An amine is a compound containing the -NH 2 functional group, formed by nucleophilic substitution of a halogenoalkane with ammonia.

What reagents and conditions are needed to produce an amine from a halogenoalkane?

The halogenoalkane is heated under pressure with ethanolic ammonia (NH 3 dissolved in ethanol).

True or False? The nitrogen atom in ammonia acts as a nucleophile because it has a lone pair of electrons.

True. The lone pair on the nitrogen of NH 3 attacks the partial positive carbon of the C-X bond in the halogenoalkane, replacing the halogen in a nucleophilic substitution reaction.

In the nucleophilic substitution of a halogenoalkane by NH 3 , the .......... atom of ammonia attacks the .......... charged carbon of the C-X bond.

In the nucleophilic substitution of a halogenoalkane by NH 3 , the nitrogen atom of ammonia attacks the partially positive charged carbon of the C-X bond.

Why does the C-X bond in a halogenoalkane have a partial positive charge on the carbon?

The halogen atom is more electronegative than carbon, so it draws electron density away from the C-X bond towards itself. This gives the carbon a partial positive charge (δ+) and the halogen a partial negative charge (δ-).

True or False? Reacting bromoethane with ethanolic ammonia under heat and pressure produces ethylamine and hydrobromic acid.

True. The NH 3 substitutes the Br in bromoethane via nucleophilic substitution, forming ethylamine (CH 3 CH 2 NH 2 ) and hydrobromic acid (HBr) as the byproduct.

Amines are produced from halogenoalkanes by .......... substitution, in which the halogen is replaced by an .......... group.

Amines are produced from halogenoalkanes by nucleophilic substitution, in which the halogen is replaced by an amine group.

A nucleophile is an electron-pair donor that attacks electron-deficient (partial positive) atoms. The nitrogen lone pair in NH 3 acts as a nucleophile in the production of amines.

Why is an ethanolic solution of ammonia used rather than an aqueous solution to produce amines from halogenoalkanes?

Aqueous ammonia contains water, which can act as a nucleophile and cause hydrolysis of the halogenoalkane, producing an alcohol as a competing product. Using ethanolic ammonia removes water, ensuring NH 3 is the only nucleophile present and the reaction selectively produces the amine .

A LevelChemistryCambridge (CIE)Flashcards19. Nitrogen CompoundsPrimary Amines

Primary Amines (Cambridge (CIE) A Level Chemistry): Flashcards

Exam code: 9701

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FrontMaking Amines
Define amine.

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Cards in this collection (9)

Define amine.
An amine is a compound containing the -NH₂ functional group, formed by nucleophilic substitution of a halogenoalkane with ammonia.
What reagents and conditions are needed to produce an amine from a halogenoalkane?
The halogenoalkane is heated under pressure with ethanolic ammonia (NH₃ dissolved in ethanol).
True or False?
The nitrogen atom in ammonia acts as a nucleophile because it has a lone pair of electrons.
True.
The lone pair on the nitrogen of NH₃ attacks the partial positive carbon of the C-X bond in the halogenoalkane, replacing the halogen in a nucleophilic substitution reaction.
In the nucleophilic substitution of a halogenoalkane by NH₃, the .......... atom of ammonia attacks the .......... charged carbon of the C-X bond.
In the nucleophilic substitution of a halogenoalkane by NH₃, the nitrogen atom of ammonia attacks the partially positive charged carbon of the C-X bond.
Why does the C-X bond in a halogenoalkane have a partial positive charge on the carbon?
The halogen atom is more electronegative than carbon, so it draws electron density away from the C-X bond towards itself. This gives the carbon a partial positive charge (δ+) and the halogen a partial negative charge (δ-).
True or False?
Reacting bromoethane with ethanolic ammonia under heat and pressure produces ethylamine and hydrobromic acid.
True.
The NH₃ substitutes the Br in bromoethane via nucleophilic substitution, forming ethylamine (CH₃CH₂NH₂) and hydrobromic acid (HBr) as the byproduct.
Amines are produced from halogenoalkanes by .......... substitution, in which the halogen is replaced by an .......... group.
Amines are produced from halogenoalkanes by nucleophilic substitution, in which the halogen is replaced by an amine group.
Define nucleophile.
A nucleophile is an electron-pair donor that attacks electron-deficient (partial positive) atoms. The nitrogen lone pair in NH₃ acts as a nucleophile in the production of amines.
Why is an ethanolic solution of ammonia used rather than an aqueous solution to produce amines from halogenoalkanes?
Aqueous ammonia contains water, which can act as a nucleophile and cause hydrolysis of the halogenoalkane, producing an alcohol as a competing product. Using ethanolic ammonia removes water, ensuring NH₃ is the only nucleophile present and the reaction selectively produces the amine.

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