Question:What reagents are needed to convert phenylacetonitrile (${\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{CN}$) to each compound:

$$\begin{gathered} \mathbf{a}\mathbf{.}\mathbf{}{\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{CO}\left({\mathrm{CH}}_3\right) \\ \mathbf{b}\mathbf{.}\mathbf{}{\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{COC}{\left({\mathrm{CH}}_3\right)}_{\mathbf{3}} \\ \mathbf{c}\mathbf{.}\mathbf{}{\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{CHO} \\ \mathbf{d}\mathbf{.}\mathbf{}{\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{COOH} \end{gathered}$$

Nitriles convert to ketones when treated with Grignard reagents. The reaction is a type of nucleophilic addition.

The structure of phenylacetonitrile is given below:

Phenylacetonitrile

The conversion of phenylacetonitrile to a and b using Grignard reagents is shown below:

(a${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2\mathrm{COC}{\left({\mathrm{CH}}_3\right)}_2$

Formation of${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2\mathrm{COC}{\left({\mathrm{CH}}_3\right)}_2$

(b)${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2\mathrm{COC}{\left({\mathrm{CH}}_3\right)}_2$

Formation of${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2\mathrm{COC}{\left({\mathrm{CH}}_3\right)}_2$

Nitriles can be reduced to aldehyde in presence of DIBAL-H.

The compound given in (c) is${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2\mathrm{CHO}$which you can produce from phenylacetonitrile using DIBAL-H. The reaction is given below:

Formation of${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2\mathrm{CHO}$

Nitriles convert to carboxylic acid in the presence of an acid.

The compound given in (d) is${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2\mathrm{COOH}$ which you can produce from phenylacetonitrile using ${\mathrm{H}}_3{\mathrm{O}}^{+}$. The reaction is given below:

Formation of${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2\mathrm{COOH}$