14. AROMATIC COMPOUNDS. (approx. lecture time: 2 lectures) Topics covered:14.1-14.7A,14.7D,14.8A,14.9. Benzene more than just cyclic conjugation: aromatic stabilization
The Halifax Explosion of 1917 The Halifax Explosionoccurred on Thursday, December 6, 1917, when the city was devastated by the huge detonation of the SS Mont-Blanc, a French cargo ship fully loaded with wartime explosives, which accidentally collided with the Norwegian ship the SS Imo in "The Narrows" section of Halifax Harbour. About 2,000 people were killed and over 9,000 people were injured. The Halifax Explosion remains the World’s largest accidental explosion. If you are from Nova Scotia, you will definitely know about it! Picric Acid TNT; 2,4,6-trinitrotoluene
Joining benzene rings to each other will always create an aromatic system! “mothballs” potent carcinogen
Hückel’s 4n + 2 p Electron Rule Hückel’s rule is concerned with compounds containing oneplanarringin which each atom has a pzorbitalas in benzene. “Planar monocyclic rings containing 4n + 2 p electrons, where n = 0, 1, 2, 3, and so on (i.e., rings containing 2, 6, 10, 14 . .p electrons) should be aromatic, i.e., show exceptional stability relative to similar systems without this electron count”
Examples of Hückel’s4n + 2 p Electron Rule Cyclooctatetraene
Imidazole Imidazole is an aromatic compound that is important in biological systems. The two nitrogens are not equivalent! Learn how to tell them apart.
Sunblocks: just “blocks” the sun’s rays. Use TiO2 and ZnO2. But will look geeky. Sunscreens and Sunblocks(Organic chemists can become wealthy without making drugs) Avobenzone PABA Oxybenzone Sunscreens: organic compounds that converts the UV light into thermal energy. These are “designer compounds” so we can charge much more than inorganics. They also have many industrial uses! 4-MBC Tinosorb M