Question

Explain Haworth's synthesis of naphthalene

Answer 1

Haworth's Synthesis.

• Naphthalene is a polycyclic hydrocarbon with a chemical formula ${\mathrm{C}}_{10}{\mathrm{H}}_8$.
• It can be synthesized by Haworth's process. Steps of the process is given below

Step-1: Benzene is treated with Succinic anhydride in the presence of ${\mathrm{AlCl}}_3$which gives 3-benzoylpropanoic acid.

Step-2: By Clemmenson’s reaction 3-benzoylpropanoic acid is converted to 4-phenylbutanoic acid.

Step-3: 4-phenylbutanoic acid. is heated in presence of sulphuric acid. the compound get dehydrated and releases one molecule of water and forms 1-tetralene or α-tetralene .

Step-4: The Clemmenson synthesis of α-tetralene produces Tetralin or tetrahydronaphthalene.

Step-5: Tetrahydronaphthalene on heating with Selenium $\left(\mathrm{Se}\right)$ or Palladium$\left(\mathrm{Pd}\right)$ produces Nephthalene.