Question

The reaction
is fastest when $X$ is :

• A. $OCOR$
• B. $O{C}_2{H}_5$
• C. $N{H}_2$
• D. $Cl$

Answer 1

Answer: (D)

Best leaving group (poorest nucleophile) is $C{l}^{\ominus }$, thus fastest reaction is with $Cl$.