Explain Haworth synthesis of naphthalene

Naphthalene C10H8 is an organic compound having the simplest polycyclic aromatic hydrocarbon. It is a white crystalline solid with a characteristic odour. Naphthalene’s structure consists of a fused pair of benzene rings. It is best known as the main ingredient of traditional mothballs. It can be synthesized by Haworth synthesis, the steps are as follows:

  1. The Friedel craft acylation reaction of benzene with succinic anhydride gives 3 benzoylpropionic acid.
  2. Second step is the Clemmenson’s reaction with 3-benzoylpropionic acid which gives 4-phenylebutanoic acid.
  3. On heating this product in the presence of concentrated sulphuric acid results in the formation of ring structure of α-tetralene by the ellimination of water molecule.
  4. The Clemmenson reaction of α-tetralene gives tetrahydronaphthalene.
  5. Dehydrogenation of tetrahydronaphthalene in the presence of selenium yields naphthalene.

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