Question

Which of the following ${S_N}^2$ reactions is the fastest?

• A. $C{H}_{3}C{H}_{2}C{H}_{3}Br+H{O}^{-}\to C{H}_{3}C{H}_{2}C{H}_{3}OH+B{r}^{-}$
• B. $C{H}_{3}C{H}_{2}C{H}_{2}Cl+H{O}^{-}\to C{H}_{3}C{H}_{2}C{H}_{3}OH+C{l}^{-}$
• C. $C{H}_{3}C{H}_{2}C{H}_{2}I+H{O}^{-}\to C{H}_{3}C{H}_{2}C{H}_{3}OH+I^{-}$
• D. $C{H}_3\underset{F}{\underset{|}{C}}HC{H}_3+H{O}^{-}\to C{H}_3\underset{OH}{\underset{|}{C}}HC{H}_3+F^{-}$

Answer 1

The correct option is C $C{H}_{3}C{H}_{2}C{H}_{2}I+H{O}^{-}\to C{H}_{3}C{H}_{2}C{H}_{3}OH+I^{-}$

A standard $s_N^2$ reaction can be shon $a$.

It is clear that, more the tendancy of $x$ to leave the carbon,

mere faster the reaction olll occur.

For halogens, learing group order: $[I>Br>cl>F$

nence alkyl group having 'I' as leaving group attached sill

be fastest.

so, option C is correct.