SN1 Mechanism Intermediate Identification

Steps:

• Tertiary bromoalkane favors SN1 with aqueous NaOH due to stable tertiary carbocation formation.
• Rate-determining step: heterolytic cleavage of C-Br bond, producing R₃C⁺ intermediate and Br⁻.
• Energy diagram shows initial transition state (X), then carbocation minimum (Y).
• Nucleophile OH⁻ then attacks Y to form R₃C-OH.

Why C is correct:

• Y corresponds to the carbocation (C⁺) intermediate, the energy minimum after Br⁻ departure in SN1 pathway.

Why the others are wrong:

• A: X is the transition state for ionization, not the stable C⁺.
• B: HO-C-Br represents no known SN1 species; it's not formed.
• D: Y is the carbocation, not the protonated alcohol-like HO-C-Br.

Final answer: C