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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: toadesque on December 13, 2009, 06:53:58 PM

Title: Quick question regarding IR spectras
Post by: toadesque on December 13, 2009, 06:53:58 PM
It's asking me how you could distinguish between the 2 compounds by using infrared spectroscopy

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fimg29.imageshack.us%2Fimg29%2F7479%2Ffefhy.jpg&hash=8015e26d1604e16ec41c1103dd70f4bea7f7565b)

sorry i know it's a terrible pic, made it quickly.

I don't really see how the groups are different? The double bond is in a different location on the 2nd one but what does that tell you?
Title: Re: Quick question regarding IR spectras
Post by: 408 on December 13, 2009, 08:24:56 PM
Draw resonance forms.  How would that affect a given IR stretch?
Title: Re: Quick question regarding IR spectras
Post by: orgopete on December 13, 2009, 09:41:45 PM
The resonance structure suggestion can help identify which structure or the amount of single bond character (a weaker bond than a double bond) a compound may have.
Title: Re: Quick question regarding IR spectras
Post by: bromidewind on December 16, 2009, 09:09:59 PM
Look at the hybridizations of the C=O and the C=C on the first one. They are different than the second one. Hybridization peaks are fairly easy to see on IR spec.