Question

Write IUPAC name of the following:

Answer 1

IUPAC system of nomenclature is a system of naming compounds in chemistry. IUPAC stands for International Union of Pure and Applied Chemistry. The $- {\text{COOH}}$ group is called carboxylic group and the $- {\text{N}}{{\text{H}}_2}$ group is called amino group. We have to find the parent chain initially whether it is a carboxylic group or amino group.

Complete step by step answer:
Carboxylic acids belong to a homologous series of organic compounds similar to alkanes, alkenes or alcohols. Aromatic compounds have many common names that have been accepted by IUPAC. Benzene has different types based on substitution-mono substituted, arenes, aryl, di substituted, multi substituted.
In the given compound, benzene is substituted with two groups, thus known as di substituted benzene. Each position of carbon is named differently. Relative positions on a di substituted benzene ring are:
-Ortho-$\left( {\text{o}} \right)$ on adjacent carbons $(1,2 -$di substituted)
-Meta-$\left( {\text{m}} \right)$ separated by one carbon $(1,3 -$di substituted)
-Para-$\left( {\text{p}} \right)$ separated by two carbons $(1,4 -$ di substituted)
The ortho, meta and para nomenclature is useful to describe reaction patterns.
Also we have to find the parent chain. If the compound has two substitutions, we have to check the priority order of functional groups. Acid has more priority than amino groups. So the root name or parent name is benzoic acid.
Here, the position in which $- {\text{COOH}}$ is placed is $1$ and the position of $- {\text{N}}{{\text{H}}_2}$ is placed is $3$ with respect to $- {\text{COOH}}$ group.
Therefore the IUPAC name of the compound is $3 -$ amino benzoic acid since the amino group is placed at third position.

Note:
Highest priority groups start from acids, sulfonic acids, esters, acid halides, amides, nitrile, aldehyde, ketone, alcohol, thiol, amine etc. This compound is also called meta amino benzoic acid because of the third position of the amino group with respect to the acid group.