Amides are a class of organic compounds in which a carbonyl group (C=O) is directly bonded to a nitrogen atom (–NH₂, –NHR, or –NR₂). They are derivatives of carboxylic acids, where the –OH group is replaced by an –NH₂ or substituted amino group.
1. General Structure
- The general formula is R–CO–NH₂ for primary amides.
- Secondary amides: R–CO–NHR
- Tertiary amides: R–CO–NR₂
2. Types of Amides
- Primary Amides – Nitrogen has two hydrogens (–CONH₂).
- Secondary Amides – Nitrogen has one hydrogen and one alkyl/aryl group (–CONHR).
- Tertiary Amides – Nitrogen has two alkyl/aryl groups (–CONR₂).
3. Characteristics
- Polar due to the carbonyl and nitrogen.
- Can form hydrogen bonds (especially primary and secondary amides).
- Generally have higher boiling points than amines or hydrocarbons of similar size.
- Less basic than amines because the lone pair on nitrogen is partially delocalized into the carbonyl group.
4. Example
- Primary amide: Formamide (H–CONH₂)
- Secondary amide: N-methylacetamide (CH₃–CO–NHCH₃)
- Tertiary amide: N,N-dimethylacetamide (CH₃–CO–N(CH₃)₂)
In short, amides are carbonyl compounds where nitrogen replaces the –OH of a carboxylic acid, and their properties are influenced by the nitrogen and the carbonyl group.