The reaction of ${\text{(CH}}_3{)}_3{\text{COCH}}_3$ with concentrated $\text{HI}$ at room temperature yields which of the following?

Solution

1. The ether oxygen is protonated by $\text{HI}$ to form an oxonium ion.
2. The bond between the tertiary carbon and oxygen breaks to form a stable tert-butyl carbocation.
3. The iodide ion attacks the tert-butyl carbocation to form tert-butyl iodide.
4. The methanol remains as the other product.
5. Hence the answer is (B).