Question

Show how you would convert the following starting materials to the indicated nitriles:

$\mathbf{\left(}\mathbf{a}\mathbf{\right)}\mathbf{phenylaceticacidphenylacetonitrile}$

$\mathbf{\left(}\mathbf{b}\mathbf{\right)}\mathbf{phenylaceticacid}\to \mathbf{3}\text{-}\mathbf{phenylpropionitrile}$

$\mathbf{\left(}\mathbf{c}\mathbf{\right)}\mathbf{p}\mathbf{-}\mathbf{chloronitrobenzenep}\mathbf{-}\mathbf{chlorobenzonitrile}$

Short answer

Conversion of phenylacetonitrile from phenylacetic acid (a) is given below:

Conversion of 3-phenylpropionitrile from phenylacetic acid (b) is given below:

Conversion of p-chlorobenzonitrile from p-chloronitrobenzene (c) is given below:

Step-by-step solution

Step-by-Step SolutionStep 1: Role of POCI3

${\text{POCl}}_{\text{3}}$is a commonly used dehydrating agent in the chemical laboratories. It is used as a dehydrating agent in the preparation of nitriles from primary amides.

Synthesis of phenylacetonitrile (a) from phenylacetic acid

When phenylacetic acid reacts with$\mathbf{\left(}{\mathbf{SOCI}}_2\mathbf{\right)}$then there is a formation of acetyl chloride, in the next step acetyl chloride react with ammonia then there is a formation of amide, In the last step amide react with then there is a formation of phenylacetonitrile.

Synthesis of phenylacetonitrile

Step 3: Synthesis of 3-phenylpropionitrile (b) from phenylacetic acid

When phenylacetic acid reacts with strong reducing reagent like lithium aluminium hydride, then 2-phenylethanol is formed. Which on further reacting with TsCl, pyridine and NaCN , forms 3-phenylpropionitrile.

The reaction is as follows:

Synthesis of 3-phenylpropionitrile

Conversion of p-chlorobenzonitrile from p-chloronitrobenzene

When p-chloronitrobenzene is reacted with Fe/HCl, reduction of nitro group takes place in the amine and there is a formation of p-chloroaniline. In the next step, p-chloroaniline reacts with ${\mathbf{NaNO}}_2\mathbf{}\mathbf{HCl}$and there is a formation of diazonium salts, In the last step diazonium salts react with CuCN and there is a formation of p-chlorobenzonitrile.

The reaction is as follows:

Synthesis of p-chlorobenzonitrile