Question

The IUPAC name of the following compound is:

• A. 4-Bromo-3-cyanophenol
• B. 2-Bromo-5-hydroxybenzonitrile
• C. 2-Cyano-4-hydroxybromobenzene
• D. 6-Bromo-3-hydroxybenzonitrile

Answer 1

The correct option is B

2-Bromo-5-hydroxybenzonitrile

Given compound has 3 substituents on a benzene ring. There are two candidates for the primary functional group $\to$ the $-CN$ group and the $-OH$ group. Also, there is a $-Br$ substituent.

Here $-CN$ will be the primary functional group as $-CN$ has a higher precedence over $-OH$ group. So the lowest number is given to carbon attached the $-CN$ group. The numbering proceeds to give the lowest number to the carbon atom at the first point of difference. In other words, lowest set of locants after naming C1 (attached to $-CN$ group).

Hence the correct numbering is as follows:

So the IUPAC of the given compound is

(b) 2-Bromo-5-hydroxybenzonitrile