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Topic: IR of Ethyl 3-phenylpropanoate  (Read 6842 times)

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Offline bobafettswife

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IR of Ethyl 3-phenylpropanoate
« on: January 20, 2014, 03:03:24 PM »
So I took an IR of a reagent Ethyl Cinnamate and the hydrogenated product Ethyl 3-phenylpropanoate I need to label the c=o stretches in each I r
The first image is Ethyl Cinnamate second is product
I am correct to say that the only peak that corresponds to the ester (c=o)in both Ir is that huge peak around 1700,s in both?

I am then asked to distinguish the reason for the witch the frequency in product Ethyl 3-phenylpropanoate is higher that ethyl cinnamate based on the most favorable resonance structures from both compounds and the fact that the single factor that determines stretching frequency in IR is molecule vibrations
i attached the  resonance the first one for each compound was given i was to find two more for ethyl cinnamate and one more for Ethyl 3-phenylpropanoate (excluding aromatic ring resonance)
I want to make sure I did the resonances right because its been a year since I have been in an O-chem course and they placed me in a higher course (I should have redone but too late now)
So based off the resonances and the fact that IR frequency is solely dependent on the vibrations I think that the product Ethyl 3-phenylpropanoate has a higher frequency because it is not as stabilized as ethyl cinnamate so the molecules have poetical to vibrate more?
What do you think ? Any input and help would be greatly appreciated
https://docs.google.com/document/d/1h4A1Jdo8RwkMfHe-CkKrWuzxLIeS7y9Vsn2S0V1SQkY/edit?usp=sharing
the link for my drawings i can't get the scan to fit sorry
FYI I was provided with the correct IR just incase since our lab took forever one of the rotovaps was broken so not all of us finished I did get the IR of both but i posted the one my TA provided
« Last Edit: January 20, 2014, 03:30:20 PM by bobafettswife »

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