The Phenanthrene is prepared by the following methods:
1. Haworth Synthesis of Phenanthrene: There are five steps involved in the Haworth Synthesis process:
- Step 1: Naphthalene is treated with succinic anhydride in the presence of aluminum chloride to form napthoylpropionic acid (Friedal craft acylation).
- Step 2: Napthoylpropionic acid is treated with amalgamated Zinc in HCl to give napthobutyric acid (Clemmensen reduction).
- Step 3: Napthobutyric acid is heated with sulfuric acid to give 1-keto-1,2,3,4-tetrahydrophenanthrene (ring closure reaction).
- Step 4: 1-keto-1,2,3,4-tetrahydrophenanthrene is reacted with amalgamated zinc in the presence of HCl to give 1,2,3,4-tetrahydrophenanthrene (Clemmensen reduction).
- Step 5: 1,2,3,4-tetrahydro phenanthrene is heated with palladium to yield phenanthrene.
2. By Dibenzal: Phenanthrene can be produced by passing dibenzal through a red-hot tube.
3. From 2,2-Dimethyldiphenyl: Phenanthrene can be synthesized by cyclodehydrogenation of 2,2-Dimethyldiphenyl using sulfur.
Conclusion:
In conclusion, there are several methods for preparing phenanthrene, each offering its unique pathway to synthesizing this important aromatic hydrocarbon. The Haworth Synthesis process involves a series of steps, including Friedel-Crafts acylation, Clemmensen reduction, and ring closure reactions, ultimately yielding phenanthrene from naphthalene. Additionally, phenanthrene can be obtained through alternative routes, such as the cyclo dehydrogenation of dibenzal or 2,2-Dimethyldiphenyl using sulfur. These methods provide valuable approaches for synthesising phenanthrene, enabling its utilization in various applications in organic synthesis, pharmaceuticals, and materials science.