PrepRung
Sign inSign up free

JEE Main 2019 · Chemistry · Carbonyl Compounds, Carboxylic Acids and Amines · medium

Acetaldehyde and propanal are mixed in the presence of dilute NaOH. Considering only constitutional (structural) isomers and ignoring stereoisomers…

Single correct option

Acetaldehyde and propanal are mixed in the presence of dilute NaOH. Considering only constitutional (structural) isomers and ignoring stereoisomers, the number of different aldol (β-hydroxy aldehyde) addition products that can form is
  1. A. 2
  2. B. 3
  3. C. 6
  4. D. 4
Show answer and solution

Answer: (D) 4

Both aldehydes have α\alpha-hydrogens, so each can act as enolate or electrophile. Self-aldol of ethanal: 3-hydroxybutanal; self-aldol of propanal: 3-hydroxy-2-methylpentanal. Cross-aldol: ethanal enolate + propanal gives 3-hydroxypentanal; propanal enolate + ethanal gives 3-hydroxy-2-methylbutanal. Total 2+2=42+2=4. Stereoisomers from the new chiral centres are not counted.
Report a mistake

Original question written in the JEE Main 2019 pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake