Simulation · Chemistry · Class 12
The oxidation ladder
From the lesson Preparing aldehydes and ketones in Aldehydes, Ketones and Carboxylic Acids. Change the values and watch what happens.
The oxidation ladderChemistry · Class 12
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.