Question

Benzamide on treatment with ${\text{POC}}{{\text{l}}_{\text{3}}}$gives:
A. Aniline
B. Benzonitrile
C. Chlorobenzene
D. Benzyl amine

Answer 1

In the above question, it is asked what happened when benzamide is treated with ${\text{POC}}{{\text{l}}_{\text{3}}}$. Since, ${\text{POC}}{{\text{l}}_{\text{3}}}$ is a dehydrating agent, it dehydrates benzamide to form a cyanide.

Complete step-by-step answer: Phosphoryl chloride is a colourless liquid with the formula ${\text{POC}}{{\text{l}}_{\text{3}}}$. It hydrolyses in moist air and releases phosphoric acid and fumes of hydrogen chloride. POCl3 is a commonly used dehydrating agent in chemical laboratories. It is used as a dehydrating agent for the preparation of nitriles from primary amides.
Benzamide is a white solid with chemical formula ${{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{CON}}{{\text{H}}_{\text{2}}}$. It is the simplest amide derived from benzoic acid. It is soluble in organic solvents and water. These are organic compounds which contain a carboxamido substituent which is attached to a benzene ring. Benzamide is an extremely weak basic compound.
When benzamide reacts with ${\text{POC}}{{\text{l}}_{\text{3}}}$, dehydration reaction take place, which means ${{\text{H}}_{\text{2}}}{\text{O}}$ is lost from the compound which results in the formation of benzonitrile. Benzonitrile is used as an intermediate for rubber chemicals and as a solvent for nitrile rubber.
The reaction of conversion of benzamide on treatment with ${\text{POC}}{{\text{l}}_{\text{3}}}$ to give benzonitrile is given below:

So, we can say that Benzonitrile is formed when benzamide reacts with ${\text{POC}}{{\text{l}}_{\text{3}}}$.

Hence, the correct option is option B.

Note: Benzo nitriles react with amine to form N-substituted benzamide after hydrolysis.
Benzo nitriles ligands are readily displaced by stronger ligands making benzo nitriles complexes useful synthetic intermediates.
Nitrile-hydrolysing enzymes were generally unstable for commercial use in the isolated or purified state.