What is the common name of the given compound?

The correct answer is Option (1) → β-Bromobutyraldehyde

In common names the carbons of the chain are marked with Greek letters, starting from the carbon next to the –CHO group. The compound is \( \ce{CH3-CHBr-CH2-CHO} \).

• Parent: four carbons with a –CHO group, \( \ce{CH3CH2CH2CHO} \), is butyraldehyde (from butyric acid).

• α-carbon: the \( \ce{CH2} \) directly linked to the –CHO group.

• β-carbon: the next carbon, the CH that carries Br.

• γ-carbon: the end \( \ce{CH3} \) group.

Br is on the β-carbon, so the name is β-bromobutyraldehyde.

NCERT (2026-27 edition):
(a) Common names – “… The common names of most aldehydes are derived from the common names of the corresponding carboxylic acids … by replacing the ending –ic of acid with aldehyde. … The location of the substituent in the carbon chain is indicated by Greek letters α, β, γ, δ, etc. The α-carbon being the one directly linked to the aldehyde group, β- carbon the next, and so on.”