The hydride ion affinity (HIA) is a measure of carbocation stability. The difference in HIA for a secondary allylic carbocation and a tertiary allylic carbocation is 12 kcal/mol. Assuming that this is also the difference in the energies of the transition state for the carbocation formations at 298 K, how much faster is the formation of the tertiary allylic carbocation compared to that of the secondary allylic carbocation?

• A. The formation of the tertiary allylic carbocation is 12 times faster than the formation of the secondary allylic carbocation.
• B. The formation of the tertiary allylic carbocation is 6.3×10⁹ times faster than the formation of the secondary allylic carbocation.
• C. The formation of the secondary allylic carbocation is 12 times faster than the formation of the tertiary allylic carbocation.
• D. The formation of the secondary allylic carbocation is 6.3×10⁹ times faster than the formation of the tertiary allylic carbocation.

Answer: (B)