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Oxidation of primary alcohols to carboxylic acids

Description: Primary alcohols treated with chromic acid will be converted to carboxylic acids.

Notes: There are many other ways to show this transformation that amount to the same thing. Such as

  • K2Cr2O7 / H3O(+)
  • Na2Cr2O7/H3O(+)
  • CrO3/H2SO4
  • KCrO4/H3O(+)

All of these conditions generate H2CrO4 in the flask.

KMnO4 will also do the same reaction.


Notes: Note the different reaction conditions here that do the exact same reaction.

Mechanism:The mechanism is not generally considered important for the purposes of Org 1/ Org 2, but one is depicted here. It’s a long mechanism, and there are a huge number of different ways to to depict the different protonation and deprotonation events.

The key here is that Cr is a good leaving group on O, and a base can remove the adjacent proton and perform an elimination reaction. This has to happen twice: once on the primary alcohol, and again on the aldehyde hydrate.