groups are responsible for organic compounds’ signature chemical reactions. They are less stable and more likely to partake in chemical reactions than the carbon backbone. An atom or group of atoms that is responsible for a specific chemical property of an organic compound is a functional group. It is possible to classify organic compounds according to their functional groups.

Only the elements carbon and hydrogen form the simplest organic compounds, and they are considered hydrocarbons. There is a wide range of hydrocarbons, since they are composed of just two kinds of atoms, and they may consist of different lengths of strings, branched chains, and carbon atom rings, or variations of these configurations. The molecule is assigned its properties by the functional group, independent of what molecule it contains. They are chemical reactivity centres.