Question

What is the IUPAC name of the compound: \[ \text{CH}_3 - \text{CH}_2 - \text{CH}(\text{CH}_3) - \text{CH}_2 - \text{CH}_3 \]

• A. 3-Methylpentane
• B. 2-Methylpentane
• C. 3-Methylbutane
• D. 2-Methylbutane

Hint:

Naming Tip: Number the carbon chain so that substituents get the lowest possible numbers.

Answer 1

The Correct Option is A

To determine the IUPAC name of the compound:
\[\text{CH}_3 - \text{CH}_2 - \text{CH}(\text{CH}_3) - \text{CH}_2 - \text{CH}_3\]
we follow these steps:

1. Identify the longest continuous carbon chain. Here, it is comprised of five carbon atoms, forming a "pentane" chain.
2. Number the carbon atoms in the chain such that substituents receive the lowest possible numbers. Starting from the end closest to the substituent, we number the chain: 
   \(C_1 - CH_3, C_2 - CH_2, C_3 - CH(CH_3), C_4 - CH_2, C_5 - CH_3\).
3. Identify and name the substituents. There is one methyl group attached to carbon 3.
4. Combine the substituent name with the base name of the carbon chain: 
   The substituent "methyl" is on carbon 3, and the chain is a pentane, resulting in the IUPAC name "3-Methylpentane".

Therefore, the correct IUPAC name of the compound is 3-Methylpentane.

Answer 2

The compound given is:
\[\text{CH}_3 - \text{CH}_2 - \text{CH}(\text{CH}_3) - \text{CH}_2 - \text{CH}_3\] To determine the IUPAC name, follow these steps:

1. Identify the longest carbon chain in the compound. In this case, it is a chain of five carbons: \[\text{CH}_3 - \text{CH}_2 - \text{CH} - \text{CH}_2 - \text{CH}_3\]
2. Name this chain as pentane, since it has five carbon atoms.
3. Identify the substituents attached to the main chain. There is a methyl group \(\text{CH}_3\) attached to the third carbon of the main chain.
4. Number the carbon atoms in the main chain starting from the end nearest to the substituent, which is the methyl group. The numbering is then: 1, 2, 3, 4, 5.
5. Combine the information to give the IUPAC name: The methyl group is attached to the third carbon, resulting in the name 3-Methylpentane.

The correct IUPAC name is therefore: 3-Methylpentane.