Question

Consider the compounds (I) R-I (II) R-Br ; (III) R-Cl ; (IV)R-F . The rate of $S_{N}2$ reaction is:

• A. I>II>III>IV
• B. II>I>III>IV
• C. I=II=III=IV
• D. IV>III>II>I

Answer 1

The correct option is A I>II>III>IV

$S{N}_2$ reaction,nucteophilic attack from back side.The rate of $S{N}_2$

reaction depend on the learning group. Rate of reaction increases with good leading group.the order of leading group is $I^{-}>B{r}^{-}>C{l}^{-}>F^{-}$

So rate increases as

$R-I>R-Br>R-Cl>R-F$