Question

How do you make Aldehyde from Carboxylic acid?

Answer 1

Aldehyde:

• Aldehyde is an organic compound that has $-\mathrm{CHO}$ carbonyl group.
• In $-\mathrm{CHO}$ carbonyl group, the Carbon atom shares a double bond with an Oxygen atom, a single bond with a Hydrogen atom, and a single bond with another atom or group of atoms where the functional group gets attached.

Carboxylic acid:

• Carboxylic acid is an organic compound that has$-\mathrm{COOH}$ group.
• The Carboxylic acid has extra Oxygen compared to the Aldehyde.
• In $-\mathrm{COOH}$ Carboxyl group, the Carbon atom shares a double bond with an Oxygen atom, a single bond with a Hydroxyl group$\left(\mathrm{OH}\right)$, and a single bond with other atoms or groups of atoms where the functional group gets attached.

To make Aldehyde from Carboxylic acid:

• To obtain Aldehyde from the Carboxylic acid, we have to treat it with a reducing agent.
• The reducing agent which is used in the conversion of the acid into aldehyde is ${\mathrm{LiAlH}}_4$ or ${\mathrm{NaBH}}_4$
• Reduce the acid to primary alcohol and further partially oxidize that alcohol back to the aldehyde using the $\mathrm{PCC}$ (Pyridinium chlorochromate).

Therefore, to prepare Aldehyde from Carboxylic acid, reduce the acid to primary alcohol and further partially oxidize that Alcohol back to the Aldehyde using the Pyridinium chlorochromate.