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 ascertain the IUPAC nomenclature for the compound:
\[\text{CH}_3 - \text{CH}_2 - \text{CH}(\text{CH}_3) - \text{CH}_2 - \text{CH}_3\]
the following procedures are applied:

1. Ascertain the longest uninterrupted carbon sequence. This sequence comprises five carbon atoms, constituting a "pentane" backbone.
2. Assign numerical designations to the carbon atoms within the sequence, ensuring that any attached groups are assigned the lowest feasible numerical values. Numbering commences from the terminus nearest to the substituent:
   \(C_1 - CH_3, C_2 - CH_2, C_3 - CH(CH_3), C_4 - CH_2, C_5 - CH_3\).
3. Recognize and designate the substituents. A single methyl group is affixed to the third carbon atom.
4. Integrate the substituent's designation with the foundational nomenclature of the carbon sequence:
   The "methyl" substituent is located on carbon 3, and the sequence is a pentane, yielding the IUPAC name "3-Methylpentane".

Consequently, the definitive IUPAC designation for the compound is 3-Methylpentane.