PCC (pyridinium chlorochromate) is an oxidizing reagent used primarily in organic chemistry to oxidize alcohols selectively. Its main function in a reaction is to oxidize:
- Primary alcohols to aldehydes
- Secondary alcohols to ketones
Unlike stronger oxidants such as chromic acid, PCC does not further oxidize aldehydes to carboxylic acids because it operates under anhydrous conditions, preventing the formation of aldehyde hydrates that would be susceptible to further oxidation
. How PCC works in the reaction:
- The oxygen atom of the alcohol attacks the chromium in PCC, forming a chromate ester intermediate.
- A base (often pyridine present in the reaction) then removes a proton from the carbon adjacent to the oxygen.
- This deprotonation leads to the formation of a carbonyl group (C=O), converting the alcohol into an aldehyde or ketone.
- During this process, chromium is reduced from Cr(VI) to Cr(IV)
Because PCC is used in non-aqueous solvents like dichloromethane, it avoids over-oxidation and allows for selective oxidation stopping at the aldehyde or ketone stage
. In summary, PCC acts as a mild, selective oxidant that converts primary and secondary alcohols into aldehydes and ketones, respectively, without further oxidation to carboxylic acids, making it valuable for controlled oxidation reactions in organic synthesis
