Question

What is the IUPAC name for the compound \( \text{CH}_3 - \text{CH(OH)} - \text{CH}_2 - \text{CHO} \)?

• A. 3-Hydroxybutanal
• B. 2-Hydroxybutanal
• C. 4-Hydroxybutanal
• D. Butanol

Hint:

When aldehyde and alcohol groups are present together, aldehyde has higher priority and the \(-OH\) group is treated as a hydroxy substituent.

Answer 1

The Correct Option is A

Concept: In IUPAC nomenclature, the aldehyde group (\(-CHO\)) has higher priority than the alcohol group (\(-OH\)). Thus the aldehyde determines the parent chain and numbering starts from the \(-CHO\) carbon.

Step 1: Identify the longest carbon chain containing the aldehyde group. The compound contains 4 carbon atoms, so the parent chain is butanal. \[ CHO-CH_2-CH(OH)-CH_3 \]

Step 2: Number the carbon atoms. Numbering starts from the aldehyde carbon. \[ 1-CHO,\quad 2-CH_2,\quad 3-CH(OH),\quad 4-CH_3 \]

Step 3: Identify substituents. The \(-OH\) group is present at carbon 3. Thus the IUPAC name is: \[ \boxed{3\text{-Hydroxybutanal}} \]