Question

The IUPAC name of the compound $C{H_3} - CH\left( {OH} \right) - COOH$ is:
A) Lactic acid
B) 2-hydroxy propanoic acid
C) 3-hydroxy propanoic acid
D) Carboxy propanol

Answer 1

To answer this question, you must recall the rules for IUPAC nomenclature of a compound. While numbering, the functional group with the highest priority should get the smallest number.

Complete step by step solution:
We must follow the rules for the IUPAC nomenclature. These rules make sure that each compound has a different unique name.
First of all, we mark the longest chain, then identify the group attached to the chain. The next step involves the numbering of the group in such a way that the carbon to which the substituent group is present has the lowest number. Then we must determine the functional group with the highest property to be used as a suffix and other components are arranged alphabetically in the name of the compound.
The functional group attached to the main carbon chain is a carboxylic acid group and thus we start the numbering of the chain from that carbon. There are a total of three carbon atoms in the chain so the word root for the compound will be prop-.
At the second carbon, we have a hydroxyl group as well which will be the prefix hydroxyl- before the word root. The primary suffix will be –ane as there are no carbon carbon double bonds in the chain while the secondary suffix will be of the functional group acid (-oic acid)
Thus, the IUPAC name of the compound can be written as 2-hydroxy-propanoic acid.

Thus, the correct answer is B.

Note:
The order of preference for choice of the principal functional group is:
$- COOH > - S{O_3}H > - {(CO)_2}O > - COOR > - COX > - CON{H_2} > - CN$
$> - CHO > \rangle C = O > - OH > - SH > - N{H_2} > - OR > \rangle C = C\langle > - C \equiv C -$