Question #0eadd

1 Answer
Nov 30, 2016

Here it is.


The pinacol rearrangement is the acid-catalyzed rearrangement of a 1,2-diol to a ketone.

The name of the rearrangement comes from the rearrangement of pinacol (2,3-dimethylbutane-1,2-diol) to pinacolone (2,2-dimethylbutanone).

There are several steps in the rearrangement.

Step 1. Protonation

The acid protonates an #"OH"# group, forming an oxonium ion.

Step 2. Loss of water

A molecule of water leaves, forming a 3° carbocation.

Step 3. 1,2-Methyl shift

A methyl group migrates to the carbocation, forming a resonance stabilized protonated carbonyl group.

Step 4. Deprotonation

A water molecule removes the proton from the carbonyl oxygen, forming the product, pinacolone.