Ethyl-2-butenoate NMR

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Ethyl-2-butenoate

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¹H-NMR proton decoupled spectrum of Ethyl-2-butenoate in CDCl₃.

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¹H-NMR proton coupled spectrum of Ethyl-2-butenoate in CDCl₃.

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¹³C-NMR proton decoupled spectrum of Ethyl-2-butenoate in CDC_l3.

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DEPT spectrum of Ethyl-2-butenoate

COSY spectra

• The information on the H that are coupling with each other is obtained by looking at the peaks inside the grid.  These peaks are usually shown in a contour type format, like height intervals on a map.
• In order to see where this information comes from, let’s consider an example shown below, the COSY of ethyl 2-butenoate Image may be NSFW.
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• First look at the peak marked A in the top left corner.  This peak indicates a coupling interaction between the H at 6.9 ppm and the H at 1.8 ppm.  This corresponds to the coupling of the CH₃ group and the adjacent H on the alkene.
• Similarly, the peak marked B indicates a coupling interaction between the H at 4.15 ppm and the H at 1.25 ppm.  This corresponds to the coupling of the CH₂ and the CH₃ in the ethyl group.
• Notice that there are a second set of equivalent peaks, also marked A and Bon the other side of the diagonal.

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(COSY spectra recorded by D. Fox, Dept of Chemistry, University of Calgary on a Bruker Advance DRX-400 spectrometer)

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HETCOR spectra

• The information on how the H are C are matched is obtained by looking at the peaks inside the grid.  Again, these peaks are usually shown in a contour type format, like height intervals on a map.
• In order to see where this information comes from, let’s consider an example shown below, the HETCOR of ethyl 2-butenoate.
• First look at the peak marked A near the middle of the grid.  This peak indicates that the H at 4.1 ppm is attached to the C at 60 ppm.  This corresponds to the -OCH₂- group.
• Similarly, the peak marked B towards the top right in the grid indicates that the H at 1.85 ppm is attached to the C at17 ppm.  Since the H is a singlet, we know that this corresponds to the CH₃- group attached to the carbonyl in the acid part of the ester and not the CH₃- group attached to the -CH₂- in the alcohol part of the ester.
• Notice that the carbonyl group from the ester has no “match” since it has no H attached in this example.

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(HETCOR spectra recorded by D. Fox, Dept of Chemistry, University of Calgary on a Bruker Advance DRX-400 spectrometer)

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