Definitions [3]
Definition: Primary Amines
Primary amines (1°) are the ammonia derivatives in which one H-atom has been replaced by one alkyl or aryl group.
Definition: Tertiary Amines
Tertiary amines (3°) are the ammonia derivatives in which three hydrogen atoms have been replaced by three alkyl or aryl group.
Definition: Secondary Amines
Secondary amines (2°) are the ammonia derivatives in which two hydrogen atoms have been replaced by two alkyl or aryl groups.
Key Points
Key Points: Classification of Amines
- Amines overview: Amines are derivatives of ammonia (NH₃) where one or more H-atoms are replaced by alkyl/aryl groups; they can be saturated or unsaturated.
- Classification by source: Aliphatic amines (e.g., CH₃–NH₂, methylamine) and Aromatic amines (e.g., C₆H₅–NH₂, aniline).
- Classification by H-substitution: Primary (1°, –NH₂, e.g., methylamine), Secondary (2°, –NH–, e.g., dimethylamine), and Tertiary (3°, –N–, e.g., trimethylamine).
- Sub-types of 2° and 3° amines: Simple/symmetrical (same groups, e.g., (C₂H₅)₂NH, (C₂H₅)₃N) and Mixed/unsymmetrical (different groups, e.g., C₂H₅–NH–CH₃, C₂H₅–N(CH₃)₂).
- Examples of each class: 1° – n-butylamine, sec-butylamine, tert-butylamine, aniline; 2° – dimethylamine, diethylamine, diphenylamine; 3° – trimethylamine, triethylamine, triphenylamine.
Key Points: Diazonium Salts
- Diazonium salts: Compounds with the general formula ArN₂⁺X⁻ (e.g., C₆H₅N₂⁺Cl⁻ = Benzenediazonium chloride).
- X⁻ = Cl⁻, Br⁻, HSO₄⁻, NO₃⁻, BF₄⁻, etc.
- Benzenediazonium chloride: Colourless crystalline solid; readily soluble in water; stable in cold but decomposes on warming; decomposes easily in dry state.
- Benzenediazonium fluoroborate: Water insoluble, stable at room temperature.
- The stability of arenediazonium ions is due to resonance — the positive charge is delocalised into the benzene ring.
