Q.11-50d - Organic Chemistry (Mcmurry)

Question

Question: What products would you expect from the reaction of 1-bromopropane with each of the following? 

(d) NaCN

Step-by-Step Solution

Answer

Answer:

$$\begin{gathered} {\text{CH}}_3{\text{CH}}_2{\text{CH}}_2{\text{Br+NaCN→CH}}_3{\text{CH}}_2{\text{CH}}_2\text{CN+NaBr} \\ \text{ Substitution reaction } \end{gathered}$$

Step1: S N 2 reaction

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

Two reacting species are involved in the rate-determining steps. 

Step2: Reaction of CH 3 CH 2 CH 2 Br+NaCN

It is a substitution reaction in which C-Br is broken and the C-CN bond is formed in a single-step process which means the bromide ion is substituted by the cyanide ion. Hence, it is a substitution reaction, and bromide and cyanide are nucleophiles’ so-called nucleophilic substitution reactions. 

 

$$\begin{gathered} {\text{CH}}_3{\text{CH}}_2{\text{CH}}_2{\text{Br+NaCN→CH}}_3{\text{CH}}_2{\text{CH}}_2\text{CN+NaBr} \\ \text{ Substitution reaction } \end{gathered}$$