Question

Which of the following compounds will most readily be dehydrated to give alkene under acidic condition?

• A. 2-Hydroxycyclopentanone
• B. 3-Hydroxypentan-2-one
• C. 1-Pentanol
• D. 4-Hydroxypentan-2-one

Answer 1

Answer: (D)

3-Hydroxypentan-2-one and 4-Hydroxypentan-2-one will most readily be dehydrated to give alkene under acidic condition. This will lead to formation of $\alpha -\beta$ unsaturated ketone. But out of both 4-Hydroxypentan-2-one will most readily be dehydrate to give alkene under acidic condition.
Note: Dehydration of 2-Hydroxycyclopentanone will lead to $C=C$ double bond in 5 member ring that will cause strain and product is less likely to be formed.