Organic conversion

But-2-ene to ethanal

1 step: ozonolysis

Class 11, Chapter 9 Hydrocarbons

Alternative routes (4)

But-2-ene → Ethanoic acid → Ethanol → Ethanal
1. But-2-ene to ethanoic acid: hot acidified KMnO₄.
2. Ethanoic acid to ethanol: (i) LiAlH₄ (ii) H₃O⁺.
3. Ethanol to ethanal: PCC.
But-2-ene → Ethanoic acid → Ethanoyl chloride → Ethanal
1. But-2-ene to ethanoic acid: hot acidified KMnO₄.
2. Ethanoic acid to ethanoyl chloride: SOCl₂.
3. Ethanoyl chloride to ethanal: H₂, Pd/BaSO₄.
But-2-ene → Ethanoic acid → Ethyl ethanoate → Ethanal
1. But-2-ene to ethanoic acid: hot acidified KMnO₄.
2. Ethanoic acid to ethyl ethanoate: CH₃CH₂OH, conc. H₂SO₄ (catalyst), heat.
3. Ethyl ethanoate to ethanal: (i) DIBAL-H (ii) H₂O.
But-2-ene → Ethanoic acid → Ethanamide → Ethanenitrile → Ethanal
1. But-2-ene to ethanoic acid: hot acidified KMnO₄.
2. Ethanoic acid to ethanamide: NH₃, then heat.
3. Ethanamide to ethanenitrile: P₂O₅, heat.
4. Ethanenitrile to ethanal: (i) SnCl₂ + HCl (ii) H₃O⁺.

Why these reagents

Reagent and reason, step by step

Step 1: But-2-ene to ethanal: (i) O₃ (ii) Zn, H₂O Ozonolysis splits the double bond into two molecules of ethanal.

Questions

How many steps does it take to convert but-2-ene to ethanal?

1 step: But-2-ene, then ethanal.

Which named reaction is used to convert but-2-ene to ethanal?

Ozonolysis. Ozone adds to an alkene to form an ozonide, which is cleaved by zinc and water to give aldehydes or ketones.

What is the reagent for step 1 of but-2-ene to ethanal?

But-2-ene to ethanal: (i) O₃ (ii) Zn, H₂O. Ozonolysis splits the double bond into two molecules of ethanal.