Describe three methods for the preparation of phenol, with equations.

1. 1 · Open with the methods. Phenol is made from chlorobenzene, benzenesulphonic acid, diazonium salts or cumene.
2. 2 · From chlorobenzene.
   • C₆H₅Cl + 2NaOH → C₆H₅ONa + NaCl + H₂O (623 K, 300 atm)
   • C₆H₅ONa + HCl → C₆H₅OH + NaCl
3. 3 · From benzenesulphonic acid.
   • C₆H₆ + H₂SO₄ (oleum) → C₆H₅SO₃H + H₂O
   • C₆H₅SO₃H + 3NaOH (molten) → C₆H₅ONa + Na₂SO₃ + 2H₂O
   • Acidify to phenol
4. 4 · From a diazonium salt. C₆H₅N₂⁺Cl⁻ + H₂O (warm) → C₆H₅OH + N₂ + HCl.
5. 5 · From cumene.
   • C₆H₅CH(CH₃)₂ + O₂ → C₆H₅C(CH₃)₂OOH
   • C₆H₅C(CH₃)₂OOH (dilute acid) → C₆H₅OH + CH₃COCH₃
6. 6 · Link to real life. Phenol makes Bakelite; the acetone by-product is a common solvent.
7. 7 · Close in one line. So the cumene process is the main industrial route, because it gives two useful products.

Scoring tip: Write 'by-product: acetone' clearly in the cumene answer.