Question

Nitriles, $\mathbf{R}\mathbf{-}\mathbf{C}\equiv \mathbf{N}$, undergo a hydrolysis reaction when heated withaqueous acid. What is the structure of the compound produced by hydrolysis of propanenitrile, ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{C}\equiv \mathbf{N}$, if it has IR absorptions from$\mathbf{2500}\mathbf{-}\mathbf{3100}{\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$ and at $\mathbf{1710}{\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$, and has ${\mathbf{M}}^{\mathbf{+}}\mathbf{=}\mathbf{74}$?

Short answer

The N-H functional group of amine can be easily detected using the IR spectroscopy.It shows a characteristic absorption in the range 3300 to 3500 cm^-1. An N-H absorption band is less intense in comparison to the O-H absorption band.

Step-by-step solution

IR spectroscopy

The N-H functional group of amine can be easily detected using the IR spectroscopy.It shows a characteristic absorption in the range 3300 to 3500 cm^-1. An N-H absorption band is less intense in comparison to the O-H absorption band.

Structure of the compound from the given data

The m/z value of the product is 74. The IR spectrum shows that the compound has IR absorptions at the values ${\text{2500 - 3100 cm}}^{\text{- 1}}$and at ${\text{1710 cm}}^{\text{- 1}}$.

When the nitrile undergoes hydrolysis forms carboxylic acid. The given propane nitrile,${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{C}\equiv \text{N}$undergoes hydrolysis to give propionic acid.

IR absorptions at the values from ${\text{2500 - 3100 cm}}^{\text{- 1}}$indicates the hydroxyl group at the carboxylic acid. The value at ${\text{1710 cm}}^{\text{- 1}}$indicates the carbonyl group of the carboxylic acid functional group.

Reaction of nitrile with${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$and heat

The molecular weight of the compound matches with the expected compound. The structure of the compound can be given as: