Question

Benzamide on reaction with \[POC{l_3}\] gives
(A) Aniline
(B) Chlorobenzene
(C) Benzylamine
(D) Benzonitrile

Answer 1

Hint: The chemical name of \[POC{l_3}\] is phosphoryl chloride. It is used as a dehydrating agent in the given reaction.

Complete Step by Step Solution:
Phosphoryl chloride is a colourless liquid with the formula \[POC{l_3}\]. It hydrolyses in moist air and releases phosphoric acid and fumes of hydrogen chloride. Phosphoryl chloride 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 \[{C_6}{H_5}CON{H_2}\]. It is the simplest amide derived from benzoic acid. It is soluble in organic solvents and water. These are organic compounds which contain a carboxamide substituent which is attached to a benzene ring. Benzamide is an extremely weak basic compound.

When benzamide reacts with \[POC{l_3}\], a dehydration reaction takes place. The term dehydration means that \[{H_2}O\] is lost from the compound, which results in the formation of the main product that is benzonitrile. Benzonitrile is used as an intermediate for rubber manufacturing, chemicals and as a solvent for nitrile rubber.

The reaction of conversion of benzamide on treatment with \[POC{l_3}\] to give benzonitrile is given below:

Image: Conversion of benzamide to benzonitrile

So, we can say that Benzonitrile is formed when benzamide reacts with \[POC{l_3}\].

Note: \[POC{l_3}\]is also known as phosphorous oxychloride. Phosphorus oxychloride is synthesised industrially by reacting phosphorus trichloride and oxygen atoms. It can also be prepared by reacting phosphorous trichloride with phosphorus pentachloride. It does not dissolve in water as it forms hydrogen chloride and phosphoric acid by reacting with water.