Starting from a chiral substrate, SN1 typically yields which type of mixture?

Starting from a chiral substrate, SN1 typically yields which type of mixture?

• A. Racemization to a racemic mixture
• B. Pure enantiomer
• C. Meso compound
• D. Diastereomeric mixture

Answer: (A)

In SN1, the leaving group departs to give a planar carbocation. That flat intermediate has no preferential face for attack, so the nucleophile can approach from either side with equal probability. If the original substrate is chiral at the reactive carbon, this leads to both enantiomers in equal amounts—a racemic mixture. The rate-determining step is carbocation formation, so stereochemistry isn’t controlled during the fast nucleophilic attack. If other stereocenters exist, you could get diastereomeric relationships, but the center that lost the leaving group becomes racemic. This is why the typical outcome from a chiral SN1 reaction is racemization rather than a single enantiomer.

In SN1, the leaving group departs to give a planar carbocation. That flat intermediate has no preferential face for attack, so the nucleophile can approach from either side with equal probability. If the original substrate is chiral at the reactive carbon, this leads to both enantiomers in equal amounts—a racemic mixture. The rate-determining step is carbocation formation, so stereochemistry isn’t controlled during the fast nucleophilic attack. If other stereocenters exist, you could get diastereomeric relationships, but the center that lost the leaving group becomes racemic. This is why the typical outcome from a chiral SN1 reaction is racemization rather than a single enantiomer.