Heterocyclic aromatic compounds pyridine and pyrrole

Heterocyclic aromatic compounds pyridine and pyrrole - 3...

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Heterocyclic aromatic compounds pyridine and pyrrole, electrons on the nitrogen in pyridime are not counted as pi electrons for vinylic and allylic electrons are counted as pi electrons in the case of pyrrole Aromatic ions reacting 1,3-cyclopentadiene with 2Na will take off 2 hydrognes making it an ion Rules for counting pi electrons 1. each atomthat is part of a double bond contributes one pi electron 2. vinylic unshared electron pairs do not contribute to the pi electron count
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Unformatted text preview: 3. allylic unshared electron pairs contribute two electrons to the pi electron count if they occuy an orbital that is parallel to the other p oribitals in the molecule 4. an atom with na empty p orbital can be part of a continuous aromatic pi elertorn system and not contribute any pi electrons if allylic lone pairs are outside ring they are in p orbital’s antiaromatic compounds that contain planar, continuous rings of 4n pi electrons are especially unstable...
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This note was uploaded on 04/26/2011 for the course CHEM 221 taught by Professor Sffe during the Spring '11 term at Dickinson.

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