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Unformatted text preview: CHEMISTRY 3B Professor Peter Vollhardt 9/11/08 Lecture 5 ASUC Lecture Notes Online is the only authorized note-taking service at UC Berkeley. Do not share, copy or illegally distribute (electronically or otherwise) these notes. Our student-run program depends on your individual subscription for its continued existence. These notes are copyrighted by the University of California and are for your personal use only. D O N O T C O P Y Sharing or copying these notes is illegal and could end note taking for this course. LECTURE CONJUGATED CYCLOPOLYENES: ANNULENES Hückel’s Rule is used to determine aromaticity. If a compound has 4n+2 pi electrons then it is aromatic . If it has 4n pi electrons then it is antiaromatic . Interruption of cyclic conjugation makes it nonaromatic . Using H NMR, we see that aromatic systems show deshielded outer hydrogens and shielded inner hydrogens. Antiaromatic systems, on the other hand, show the reverse: shielded outer and deshielded inner hydrogens....
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This note was uploaded on 10/07/2010 for the course CHEM 3b taught by Professor Pederson during the Fall '08 term at University of California, Berkeley.
- Fall '08