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#1 2009-03-16 16:24:20

orgopete
Administrator

Identify ethyl isobutyrate from IR and NMR spectra

Yahoo!Answers in chemistry wrote:

Open Question: Organic Chemistry Synthesis Products and IR help please!!!! Check my work?
Can someone please check my work? I am so confused about all of this stuff! :(

http://www.curvedarrow.com/chem/ZZ77893F59.jpg
Which functional groups do you see on the spectrum?
alkyne, alkene, benzene, ester, ether, aldehyde, alcohol, nitrile

I see: alkene, alcohol

What is the compound?
http://www.curvedarrow.com/chem/ZZ4884E84A.jpg
A?

Obviously, the questioner is lost. A is neither an alkene or an alcohol, his answer above.
Let's analyze what we have.
From the IR, we have a C=O by the big peak around 1700 cm-1. There is a C-O peak, but it isn't necessary.

From the NMR, we know C6H12 contains a ring or double bond. The C=O is that double bond.

The peak at 4 ppm is a carbon connected to an oxygen and it is a CH2 from the integral. The adjacency rule says that if it has 4 peaks, then N + 1 means there are 3 hydrogens adjacent.

That gives us a -OCH2CH3. It also means the peak at 1.3 ppm, 3H, triplet is the CH3.

The peak at 1.0 ppm, 6H, doublet must be two CH3 groups and they are connect to a CH. The peak at 2.3 ppm, multiplet, 1H must be the CH. That gives us a -CH(CH3)2

Okay, let's put this together, a CH3CH2O- plus a C=O plus a -CH(CH3)2. I get CH3CH2OCOCH(CH3)2, J.

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