Dolbier HW Solutions 264

Dolbier HW Solutions 264 - highly stabilized. The...

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11.16 Resonance structures are generated for cyclopentadienide anion by moving the unshared electron pair from the carbon to which it is attached to a position where it becomes a shared electron pair in a p bond. 11.17 The process is an acid base reaction in which cyclopentadiene transfers a proton to amide ion (the base) to give the aromatic cyclopentadienide anion. The sodium ion (Na 1 ) has been omitted from the equation. 11.18 ( b ) Cyclononatetraenide anion has 10 p electrons; it is aromatic. The 10 p electrons are most easily seen by writing a Lewis structure for the anion: there are 2 p electrons for each of four double bonds, and the negatively charged carbon contributes 2. 11.19 Indole is more stable than isoindole. Although the bonding patterns in both f ve-membered rings are the same, the six-membered ring in indole has a pattern of bonds identical to benzene and so is
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Unformatted text preview: highly stabilized. The six-membered ring in isoindole is not of the benzene type. 11.20 The pre f x benz- in benzimidazole (structure given in text) signi f es that a benzene ring is fused to an imidazole ring. By analogy, benzoxazole has a benzene ring fused to oxazole. Similarly, benzothiazole has a benzene ring fused to thiazole. S N Benzothiazole N H N Benzimidazole O N Benzoxazole N H Indole more stable NH Isoindole less stable Six-membered ring corresponds to benzene. Six-membered ring does not have same pattern of bonds as benzene. 2 H H 1 NH 2 2 1 NH 3 H 2 1,3-Cyclopentadiene Amide ion Cyclopentadienide anion Ammonia H H H H H 2 H H H H H 2 H H H H H 2 H H H H H 2 H H H H H 2 258 ARENES AND AROMATICITY...
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This note was uploaded on 09/26/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.

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