0 votes
27 views
ago in Organic Chemistry by (570 points)
Identify and explain the mechanism behind a common rearrangement reaction that occurs with acidic dehydration of 2-methylcyclohexanol.

1 Answer

0 votes
ago by (210 points)
The common rearrangement reaction that occurs with acidic dehydration of 2-methylcyclohexanol is the Wagner-Meerwein rearrangement. This is a 1,2-alkyl shift that occurs during the formation of a more stable carbocation intermediate in the reaction pathway.The mechanism behind this rearrangement is as follows:1. Protonation: In the presence of a strong acid, such as sulfuric acid  H2SO4  or phosphoric acid  H3PO4 , the hydroxyl group  -OH  of 2-methylcyclohexanol gets protonated, forming a good leaving group  H2O .2. Formation of the initial carbocation: The bond between the carbon and the protonated hydroxyl group breaks, resulting in the departure of the water molecule and the formation of a secondary carbocation at the 2-position of the cyclohexane ring.3. Wagner-Meerwein rearrangement: The secondary carbocation formed in step 2 is less stable than a tertiary carbocation. To achieve greater stability, a 1,2-alkyl shift occurs, where a methyl group  along with its bonding electrons  migrates from the adjacent carbon to the carbocation center. This results in the formation of a more stable tertiary carbocation at the 1-position of the cyclohexane ring.4. Elimination: A base, which can be a solvent molecule or the conjugate base of the acid used, abstracts a proton from a carbon adjacent to the carbocation center. This leads to the formation of a double bond between the carbocation center and the adjacent carbon, resulting in the formation of the alkene product.In the case of 2-methylcyclohexanol, the major product of this reaction is 1-methylcyclohexene due to the more stable tertiary carbocation intermediate formed during the Wagner-Meerwein rearrangement.

Related questions

Welcome to Sarvan Science Q&A, where you can ask questions and receive answers from other members of the community.
...