Question

What is the IUPAC name for the compound \( CH_3 - CH(OH) - CH_2 - CHO \)?

• A. 3-hydroxybutanal
• B. 2-hydroxybutanal
• C. 4-hydroxybutanal
• D. 1-hydroxybutanal

Hint:

In compounds containing both \( -CHO \) and \( -OH \), the aldehyde group has higher priority and determines the suffix of the compound name.

Answer 1

The Correct Option is A

Concept: In IUPAC nomenclature:

• The highest priority functional group determines the suffix.
• The aldehyde group \( -CHO \) has higher priority than the alcohol group \( -OH \).
• Therefore, the compound will be named as a derivative of butanal.
• Numbering of the carbon chain begins from the aldehyde carbon.

Step 1: {Identify the longest carbon chain.} The compound has four carbon atoms: \[ CH_3 - CH(OH) - CH_2 - CHO \] Thus, the parent chain is butane.
Step 2: {Identify the principal functional group.} The aldehyde group \( -CHO \) has higher priority, so the base name becomes: \[ \text{butanal} \]
Step 3: {Number the carbon atoms.} Numbering starts from the aldehyde carbon. \[ CHO(1) - CH_2(2) - CH(OH)(3) - CH_3(4) \] Thus, the hydroxyl group is located at carbon \(3\).
Step 4: {Write the final IUPAC name.} Since the alcohol group acts as a substituent, it is written as hydroxy. \[ \text{3-hydroxybutanal} \]