What is the common name of the given compound?

Cinnamaldehyde

The correct answer is Option (4) → Cinnamaldehyde

The given compound contains:

• A benzene ring
• An α,β-unsaturated aldehyde group (–CH=CH–CHO) attached to the ring.

Thus the structure is:

C₆H₅–CH=CH–CHO

This compound is commonly known as cinnamaldehyde, which is the major component of cinnamon oil.

The IUPAC name of cinnamaldehyde is 3-phenylprop-2-enal.

Option-wise Explanation

Option 1: Phthaldehyde

Incorrect. Phthaldehyde contains two –CHO groups on the benzene ring.

Option 2: Salicylaldehyde

Incorrect. Salicylaldehyde has a –CHO and –OH group attached directly to the benzene ring.

Option 3: Vanillin

Incorrect. Vanillin contains –CHO, –OCH₃, and –OH groups on the benzene ring.

Option 4: Cinnamaldehyde

Correct. The compound C₆H₅–CH=CH–CHO is cinnamaldehyde.