19.2 A2 Level

Nitriles and hydroxynitriles

8 flashcards to master this topic

Key Concept Flip

What reagents and conditions are required to produce a nitrile from a halogenoalkane?

Answer Flip

A halogenoalkane reacts with potassium cyanide (KCN) in ethanol, under reflux (heat). The cyanide ion acts as a nucleophile, replacing the halogen.

Calculation Flip

Write a balanced chemical equation for the production of ethanenitrile from chloroethane.

Answer Flip

CH₃CH₂Cl + KCN → CH₃CH₂CN + KCl

Key Concept Flip

Outline the mechanism for the formation of a hydroxynitrile from propanone.

Answer Flip

HCN reacts with propanone (in the presence of KCN catalyst and heat) via nucleophilic addition. The cyanide ion (CN⁻) attacks the carbonyl carbon, followed by protonation by HCN to form the hydroxynitrile.

Key Concept Flip

Why is KCN used as a catalyst in the formation of hydroxynitriles from aldehydes and ketones with HCN?

Answer Flip

KCN provides cyanide ions (CN⁻), which are better nucleophiles than HCN itself. This increases the rate of nucleophilic attack on the carbonyl carbon.

Key Concept Flip

Describe the hydrolysis of a nitrile with dilute acid, followed by acidification.

Answer Flip

Heating a nitrile with dilute acid (

Example: HCl or H₂SO₄) hydrolyses it to a carboxylic acid. The reaction produces a carboxylic acid and ammonium ions (NH₄⁺).
Key Concept Flip

Describe the hydrolysis of a nitrile with dilute alkali, followed by acidification.

Answer Flip

Heating a nitrile with dilute alkali (

Example: NaOH or KOH) hydrolyses it to a carboxylate salt. Acidification (. with HCl) then converts the salt into the corresponding carboxylic acid.
Key Concept Flip

What is the product of the alkaline hydrolysis of propanenitrile, followed by acidification with hydrochloric acid?

Answer Flip

The product is propanoic acid (CH₃CH₂COOH). Propanenitrile is first hydrolysed to sodium propanoate, which is then protonated to form propanoic acid upon acidification.

Key Concept Flip

Give the IUPAC name and structural formula of the product formed from the reaction of ethanal with HCN (with KCN as catalyst).

Answer Flip

The product is 2-hydroxypropanenitrile, with the structural formula CH₃CH(OH)CN.

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