Thread: NMR of Naphthalene: why are the alpha-protons more downfield than the beta- protons?
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Unread 12-24-2002, 12:07 PM
Cubbi5362 Cubbi5362 is offline
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Default Please help!! NMR of Naphthalene: why are the alpha-protons more downfield than the beta- protons?
In aromatics, the protons are deshielded due to ring currents. The alpha protons in naphthalene are close enough to the other ring to feel BOTH ring currents. The beta protons only feel one ring's current. Look at anthracene, where the protons on the central ring are even further deshielded (into 8.4 ppm), under the combined effect of three rings.Here's a recent publication on this topic: http://www.biomedsearch.com/nih/Understanding-ring-current-effects-magnetic/18711723.html

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