What is the most likely mechanism for the reaction of 2-bromo-2-methylpropane with hydroxide ion to form 2-methyl-2-propanol?

• A. SN1 mechanism
• B. E2 mechanism
• C. SN2 mechanism
• D. E1 mechanism

Answer: (A)

Verified step by step guidance

1. Identify the structure of the substrate: 2-bromo-2-methylpropane is a tertiary alkyl halide because the carbon bonded to the bromine is connected to three other carbons.
2. Recall that tertiary alkyl halides typically favor the SN1 mechanism due to steric hindrance, which makes backside attack (required for SN2) difficult.
3. Consider the nature of the nucleophile: hydroxide ion (OH⁻) is a strong nucleophile and a strong base, but in the case of a tertiary substrate, the reaction pathway is often determined more by the substrate's structure than the nucleophile strength.
4. Understand the SN1 mechanism involves two steps: first, the leaving group (Br⁻) departs, forming a carbocation intermediate; second, the nucleophile (OH⁻) attacks the carbocation to form the alcohol.
5. Evaluate other mechanisms: E2 requires a strong base and a good leaving group with a suitable β-hydrogen, but here the formation of a stable carbocation favors SN1; SN2 is unlikely due to steric hindrance; E1 is possible but less favored with a strong nucleophile like OH⁻.