Select the correct IUPAC name for the branched chain alkane.

Select the correct IUPAC name for the branched chain alkane. The name is: 3-propyl-5-ethyl-7-methyloctane 4-ethyl-6-ethyl-8-methylnonane 2-methyl-4,6-diethylnonane 4,6-diethyl-2-methylnonane

The Correct Answer and Explanation is:

Correct IUPAC Name:

2-methyl-4,6-diethylnonane

Explanation

To determine the correct IUPAC name of the given branched alkane, we need to follow the IUPAC rules for naming alkanes:

1. Find the longest continuous carbon chain:

From the image, the longest continuous carbon chain contains 9 carbon atoms, so the parent hydrocarbon is nonane.

2. Number the chain to give the lowest numbers to the substituents:

We must number the chain from the end closest to the first branch. Starting from the left side gives substituent positions at 2, 4, and 6, which are lower than numbering from the right.

3. Identify the substituents:

At carbon 2, there is a methyl group (–CH₃).
At carbon 4, there is an ethyl group (–CH₂CH₃).
At carbon 6, there is another ethyl group.

This gives us:

One methyl group at position 2.
Two ethyl groups at positions 4 and 6.

4. Assemble the name:

We use alphabetical order for substituents in the name:

Ethyl comes before methyl.
Two ethyl groups = diethyl → specify locations as 4,6-diethyl.
One methyl group at position 2 = 2-methyl.

Putting it all together:
2-methyl-4,6-diethylnonane

5. Verify the options:

Option A: Incorrect carbon count (octane = 8 C atoms).
Option B: Redundant “ethyl-ethyl” listing, and numbering incorrect.
Option C: ✅ Correct – matches our derived name.
Option D: Same name as C, but substituents not in proper alphabetical order.