What is a Nitrile?
Nitrile is an organic compound having a −C≡N functional group.
It is found in methyl cyanoacrylate, which is used as super glue. Rubber also contains nitrile, later used in the latex-free laboratory and medical gloves. Nitrile rubber is also used in automation, as it is fuel and oil resistant.
The organic compound with numerous nitrile groups is often called cyano hydrocarbons. In contrast, the inorganic compound with a nitrile group is often called cyanides.
Table of Content
- The Hydrolysis of Nitriles
- Acidic Hydrolysis of Nitriles
- Alkaline Hydrolysis of Nitriles
- Frequently Asked Questions – FAQs
The Hydrolysis of Nitriles
Nitriles get hydrolysed in two steps; amides are formed first. While in the second step, an ammonium salt of a carboxylic acid is formed.
For example, Ethanenitrile on getting hydrolysed gives ethanamide in the first step while ammonium ethanoate in the second step.
CH3CN + H2O → CH3CONH2 → CH3COONH4
In reality, the reaction between nitriles and water doesn’t occur efficiently. We have to heat nitrile with either dilute acid or alkali for a reaction. The end product is similar in both cases, but the nature of the product may vary depending on the reaction condition.
Acidic Hydrolysis of Nitriles
Under acidic conditions, instead of getting an ammonium salt, carboxylic acid is formed.
For example, Ethanenitrile on getting hydrolysed in hydrochloric acid gives ethanamide in the first step, while ethanoic acid and ammonium chloride in the second step.
CH3CN + 2H2O + HCl ⟶ CH3COOH + NH4Cl
Ethanoic acid is formed instead of ammonium ethanoate because ethonate ions in the ammonium ethanoate react with the hydrogen ions liberated by hydrochloric acid to form ethanoic acid. Ethanoic acid is a weak acid that tends to hang hydrogen ions.
Alkaline Hydrolysis of Nitriles
Under alkaline conditions, instead of getting an ammonium salt, sodium salt of the carboxylic acid is formed.
For example, Ethanenitrile on getting hydrolysed in sodium hydroxide gives ethanamide in the first step, while sodium salt of ethanoic acid and ammonia gas in the second step.
CH3CN + H2O + NaOH ⟶ CH3COONa– + NH3
The ammonia gas is liberated in the second step because of a reaction between ammonium and hydroxide ions.
If carboxylic acid is the desired product, then the ethanenitrile must be reacted in the acidic condition. The reaction between ethanoate ions and hydrogen ions is already explained above.
Frequently Asked Questions on Hydrolysis of Nitriles
What is nitrile?
Nitrile is an organic compound having a −C≡N functional group. The organic compound with numerous nitrile groups is often called cyano hydrocarbons. In contrast, the inorganic compound with a nitrile group is often called cyanides.
What is the product of hydrolysis of nitrile?
Nitrile gets hydrolysed in two steps; amides are formed first. While in the second step, an ammonium salt of a carboxylic acid is formed.
For example, Ethanenitrile on getting hydrolysed gives ethanamide in the first step, while ammonium ethanoate in the second step.
CH3CN + H2O → CH3CONH2 → CH3COONH4
What happens when nitriles undergo acid hydrolysis?
Under acidic conditions, instead of getting an ammonium salt, carboxylic acid is formed.
For example, Ethanenitrile on getting hydrolysed in hydrochloric acid gives ethanamide in the first step, while ethanoic acid and ammonium chloride in the second step.
CH3CN + 2H2O + HCl ⟶ CH3COOH + NH4Cl
What happens when nitriles undergo alkaline hydrolysis?
Under alkaline conditions, instead of getting an ammonium salt, sodium salt of the carboxylic acid is formed.
For example, Ethanenitrile on getting hydrolysed in sodium hydroxide gives ethanamide in the first step, while sodium salt of ethanoic acid and ammonia gas in the second step.
CH3CN + H2O + NaOH ⟶ CH3COONa– + NH3
Under acidic conditions, why was free acid formed rather than ammonium salt?
Ethanoic acid is formed instead of ammonium ethanoate because ethanoate ions in the ammonium ethanoate react with the hydrogen ions liberated by hydrochloric acid to form ethanoic acid.
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