Question

When a chiral [S]-alcohol is reacted with $SOC{l}_2$ in presence of solvent like pyridine, chlorination happens, Predict the configuration and mechanism of product.

• A. R, $S_{N}i$
• B. R, $S_{N}2$
• C. R, $S_{N}1$
• D. S, $S_{N}i$

Answer 1

The correct option is B R, $S_{N}2$

In $S_{N}i$ reaction, when a chiral alcohol is reacted with $SOC{l}_2$, chlorination happens with retention of configuration. It takes place when no other solvent like pyridine is present.
But when external agent(base) is added, there is an inversion in the product because it then follows $S_{N}2$ mechanism.