What is the correct IUPAC name for a compound with the structure commonly referred to as $2$-methyl-$4$-($1$-methylethyl)octane?

• A. $4$-(1-methylethyl)-2-methyloctane
• B. $4$-(1-methylethyl)-2-methyloctane is named as $4$-isopropyl-2-methyloctane according to IUPAC rules
• C. $4$-isopropyl-2-methyloctane
• D. $4$-isopropyloctane

Answer: (B)

Verified step by step guidance

1. Identify the longest continuous carbon chain in the molecule, which in this case is an octane (8 carbons). This forms the parent name of the compound.
2. Number the carbon chain from the end nearest to the first substituent to give the substituents the lowest possible numbers. Here, substituents are at carbons 2 and 4.
3. Recognize the substituents attached to the main chain: at carbon 2, there is a methyl group, and at carbon 4, there is a (1-methylethyl) group.
4. Convert the substituent name (1-methylethyl) to its correct IUPAC substituent name. The group (1-methylethyl) is commonly known as an isopropyl group, so rename it as 'isopropyl'.
5. Combine the substituent names with their position numbers and the parent chain name to form the correct IUPAC name: '4-isopropyl-2-methyloctane'.