Pinacol Pinacolone rearrangement

reaction mechanism

pinacol pinacolone rearrangement

Reaction...

in this reaction we discuss about the pinacol pinacolone rearrangement.
conversion of pinacol into pinacolone taking place in the presence of mineral acid ,acid chloride,or other electrophillic reagents is known as the pinacol pinacolone rearrangement.

It is an example of 1,2 shift intramolecular rearrangement.

Mean

in this reaction pinacol show a product pinacolone in the presence of acid and at high temperature.

Mechanism.

Step1- A proton is added to one of the hydroxyl groups..

mean firstly oxygen lone pair attract the H positive ion and formation of oxonium ion.

step2- The protonated hydroxyl group is lost as water to form carbonium ion.
next these show resonance stabilized carbonium ion.

step3- The migrating group methyl group with it's pair of electrons migrates.

step4- A proton is lost to form the product, pinacolone.

This rearrangement take place in the presence of sulphuric acid and at high temperature.

conversion of oxonium ion to carbonium ion is the rate determining step.

The migration of the alkyl and elimination of OH by the proton take place simultaneously
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