Which of the following is the correct IUPAC name for a benzene ring with a bromine substituent at position $4$, a chlorine substituent at position $2$, and a hydroxyl group at position $1$?

• A. $4$-bromo-$2$-chlorophenol
• B. $2$-bromo-$4$-chlorophenol
• C. $2$-chloro-$4$-bromobenzyl alcohol
• D. $2$-bromo-$4$-chlorophenol

Answer: (A)

Verified step by step guidance

1. Identify the parent compound: Since there is a hydroxyl group (-OH) attached to the benzene ring, the parent compound is phenol.
2. Number the benzene ring starting from the hydroxyl group as position 1, because the -OH group has the highest priority in naming according to IUPAC rules.
3. Assign numbers to the substituents bromine (Br) and chlorine (Cl) based on their positions relative to the hydroxyl group. Here, chlorine is at position 2 and bromine is at position 4.
4. List the substituents in alphabetical order in the name, regardless of their position numbers. Between 'bromo' and 'chloro', 'bromo' comes before 'chloro'.
5. Combine the substituents with their position numbers and the parent name 'phenol' to form the full IUPAC name: \$4\(-bromo-\)2$-chlorophenol.