Question: What two alkenes give rise to each alcohol as the major product of acid-catalyzed hydration?

The dehydration of analcohol in the presence of strong acids results in the formation of an alkene.

In the first step, oxygen abstracts protons and leaves as the hydronium ions to form a carbocation. In the last step, protonation takes place to form an alkene.

a. The dehydration of 2-methylpentan-2-ol produces two alkenes that give rise to the same alcohol upon hydration.

The reaction is shown below:

Formation of alkene in a

b. The dehydration of 1-methylcyclohexanol produces two alkenes that give rise to the same alcohol upon hydration.

The reaction is shown below:

Formation of alkene in b

c. The dehydration of butan-2-ol produces two alkenes that give rise to the same alcohol upon hydration.

The reaction is shown below:

Formation of alkene in c