Question

$IUPAC$ name of the given compound is?

• A. $4-$ hydroxy$1$ methyl pentanoic acid
• B. $4-$ hydroxy$2$ methyl pentanoic acid
• C. $2-$ hydroxy $4$ methyl pentanoic acid
• D. $2-$ hydroxy $2$ methyl pentanoic acid

Answer 1

The correct option is B $4-$ hydroxy$2$ methyl pentanoic acid

Rules for Naming Hydrocarbons:-

Rule-I Selection of the longest carbon chain.

Rule-II Numbering the longest chain: Longest chain is numbered starting from a terminal carbon. Numbering is done is such a way that lowest possible number is given to the side chain or a functional group.

Rule-III Writing names of branched, saturated hydrocarbons, locants are written first in alphabetical order followed by name of parent chain.

Rule-IV Some common names are retained in $IUPAC$ system for unsubstituted hydrocarbon only.

(Refer to Image 1)

$-COOH$ group is given preference while numbering than $-OH$ group. So,

(Refer to Image 2)

$4-hydroxy-2-methyl-pentanoic$ $acid$.