SN1 Mechanism for Tertiary Haloalkane

Steps:

• Tertiary bromoalkane (R₃C-Br) reacts via SN1 with aqueous NaOH due to steric bulk favoring unimolecular dissociation.
• Rate-determining step: heterolytic cleavage of C-Br bond, forming R₃C⁺ carbocation and Br⁻.
• Pathway diagram shows X as initial state or transition to carbocation, Y as the carbocation intermediate.
• OH⁻ then attacks Y to yield R₃C-OH product.

Why C is correct:

• In SN1, Y is the planar R₃C⁺ intermediate after Br⁻ departure, per the mechanism's two-step ionization.

Why the others are wrong:

• A: X precedes carbocation formation, representing reactant or early transition state.
• B: [HO-C-Br]⁻ suggests SN2-like attack, impossible for tertiary due to backside hindrance.
• D: Y cannot be [HO-C-Br]⁻, as SN1 forms free carbocation, not bridged anion.

Final answer: C