Aromatic hydrocarbons are organic compounds that contain at least one aromatic ring, typically a benzene ring (a six-carbon ring with alternating double bonds that is stabilized by resonance). Here are some common examples:
1. Benzene and its derivatives:
- Benzene (C₆H₆) – the simplest aromatic hydrocarbon.
- Toluene (C₆H₅CH₃) – benzene with a methyl group.
- Aniline (C₆H₅NH₂) – benzene with an amino group.
- Phenol (C₆H₅OH) – benzene with a hydroxyl group.
2. Polycyclic aromatic hydrocarbons (PAHs):
These contain multiple fused benzene rings. Examples:
- Naphthalene (C₁₀H₈) – two fused benzene rings (used in mothballs).
- Anthracene (C₁₄H₁₀) – three linearly fused benzene rings.
- Phenanthrene (C₁₄H₁₀) – three fused benzene rings in an angular arrangement.
- Pyrene (C₁₆H₁₀) – four fused benzene rings.
3. Heterocyclic aromatic compounds (aromatic rings containing other elements like N, O, or S):
- Pyridine (C₅H₅N) – benzene-like ring with one nitrogen atom.
- Furan (C₄H₄O) – five-membered ring with oxygen.
- Thiophene (C₄H₄S) – five-membered ring with sulfur.
So basically, any compound with a stable, conjugated cyclic π-electron system (following Hückel’s rule) can be considered aromatic.