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Topic: Woodward-Fieser Rules  (Read 5202 times)

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Offline Covfe₂

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Woodward-Fieser Rules
« on: October 01, 2017, 04:25:40 AM »
Hey everyone.
I've just started an organic chemistry course and I'm struggling understanding the Woodward-Fieser Rules. Mainly I think it's with identifying the functional groups. I was hoping if someone could please confirm if my wavelength max was correct for my homework and any tips in general that would help.


Base value (Cyclopentenone)            =202
Double bond extending conjugation    = 30
Exocyclic double bond                      = 5
Alkyl substituents                           = (5 x 6) = 30


wavelength max                             = 267 nm




Base value (homoannular diene)        = 253
Double bond extending conjugation    = 30
Exocyclic double bond                     = (3 x 5) = 15
Alkyl substituents                           = (5 x 5) = 25


wavelength max                            = 323 nm


thank you!

Offline pgk

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Re: Woodward-Fieser Rules
« Reply #1 on: October 03, 2017, 11:24:45 AM »
Yes, it is correct according Wikipedia.
But cross-check it, from spectroscopy textbooks because some authors give different values for alkyl substituents, whether being in α, β, γ or higher position from the carbonyl group.
« Last Edit: October 03, 2017, 01:47:33 PM by pgk »

Offline sjb

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Re: Woodward-Fieser Rules
« Reply #2 on: October 03, 2017, 04:36:09 PM »
For the first isn't this a cyclohexenone? Can't remember how much difference this makes and my notes are a good distance away

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