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#1 2009-09-23 19:51:16

orgopete
Administrator

Identify butyl acetate IR and NMR spectra

Yahoo!Answers in chemistry wrote:

I have an unknown organic compound which I extracted, purified, and tested in lab. I spent 6 hours with my data and the CRC handbook, only to get what my lab TA decided was "wrong but almost close." I would like some advice on determining this compound. Here is my data,

It is a clear liquid.
It smells like nail polish.
It dissolved in the organic layer, not aqueous.
It has a b.p. range of 124.5-129.5 degrees C.
It is a neutral compound, neither an acid or base.
C13 NMR revealed 6 peaks:
170.53
63.82
30.34
20.41
18.77
13.25

HNMR revealed 5 peaks (Integration #, Splitting, Shifting):
3, Triplet, 0.77
2, Sextet, 1.22
2, Quintet, 1.46
3, Singlet, 1.86
2, Triplet, 3.90

IR Spectrometry revealed peaks (transmittance in cm-1):
~3500, broad
~2960, moderately broad
1747, moderately sharp
1460, sharp
1360, sharp
~1250, moderately sharp
~1030, moderately sharp
950, weak-sharp
633, weak-sharp
606, weak-sharp

I determined the compound to be 2-Hexanone (Butyl methyl ketone), and, as I stated previously, I was told it is close but not right. I would appreciate ANY help you can give. I do not know the molecular formula, so I'm not sure if there are any halogens or if the oxygen I guess is actually a nitrogen. I would love any hints. My lab report isn't due until next Wednesday, but I am really frustrated by this and would love to get it finished. Please help. Thank you.

Let me collect the minimum of facts.
C13 NMR peak at 170 ppm, an ester, not a ketone, and it has six carbons
IR 1747 cm-1 consistent with an ester
1H-NMR
2 x CH3, 3 x CH2, therefore linear, no branching.
3H singlet at 1.85 ppm, therefore not connected to an oxygen atom. It must be a CH3C=O
2H triplet at 3.90 ppm, connected to an oxygen atom and CH2 adjacent
Of the six carbons, only five have hydrogen attached to them

Really, do we need more to ID this?
CH3CO2CH2CH2CH2CH3

Some of the other data may not be helpful. The broad bands in the IR, I ignored as they wouldn't agree with an authentic sample.

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