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Topic: Help Interpreting HNMR Data!  (Read 2443 times)

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Offline danimal

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Help Interpreting HNMR Data!
« on: August 07, 2014, 12:07:00 AM »
I'm working on my thesis and I need some help interpreting some HNMR data that I've gathered. Here are some specs to help:

JOEL 400 MHz HNMR
Solvent: CDCl2
Mixture: I am hoping that it is a butyl ester with a long palmitate chain on the non -OCH2 side.

Problem: I need help differentiating this result from a sample of pure olive oil and why they are different. Please *delete me* I am stuck. If you need the peak and height tables, I can provide them.

Sample 1 - This should be the butyl ester part with the long chain.
http://imgur.com/YQrF9jB
Sample 2 - This should be pure olive oil
http://imgur.com/5w4YTzp

The paper that may help that I have been using is here: http://www.virtualmaze.co.in/sample/Biofuels%20Info/BioFuels/From_Veg_oil_method.pdf

And the specific part that may help with the analysis (but I don't understand what the guy is saying)
However,
the simplest method is by applying a simple equation, relating
the normalized integral of the signal due to the R-acyl
methylenic protons in soybean oil plus alkyl esters (2.2–2.4 ppm)
and the integral of the singlet due to the protons on the OCH3
group in biodiesel (3.6–3.7 ppm). When moving from methanol
to ethanol a problem arises due to a superimposition of the
glyceryl methylenic hydrogens in soybean oil and the -OCH2
group in the ethyl ester biodiesel product. While this problem
has been overcome by a number of methods,24 it concerned us
when thinking about quantifying our conversion with butanol
by applying NMR spectroscopy. However, fortunately, in the
case of butobiodiesel, the triplet due to the -OCH2 group in the
butyl ester chain is centered at 4.05 ppm and the signals due to
the glyceryl methylenic hydrogens in soybean oil start at 4.10
ppm. Using a 300 MHz spectrometer, it is possible to integrate
the butyl ester triplet without incorporating part of the oil signal
and so the same equation can be used for butobiodiesel as for
regular biodiesel, the only change being the normalization factor.

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