Amines (A-level only) revision notes

Amines Overview

Amines are classified based on the number of carbon groups attached to the nitrogen atom:

• Primary amines: One carbon group (R-NH2)
• Secondary amines: Two carbon groups (R2-NH)
• Tertiary amines: Three carbon groups (R3-N)

Basicity of Amines

Amines are basic due to the lone pair of electrons on the nitrogen atom. This lone pair can accept protons (H+), making amines stronger bases than ammonia in many cases. The basicity can be influenced by the presence of alkyl groups, which donate electron density to the nitrogen, enhancing its ability to bond with protons.

Comparison with Ammonia

While ammonia (NH3) is a simple amine, its basicity is often compared to that of primary and secondary amines. The presence of electron-donating groups in amines increases their basicity compared to ammonia, while electron-withdrawing groups decrease it.

Preparation and Reactions

Amines can be prepared through various methods, including:

• Reduction of nitro compounds
• Alkylation of ammonia
• Reduction of amides

Reactions of amines include:

• Acid-base reactions: Amines react with acids to form ammonium salts.
• Nucleophilic substitution: Amines can act as nucleophiles in reactions with alkyl halides.