Weak base equilibrium

Overview

Amines are weak bases in water and form alkylammonium and hydroxide ions.

Transformation

Amines → Aqueous alkylammonium ions

Equation

RNH2 + H2O <-> RNH3+ + OH-

Reagents

water

Environment

aqueous solution

Reaction class

acid-base equilibrium

Mechanism

proton transfer

Evidence level

textbook core

Scope and limitations

Scope

Primary amines act as Brønsted-Lowry bases by accepting a proton from water.

Limitations

The equilibrium position depends on amine structure and solution conditions.

Related reactions

• Amination: Chloroalkanes → Amines

  Ammonia substitutes chloride to form a primary amine; excess ammonia limits further alkylation.

• Amination: Bromoalkanes → Amines

  Ammonia substitutes bromide to form a primary amine; excess ammonia limits further alkylation.

• Amination: Iodoalkanes → Amines

  Ammonia substitutes iodide to form a primary amine; excess ammonia limits further alkylation.

• Alkylation: Amines → Quaternary ammonium compounds

  Amines can be further alkylated to permanent cationic quaternary ammonium groups used in antimicrobial and ion-exchange materials.

• Reduction: Nitriles → Amines

  Nitriles can be reduced to primary amines, separating the amine feedstock route from later amide or materials chemistry.

• Acylation co reactant: Amines → N-substituted amides

  Amines are acylated by acyl chlorides to form N-substituted amides.

• Salt formation: Amines → Amine salts

  Amines react with acids to form alkylammonium salts.

• Copper(II) complex formation: Amines → Copper-amine complexes

  Amines react with aqueous copper(II) ions and form a deep-blue complex in excess amine.

References

1. Pearson Edexcel Level 3 Advanced GCE in Chemistry specificationPearson Education Limited · Pearson qualifications · 2024

   Supports the textbook-core organic reaction routes used for displayed route and mechanism content.