Question

How many structures of F are possible?

• A. $6$
• B. $3$
• C. $2$
• D. $5$

Answer 1

Answer: (B)

$3$ isomers of compound F are possible. They are shown above. Protonation in acidic conditions of the hydroxyl group of secondary alcohols converts the hydroxyl group into a leaving group, which departs as water.

The carbocation intermediate can rearrange and it will then be deprotonated in a $E_1$ elimination mechanism. This is the reverse of acid-catalyzed hydration of alkenes.

Hence, the correct option is $D$