Which of the following is the correct IUPAC name for a compound with a four-carbon chain, a bromine substituent on carbon $4$, and a ketone functional group on carbon $2$?

• A. $2-bromo-4-butanone$
• B. $1-bromo-2-butanone$
• C. $4-bromo-1-butanol$
• D. $4-bromo-2-butanone$

Answer: (D)

Verified step by step guidance

1. Identify the longest carbon chain containing the highest priority functional group. Here, the ketone group (C=O) is the highest priority, so the parent chain is a four-carbon chain named 'butanone'.
2. Number the carbon chain starting from the end nearest to the ketone group to give the ketone the lowest possible number. Since the ketone is on carbon 2, numbering should start from the end that places the ketone at C-2.
3. Locate the substituents on the chain. There is a bromine substituent on carbon 4, so it should be named as a 'bromo' substituent with the appropriate number indicating its position.
4. Combine the substituent and parent chain names, placing the substituent number and name before the parent name, separated by hyphens. The ketone position is indicated by the suffix '-2-one'.
5. Write the full IUPAC name as '4-bromo-2-butanone', ensuring correct order and numbering according to IUPAC rules.