Question

In an $S_{N}1$ reaction on chiral centres, there is:

• A. $100$% retention
• B. $100$% inversion
• C. $100$% racemization
• D. Inversion more than retention leading to initial racemization

Answer 1

The correct option is D Inversion more than retention leading to initial racemization

In an $S_{N}1$ reaction on chiral centres, there is inversion more than retention leading to initial racemization.

Thus if we start with a pure enantiomer and carry out $S_{N}1$ substitution on chiral carbon, the product will be racemic. This is because a planar carbocation intermediate is obtained. The nucleophile can attack from either side of this intermediate.

Option D is correct.