SN1 with a tertiary substrate
A chiral tertiary alkyl bromide is dissolved in water and ethanol, with no strong base present. Substitution occurs mainly by which mechanism, with what stereochemical result?
Answer C: explanation for every choice
A
Tertiary carbons are too hindered for backside SN2 attack.
B
SN2 inverts configuration and isn't feasible at a tertiary carbon.
C
Correct. Tertiary carbocations are stabilized, and polar protic solvents favor ionization. The nucleophile can attack either face of the planar carbocation.
D
E2 requires a strong base. Some E1 may occur, but substitution is the question.
TakeawayTertiary + polar protic solvent + weak nucleophile → SN1 → racemization.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID cp142.