Alcohol Reactions: Aldehyde/Ketone formation from Diols using Sodium Periodate (NaIO4)

Vicinal diols can react with sodium periodate (NaIO4) in an aqueous environment to cleave the bond between the two alcohol groups and form 2 ketone/aldehyde products:

If the diol is part of a ring structure, the ring is broken and the two ends of the molecule will contain the respective ketone/aldehyde products:

Ring Cleavage Reaction Example

The reaction mechanism is depicted below:

Mechanism

In the first step, one of the alcohol groups has the free electrons react with the iodine core of the NaIO4 molecule, forming an O-I bond.

In the second step, the other alcohol group has the free electrons react with the iodine core of the NaIO4 molecule, forming another O-I bond. The resulting molecule now has a ring structure formed with the IO3 molecule after one of the O atoms has left the IO4 molecule.

In the third step, the IO3 molecule breaks apart from the reactant, with the bond between the alcohol groups breaking causing the molecules cleavage. In this example, a reactant with an existing ring structure was used, so the result is 1 molecule with two aldehyde functional groups on either end of the molecule. If a non-ring structure had been used, there would be two resulting aldehyde molecules (or ketone if the carbon atoms were more substituted).

The NaIO4 reaction is commonly used after treating an alkene with osmium tetroxide (OsO4), which produces vicinal diols from an alkene bond.

Practice this reaction using our Reaction Solver!