Give a systematic name for the below compound.

• A. 1-sec-butyl-3-methylcyclopentane
• B. 1-methyl-3-sec-butylcyclopentane
• C. 1-butyl-3-methylcyclopentane
• D. 1-methyl-3-butylpentane

Answer: (A)

Verified step by step guidance

1. Identify the parent structure: The main ring is a cyclopentane, which is a five-membered carbon ring.
2. Number the ring carbons to give the substituents the lowest possible numbers. Start numbering at the carbon with the substituent that comes first alphabetically or gives the substituents the lowest locants. Here, numbering starts at the carbon with the sec-butyl group to give it position 1.
3. Identify and name the substituents attached to the ring. There is a methyl group (–CH3) and a sec-butyl group (a four-carbon substituent attached via its secondary carbon).
4. Assign the positions of the substituents on the ring. The sec-butyl group is at carbon 1, and the methyl group is at carbon 3.
5. Combine the substituent names and positions with the parent name to form the systematic name: 1-sec-butyl-3-methylcyclopentane.