Dolbier HW Solutions 279

Dolbier HW Solutions 279 - 273 ARENES AND AROMATICITY(c...

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( c ) Cycloundecapentaenyl cation is aromatic. It includes a completely conjugated p system which contains 10 p electrons (10 equals 4 n 1 2 where n 5 2). ( d ) Cycloundecapentadienide anion is not aromatic. It contains 12 p electrons and thus does not satisfy the (4 n 1 2) rule. 11.45 ( a ) The more stable dipolar resonance structure is A because it has an aromatic cyclopentadienide anion bonded to an aromatic cyclopropenyl cation. In structure B neither ring is aromatic. ( b ) Structure D can be stabilized by resonance involving the dipolar form. Comparable stabilization is not possible in structure C because neither a cyclopropenyl sys- tem nor a cycloheptatrienyl system is aromatic in its anionic form. Both are aromatic as cations. 11.46 ( a ) This molecule, called oxepin, is not aromatic. The three double bonds each contribute 2 p electrons, and an oxygen atom contributes 2 p electrons to the conjugated system, giving a
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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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