Phenanthrene, Haworth Synthesis, Chemical Properties .pptx

Phenanthrene, Haworth Synthesis, Chemical Properties

1. Phenanthrene

2. Haworth synthesis

3. Chemical properties:- Phenanthrene undergoes addition reaction and electrophilic substitution reaction at 9 & 10 position. This can be understood by examining the intermediate carbocation obtained due to attack of electrophile at C1,C2 and C9 position. The resonance energy of phenanthrene is 92 k.cal/mole while the resonance energy of naphthalene is 61 k.cal/mole that of benzene is 36 k.cal/mole.

4. The intermediate carbocation obtained by the attack of electrophile at C9 position contains two benzene rings hence the loss of resonance energy only between 20 k.cal/mole . Hence this intermediate carbocation is more stable and intermediate carbocation obtained by the attack of electrophile at C1 & C2 position in which a naphthalene is obtained & a loss of resonance energy 31 k.cal/mole.

5. Nitration:-

6. Chlorination:-

7. Friedel -Crafts Acylation :-

8. Resonance structure of Phenanthrene :- According to resonance theory phenanthrene is consider as a resonance hybrid of following five resonating structure-

9. Note:-C1-C2 bond has 3/5 i.e. 60% double bond character C2-C3 bond has 2/5 i.e. 40% double bond character. C9-C10 bond has 4/5 i.e. 80% double bond character.

10. Carcinogenic hydrocarbons:- An organic compound that is likely to cause cancer and contains only carbon and hydrogen that can be arranged in rows,rings or both and connected by single,double or triple bonds. carcinogenic hydrocarbons are often found in petroleum, natural gas and coal and are capable of causing cancer.