Q5 / 150 · MHT CET 2026 (19 April Shift 1) · Chemistry
Which from the following aldehydes contains two $-\text{CHO}$ groups in a molecule?
- AAcrolein
- BO-Tolualdehyde
- Correct answerCPhthaldehyde
- DButyraldehyde
Solution
Acrolein is $\text{CH}_2=\text{CH}-\text{CHO}$, which contains one $-\text{CHO}$ group.
o-Tolualdehyde is $o-\text{CH}_3-\text{C}_6\text{H}_4-\text{CHO}$, which contains one $-\text{CHO}$ group.
Phthaldehyde is benzene-1,2-dicarbaldehyde, $\text{C}_6\text{H}_4(\text{CHO})_2$, which contains two $-\text{CHO}$ groups.
Butyraldehyde is $\text{CH}_3-\text{CH}_2-\text{CH}_2-\text{CHO}$, which contains one $-\text{CHO}$ group.
Therefore, phthaldehyde contains two $-\text{CHO}$ groups.
Answer: Phthaldehyde
o-Tolualdehyde is $o-\text{CH}_3-\text{C}_6\text{H}_4-\text{CHO}$, which contains one $-\text{CHO}$ group.
Phthaldehyde is benzene-1,2-dicarbaldehyde, $\text{C}_6\text{H}_4(\text{CHO})_2$, which contains two $-\text{CHO}$ groups.
Butyraldehyde is $\text{CH}_3-\text{CH}_2-\text{CH}_2-\text{CHO}$, which contains one $-\text{CHO}$ group.
Therefore, phthaldehyde contains two $-\text{CHO}$ groups.
Answer: Phthaldehyde
Hence, the correct answer is option: 'C'.