Q57c - Organic Chemistry (Mcmurry)

Question

Question: Order each of the following sets of compounds with respect to reactivity:

c.   CH₃ CH₂ CH₂ OCH₃   CH₃ CH₂ CH₂OTs   CH₃ CH₂ CH₂ Br

Step-by-Step Solution

Answer

Answer

CH₃ CH₂ CH₂ OCH₃ <  CH₃ CH₂ CH₂ Br <  CH₃ CH₂ CH₂OTs 

Step 1: S N 2 reaction

It is a nucleophilic substitution reaction in which old bond is break and new bond is formed both the process occur simultaneously. Hence, it’s a single step reaction.

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

Step 2: Reactivity towards S N 2 reaction

As the reaction is single step reaction so, no intermediate is formed and S_N2  occur fast with primary alkane than secondary alkane.

S_N2  occur fast with those reacting species which have best leaving group  

OTs is one of the best leaving group then halogens are the good leaving group

So, 

CH₃ CH₂ CH₂ OCH₃ <  CH₃ CH₂ CH₂ Br <  CH₃ CH₂ CH₂OTs 

Reactivity order