Question

The IUPAC name of the following alkane is \(CH_3-CH_2-CH(C_2H_5)-CH_2-CH(CH_3)-CH_2-CH_3\)

• A. 3-methyl-5-ethylheptane
• B. 3,5-diethylhexane
• C. 4,6-diethylhexane
• D. 3-ethyl-5-methylheptane
• E. 3-ethyl-5,6-dimethylhexane

Hint:

Always expand alkyl groups like \(C_2H_5\) mentally to make sure you've found the truly longest chain. In this case, the horizontal chain was the longest anyway.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
IUPAC naming follows the longest continuous carbon chain rule and alphabetical order for substituents.

Step 3: Detailed Explanation:
1. Longest Chain: Identify the longest carbon chain.
\(C_1H_3-C_2H_2-C_3H(C_2H_5)-C_4H_2-C_5H(CH_3)-C_6H_2-C_7H_3\).
The longest chain has 7 carbons, so the root name is heptane.
2. Numbering: If we number from left: substituents are at 3 (ethyl) and 5 (methyl).
If we number from right: substituents are at 3 (methyl) and 5 (ethyl).
3. Alphabetical Rule: Ethyl comes before Methyl alphabetically. Thus, we give the lower number (3) to the ethyl group.
Name: 3-ethyl-5-methylheptane.

Step 4: Final Answer:
The name is 3-ethyl-5-methylheptane.