Question

What is the correct IUPAC name of $HOOC-C{{H}_{2}}-COOH$?

Answer 1

For molecules with two carboxylic acid groups the longest chain is the carbon chain in between the two carboxyl groups including carboxylic carbon atoms. The suffix -dioic acid is used. General IUPAC name for dicarboxylic acid is Alkanedioic acid.

Complete step by step solution:
-In the IUPAC system of nomenclature, the name of an organic compound is derived by identifying the parent chain and functional group attached to it.
-Following are rules for naming an organic compound:
-First, the longest carbon chain in molecules is identified. Longest chain is considered the parent chain.
-The longest chain of carbon atoms containing a functional group is numbered in such a way that the functional group attached to the carbon atom possesses the lowest possible number in the chain.
-Numbering should be done in such a way that branched carbon atoms will get the lowest possible numbers.
-position of the substituent is indicated by appropriate numbers.
-If two or more identical substituents are present then numbers are separated by a comma.
-Molecules having two carboxylic acid groups, the longest chain is the carbon chain between two carboxyl groups including carboxylic carbon atoms.

-As there are two carboxylic groups, the numbering can be done in two ways. In both ways, carboxylic groups are numbered as 1 and 3.
As there are three carbon atoms including carboxylic acid groups, prefix alkane is propane.

The correct IUPAC name of $HOOC-C{{H}_{2}}-COOH$ is Propane-1,3-dioic acid.

Note: The longest chain of carbon atoms containing a functional group is numbered in such a way that the functional group attached to the carbon atom possesses the lowest possible number in the chain. Name of alkyls group attached as branch are then prefixed to name of parent.