Amide Hydrolysis

What is an Amide?

An amide is a functional group in which a carbonyl group is linked with the nitrogen atom by a single bond.

Amide is also known as derivatives of carboxylic acids having an OH group of COOH replaced by an NH2, NHR, NR2 of an amine.

What is Hydrolysis?

Hydrolysis is a chemical reaction of the interaction of chemicals with water, leading to the decomposition of both the substance and water.

Table of Content

Hydrolysis of Amide

Amide resists hydrolysis; even after prolonged heating, amide does not interact with water molecules to decompose. However, hydrolysis of amide is not impossible. It interacts with water molecules either in an acidic or a basic medium.

In an acidic medium, amide interacts with the water molecule to give a carboxylic acid and the salt of ammonia or amine salt.

In a basic medium, amide interacts with the water molecule to give a carboxylic acid and the salt of ammonia or amine salt.

  • In the human body, amide hydrolysis is catalysed by enzymes.

Types of Amide Hydrolysis

Amide interacts with a water molecule in two possible ways i.e.

  • Acid Catalysed Amide Hydrolysis
  • Base Catalysed Amide Hydrolysis

Acid Catalysed Amide Hydrolysis

In an acidic medium, amide interacts with the water molecule to give a carboxylic acid and the salt of ammonia or amine salt.

Mechanism:

Step 1: Protonation of amide carbonyl

We will activate the amide since we only have a weak nucleophile and a poor electrophile.

Protonation of the amide carbonyl makes it more electrophilic.

Step 2: Nucleophilic Addition

Lone pairs of oxygen would attack the carbonyl group; the electron would move towards oxonium ion, forming a tetrahedral intermediate.

Step 3: Proton transfer

Oxygen loses a proton to neutralise the charge.

Step 4: Proton transfer

Proton attacks on -NHR’ group so that it can leave effortlessly.

Step 5: Elimination of R’-NH2

Lone pairs of oxygen attack the carbon atom to push out the R’-NH2 group.

Step 6: Deprotonation of oxonium ion

Oxygen loses a proton to neutralise the charge.

Acid Catalysed Amide Hydrolysis

Base Catalysed Amide Hydrolysis

In a basic medium, amide interacts with the water molecule to give a carboxylic acid and the salt of ammonia or amine salt.

Mechanism:

  • In base catalysed amide hydrolysis, the amide is heated with boiling aqueous NaOH or KOH.
  • The nucleophilic hydroxide ion adds to the carbonyl carbon to form a tetrahedral intermediate.
  • Proton attacks the NR2 group.
  • Oxonium ion attacks the carbon atom.
  • HNR2 is cleaved.

Base Catalysed Amide Hydrolysis

Frequently Asked Questions on Amide Hydrolysis

Q1

What is an amide?

An amide is a functional group in which a carbonyl group is linked with the nitrogen atom by a single bond.

Amide is also known as derivatives of carboxylic acids having an OH group of COOH replaced by an NH2, NHR, NR2 of an amine.

Q2

What is acid catalysed amide hydrolysis?

It is a reaction of the amide with water in an acidic medium.

In an acidic medium, amide interacts with the water molecule to give a carboxylic acid and the salt of ammonia or amine salt.

Q3

What is base catalysed amide hydrolysis?

It is a reaction of the amide with water in a basic medium.

In a basic medium, amide interacts with the water molecule to give a carboxylic acid and the salt of ammonia or amine salt.

Q4

Is amide hydrolysis feasible?

Yes, amide hydrolysis is feasible. It interacts with water molecules either in an acidic medium or a basic medium.

In an acidic medium, amide interacts with the water molecule to give a carboxylic acid and the salt of ammonia or amine salt.

In a basic medium, amide interacts with the water molecule to give a carboxylic acid and the salt of ammonia or amine salt.

Q5

Explain the mechanism of a base catalysed amide hydrolysis?

In a basic medium, amide interacts with the water molecule to give a carboxylic acid and the salt of ammonia or amine salt.

Mechanism:

  • In base catalysed amide hydrolysis, the amide is heated with boiling aqueous NaOH or KOH.
  • The nucleophilic hydroxide ion adds to the carbonyl carbon to form a tetrahedral intermediate.
  • Proton attacks the NR2 group.
  • Oxonium ion attacks the carbon atom.
  • HNR2 is cleaved.

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