Aldehydes, Ketones and Carboxylic Acids

Chemistry · Class 12

Simulation · Chemistry · Class 12

Cut the C=C: ozonolysis and hot KMnO₄

"Cut the C=C: ozonolysis and hot KMnO₄" is a free, interactive Class 12 Chemistry simulation for NEET and JEE, built on the NCERT section "Preparing aldehydes and ketones" in Aldehydes, Ketones and Carboxylic Acids. An alkene cut at its C=C: ozonolysis (Zn/H₂O) caps each half with =O, while hot KMnO₄ takes aldehyde halves on to acids. NEET has asked about this idea 2 times in 10 years of papers. JEE Main asked 60 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).

From the lesson Preparing aldehydes and ketones in Aldehydes, Ketones and Carboxylic Acids. Change the values and watch what happens.

Cut the C=C: ozonolysis and hot KMnO₄Chemistry · Class 12

What it shows

NCERT §8.2.1; §8.7

An alkene cut at its C=C: ozonolysis (Zn/H₂O) caps each half with =O, while hot KMnO₄ takes aldehyde halves on to acids.

Controls

3 to try

  • Selectalkene (but-2-ene, 2-methylbut-2-ene, 2,3-dimethylbut-2-ene, cyclohexene, styrene)
  • ToggleO₃ then Zn/H₂O / hot KMnO₄
  • Readoutsfragments and their names

Try this

Find the alkene whose ozonolysis gives propanone only.

In NEET

10 years of papers

Asked 2 times in 10 years of NEET.

See the past questions: Hydrocarbons (Alkenes), Aldehydes, Ketones and Carboxylic Acids (chapter)

In JEE Main

42 shifts analysed

60 questions from Aldehydes, Ketones and Carboxylic Acids across the 42 JEE Main shifts Lumi has analysed (2017–2026).

See the past questions

The idea behind it

NCERT §8.2.1–8.2.2

  • Oxidising alcohols: primary alcohols give aldehydes and secondary alcohols give ketones (Unit 7).
  • Dehydrogenating alcohols: vapour of a volatile alcohol is passed over heated Ag or Cu. This industrial route turns 1° alcohols into aldehydes and 2° alcohols into ketones.
  • Ozonolysis: an alkene treated with ozone and then zinc dust and water splits at the C=C to give aldehydes, ketones or both, depending on the groups around the double bond.
  • Hydration of alkynes: water adds to ethyne in the presence of H₂SO₄ and HgSO₄ to give acetaldehyde. Every other alkyne gives a ketone this way.
  • Rosenmund reduction: an acyl chloride is hydrogenated over palladium on barium sulphate, and the reaction stops at the aldehyde.
  • Stephen reaction: a nitrile is reduced by stannous chloride and hydrochloric acid to an imine, and hydrolysing the imine gives the aldehyde.
  • DIBAL-H, diisobutylaluminium hydride, reduces nitriles selectively to imines, which hydrolyse to aldehydes. Esters are also reduced to aldehydes by DIBAL-H.
  • Worked reagents: hexan-1-ol → hexanal with PCC; cyclohexanol → cyclohexanone with anhydrous CrO₃; ethanenitrile → ethanal with DIBAL-H; allyl alcohol → propenal with PCC; but-2-ene → ethanal with O₃ then H₂O–Zn dust.

Questions

4 answers

What does the "Cut the C=C: ozonolysis and hot KMnO₄" simulation show?
An alkene cut at its C=C: ozonolysis (Zn/H₂O) caps each half with =O, while hot KMnO₄ takes aldehyde halves on to acids.
Has NEET asked about this idea?
Yes. NEET has asked about this idea 2 times in 10 years of papers.
Does JEE Main ask questions from Aldehydes, Ketones and Carboxylic Acids?
Yes. JEE Main asked 60 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
Is this simulation free?
Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Preparing aldehydes and ketones" in Aldehydes, Ketones and Carboxylic Acids (Class 12 Chemistry).

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