Phenanthrene is a polycyclic aromatic hydrocarbon composed of three fused benzene rings. It appears as a white powder with blue fluorescence. Phenanthrene shows aromatic properties and is the backbone molecule for morphine. It undergoes reactions like oxidation, reduction, bromination, and electrophilic addition or substitution. Derivatives of phenanthrene like papaverine are used as vasodilators to increase blood flow. Phenanthrene and its derivatives have several medicinal uses including manufacturing dyes, acting as antifungals, and being components of steroids, sex hormones, bile acids, and cardiac glycosides.

1. KOTA COLLEGE
OF PHARMACY
Phenanthrene
Mr. Pradeep Swarnkar
Associate Professor

2. Phenanthrene is a polycyclic 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.

4. Resonance structure of phenanthrene:
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).

5. Resonance energy = 91Kcal/mole

6. Preparation of phenanthrene:
(i) Haworth phenanthrene synthesis:

7. Reaction of Phenanthrene:

8. Reduction:

9. Oxidation:

10. When oxidized with chromic acid in acetic acid phenanthrene yields a diketone,
phenanthraquinone which upon further oxidation gives diphenic acid.

11. Bromination:

12. Electrophilic addition versus electrophilic substitution
Br2,,Fe Br3
Br2

14. The reactivity of the 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.

15. Derivatives of phenanthrene:

16. Papaverine belongs to the 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

18. Medicinal uses of Phenanthrene:

19. 1. Anthraquinone is used in the manufacture of alizarin and several other dyes.

20. 2. Antifungal

21. 3. Steroid moiety contain phenanthrene nucleus.

22. 4. Sex hormones and bile acids.
5. Steroid used as oral contraceptive and antiinflamatory agent.
6. Cardiac glycosides, morphine, codeine.