Question

PCC cannot oxidize aldehydes to carboxylic acids because:

• A. It is a weak oxidant
• B. Oxidation by PCC is carried in non-aqueous solvent $\left(C{H}_{2}C{l}_2\right)$ in which aldehyde cannot exist as a gem-diol
• C. PCC does not dissolve in solvent $\left(C{H}_{2}C{l}_2\right)$ in the presence of aldehyde
• D. PCC decomposes upon formation of aldehyde and thus loses its oxidizing power

Answer 1

The correct option is B Oxidation by PCC is carried in non-aqueous solvent $\left(C{H}_{2}C{l}_2\right)$ in which aldehyde cannot exist as a gem-diol

In order for an aldehyde to oxidize to a carboxylic acid, it must first form a hydrate.
The formation of a hydrate is not possible in a non-aqueous medium, and thus further oxidation to carboxylic acid is restricted.