Q 11-11-41 E-c - Organic Chemistry (Mcmurry)

Question

Which compound in each of the following pairs will react faster in an S_N2 reaction with OH^- ?

(c) ${\left({\mathrm{CH}}_3\right)}_3\mathrm{CCl} \mathrm{or} {\mathrm{CH}}_3\mathrm{Cl}$

Step-by-Step Solution

Answer

CH₃Cl

S N 2 reaction

It is a nucleophilic substitution reaction in which an old bond is broken, and new bond is formed. Both processes co-occur. Hence, it’s a single-step reaction.

The two reacting species are involved in the rate determining steps.

Nucleophile

Nucleophiles are the negatively charged ions or the neutral species having the lone pair of electrons ready for bonding.

Species react faster with OH -

If the species is a better leaving group, then it reacts faster with the nucleophile. 

Cl is a better leaving group but ${\left({\mathrm{CH}}_3\right)}_3$ is a very bulky group, so it cannot show nucleophilic substitution easily compared to CH₃ which a lighter group and the best is leaving group.

CH₃Cl show fast reaction than ${\left({\mathrm{CH}}_3\right)}_3\mathrm{Cl}$