CBSE Class 12-science Answered

The IUPAC system of nomenclature is a set of logical rules framed which are mainly aimed at giving an unambiguous name to an organic compound. By using this system, it is possible to give a systematic name to an organic compound just by looking at its structure and it is also possible to write the structure of organic compound by following the IUPAC name for that compound.

The systematic IUPAC name of an organic compound consists of four parts.

1. Root word
2. Suffix(es) and
3. Prefix(es)
4. infix

The complete systematic IUPAC name can be represented as:

* The root word and 1^osuffix together is known as base name. 

* The Prefix(es), infix and 2^o suffix may or may not be required always. 

1) The first step in giving IUPAC name to an organic compound is to select the parent chain and assign a root word. 

2) Next, the appropriate primary prefix(es) must be added to the root word to indicate the saturation or unsaturation.

3) If the molecule contains functional group or groups, a secondary suffix must be added to indicate the main functional group. This is optional and not necessary if the molecule containsno functional group.

4) Prefix the root word with the infix "cyclo" if the parent chain is cyclic; or with the infix "spiro" if it is a spiro compound; or with the infix "bicyclo" if the compound is bicyclic.

5) Finally add  prefix(es) to the name if there are side chains or substituents on the parent chain.

 

E.g. The IUPAC name of the following compound is arrived in steps mentioned below.