As `S_N2` reaction at an asymmetric carbon of a compound always gives:

Options

A. an enantiomer of the substrate
B. a product with opposite optical rotation
C. a mixture of diastereomers
D. a single stereoisomer

Answer

D

Explanation

In `S_(N^(2))` reaction, an optically active alkyl halide gives an optically active product. The product may not have opposite optical rotation to that of the alkyl halide as the two are not enantiomers. Therefore, a single stereoisomer is the product.