Q48 / 150 · MHT CET 2026 (19 April Shift 2) · Chemistry
Which among the following is an aromatic aldehyde ?
- A
- B
- C
- Correct answerD
Solution
An aromatic aldehyde is a compound in which the aldehyde group ($\text{-CHO}$) is directly attached to an aromatic ring.
Let us evaluate the given options:
1. In the first structure (3-phenylpropanal), the $\text{-CHO}$ group is attached to an $sp^3$ hybridized carbon of an aliphatic chain, not directly to the benzene ring.
2. In the second structure (cinnamaldehyde), the $\text{-CHO}$ group is attached to an $sp^2$ hybridized carbon of an alkene chain.
3. In the third structure (cyclohexanecarbaldehyde), the $\text{-CHO}$ group is attached to a cyclohexane ring, which is non-aromatic.
4. In the fourth structure (2-methylbenzaldehyde or $o$-tolualdehyde), the $\text{-CHO}$ group is directly attached to the aromatic benzene ring.
Therefore, 2-methylbenzaldehyde is the only aromatic aldehyde among the given choices.
Let us evaluate the given options:
1. In the first structure (3-phenylpropanal), the $\text{-CHO}$ group is attached to an $sp^3$ hybridized carbon of an aliphatic chain, not directly to the benzene ring.
2. In the second structure (cinnamaldehyde), the $\text{-CHO}$ group is attached to an $sp^2$ hybridized carbon of an alkene chain.
3. In the third structure (cyclohexanecarbaldehyde), the $\text{-CHO}$ group is attached to a cyclohexane ring, which is non-aromatic.
4. In the fourth structure (2-methylbenzaldehyde or $o$-tolualdehyde), the $\text{-CHO}$ group is directly attached to the aromatic benzene ring.
Therefore, 2-methylbenzaldehyde is the only aromatic aldehyde among the given choices.
Hence, the correct answer is option: 'D'.