Phenanthrene by Mr. pradeep swarnkar

Phenanthrene by Mr. pradeep swarnkar

• 1.
  KOTA COLLEGE OF PHARMACY Phenanthrene Mr.Pradeep Swarnkar Associate Professor
• 2.
  Phenanthrene is apolycyclic aromatic hydrocarbon composed of three fused benzene rings. In its pure form, it is found incigarette smoke and is a known irritant , photosensitizing skin to light. Phenanthrene appears as a white powder having blue fluorescence. Phenanthrene is the backbone of morphine.
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  Resonance structure ofphenanthrene: Like anthracene , phenanthrene is a planar molecule. All fourteen carbon atoms are sp2 hybridized. The sp2 orbitals overlap with each other and with s orbitals of ten hydrogen atoms to C-C and C-H σ bonds . Each carbon atom also possesses a p orbital and these are perpendicular to the plane containing the bonds. The lateral overlap of these p orbital produces a π molecular orbital containing ten electrons. Phenanthrene shows aromatic properties because the resulting π molecular orbital satisfies the Huckel`s rule (4n+2).
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  Resonance energy =91Kcal/mole
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  Preparation of phenanthrene: (i)Haworth phenanthrene synthesis:
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  Reaction of Phenanthrene:
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  Reduction:
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  Oxidation:
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  When oxidized withchromic acid in acetic acid phenanthrene yields a diketone, phenanthraquinone which upon further oxidation gives diphenic acid.
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  Bromination:
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  Electrophilic addition versuselectrophilic substitution Br2,,Fe Br3 Br2
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  The reactivity ofthe 9- and 10-positions toward electrophilic attack, whether reaction leads to substitution or addition, is understandable since the initially formed carbocation is the most stable one, in which aromatic sextets are preserved in two of the three rings. This carbocation can then either (a) give up a proton to yield the substitution product, or (b) accept a nucleophile to yield the addition product.
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  Derivatives of phenanthrene:
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  Papaverine belongs tothe class of medicines called as vasodilators. It acts on muscles of blood vessels, resulting in expansion of blood vessels and thus increasing the blood flow to heart and the affected organs
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  Medicinal uses ofPhenanthrene:
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  1. Anthraquinone isused in the manufacture of alizarin and several other dyes.
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  2. Antifungal
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  3. Steroid moietycontain phenanthrene nucleus.
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  4. Sex hormonesand bile acids. 5. Steroid used as oral contraceptive and antiinflamatory agent. 6. Cardiac glycosides, morphine, codeine.