Aldehydes And Ketones

(i) Etard Reaction:
- In this reaction, an aromatic hydrocarbon containing a group is oxidized to an aldehyde.
- Chromyl chloride (CrO Cl ) is used as the oxidizing agent.
Example: Toluene is converted to benzaldehyde.

(ii) Gattermann–Koch Reaction:
- This reaction is used for formylation of aromatic rings (introduction of group).
- Benzene reacts with CO and HCl in the presence of AlCl and CuCl as catalysts to give benzaldehyde.

(iii) Cannizzaro’s Reaction:
- Aldehydes without -hydrogen undergo self-oxidation and reduction in the presence of concentrated alkali.
- One molecule is reduced to alcohol and the other is oxidized to carboxylate salt.

(iv) Aldol Condensation:
- Aldehydes or ketones containing -hydrogen undergo condensation in the presence of dilute alkali to form -hydroxy aldehydes or ketones.
- On heating, these give -unsaturated carbonyl compounds.

Conclusion:
- Etard → toluene benzaldehyde.
- Gattermann–Koch → benzene benzaldehyde.
- Cannizzaro → aldehyde without -H alcohol + salt.
- Aldol → aldehyde/ketone with -H -unsaturated compound.

(i) 4-hydroxy-4-methylpentan-2-one from propanone:

To obtain 4-hydroxy-4-methylpentan-2-one from propanone, perform the following reaction:

(ii) 3-hydroxybutanol from ethanol:

To obtain 3-hydroxybutanol from ethanol, follow the reaction below:

(iii) Butanoic acid from butanal:

To obtain butanoic acid from butanal, follow this oxidation reaction:

(iv) Ethanoic anhydride from ethanoic acid:

To obtain ethanoic anhydride from ethanoic acid, use the following reaction:

(v) Phenyl ethanoic acid from benzyl alcohol:

To obtain phenyl ethanoic acid from benzyl alcohol, perform the reaction shown below: