Polynuclear Aromatics - Organic Chemistry II - Lecture Slides, Slides of Organic Chemistry

Download Polynuclear Aromatics - Organic Chemistry II - Lecture Slides and more Slides Organic Chemistry in PDF only on Docsity! Polynuclear Aromatics Naphthalene Anthracene Phenanthrene ® docsity.com 1 2 3 45 6 7 8 9 10 Napthalene docsity.com Naphthalene, reactions: 1) oxidation: O O O O O CrO3 HOAc, 25o O2, V2O5 460-480o 1,4-naphthoquinone phthalic anhydride docsity.com Note: Because naphthalene is sensitive to oxidation, you cannot make naphthoic acids via oxidation of a side chain. [oxid.] CH3 CH3 O O CCH3 O NaOI COOH docsity.com 2. Reduction: Na, EtOH 78o Na, i-PeOH 132o (xs) H2, Pt heat, pressure 1,4-dihydronaphthalene tetrahydronaphthalene (tetralin) decalin docsity.com Why is EAS in naphthalene mostly to the alpha-position?   docsity.com EAS in syntheses of substituted naphthalenes: Alpha-substitution via halogenation or nitration. Br MgBr NO2 NH2 Br2 CCl4 HNO3 Mg H2/Ni docsity.com Beta-substitution via high temp sulfonation or Friedel-Crafts acylation in nitrobenzene. SO3H ONa OHNH2 C CH3 O COOH C NH2 O NH2 OH-, 3000 H+ NH3 heat,pressure OI- SOCl2; then NH3 OBr- docsity.com OH OH NO2 NO2 NO2 NO2NO2 HNO3 N2 N N + + docsity.com Haworth Synthesis of naphthalene O O O O HO2C AlCl3 + Zn(Hg) HCl HO2C HF or PPA O Zn(Hg) HCl Pd CO2, heat docsity.com Substituted naphthalenes via Haworth synthesis: CH3 O O O + AlCl3 CH3 C O COOH CH3 beta- O + RMgX OHR H+ Pd, CO2 heat a) use a substituted benzene G = -R, -X, -OCH3 b) Grignard RR alpha- docsity.com 3 2 1 4 10 9 8 7 6 5 3 2 1 4 109 8 7 6 5 Phenanthrene 14 pi e-, total of five resonace structures Heat of hydrogenation is -92 Kcal/mole lower than predicted. 2 x -36 = -72 -92 -(-72) = -20 Kcal/mole to remove the aromaticity of the middle ring. docsity.com K2Cr2O7 H+ K2Cr2O7 H+ O O OO 9,10-antraquinone 9,10-penanthrone Oxidation: docsity.com Reduction: O00 wm OVO 9,10-dihyroanthracene OM - OHO 9,10-dihydrophenanthrene ® docsity.com Haworth synthesis of anthracene O O HO2C O O O O + AlCl3 H2SO4 Zn(Hg) HCl Pd, CO2, heat phthalic anhydride docsity.com Haworth synthesis of phenanthrene O O COOH O HOOC + O O + AlCl3 succinic anhydride Zn(Hg), HCl COOH HOOC + HF O O + Pd, CO2, heat Zn(Hg),HCl docsity.com