Synthesis of Naphthalene

Q: Synthesis of Naphthalene from 4-phenyl 3-butenoic acid

When 4-phenyl 3-butenoic acid is heated with conc. sulphuric acid, 1-naphthol is formed. This on distillation with Zn dust gives Naphthalene.

Haworth Synthesis of Naphthalene

Benzene and succinic anhydride are heated in the presence of AlCl₃ to form β-benzoylpropionic acid which on treated with Zn-Hg/HCl to form γ-phenylbutyric acid. γ-Phenylbutyric acid is now heated with concentrated sulphuric acid or phosphoric acid to form tetralone. Tetralone is now heated with Zn-Hg/HCl to form tetralin which on heated with Se or Pd to yield Naphthalene.