[U. of Ottawa NMR Facility Blog] Isotope Effects and the 19F - 13C HMQC Spectrum of Trifluoroacetic Acid
Isotope Effects and the 19F - 13C HMQC Spectrum of Trifluoroacetic Acid
The 19F - 13C HMQC spectrum of trifluoroacetic acid is shown in the figure below.
http://4.bp.blogspot.com/-roN1Zav9lO8/UIWplTlt8WI/AAAAAAAAA-o/G0N2j7vkqns/s400/tfa1.jpg
The data were collected with a delay appropriate for a 19F - 13C J coupling constant between the 1JF-C coupling constant of 284 Hz and the 2JF-C coupling constant of 44 Hz. The top and side traces are the one-pulse 19F and 13C spectra, respectively. Why are the HMQC responses not at the same 19F chemical shift and why aren't they correlated...
nmrlearner
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10-22-2012 09:07 PM
[U. of Ottawa NMR Facility Blog] The Scale on an NMR Spectrum
The Scale on an NMR Spectrum
Some people new to NMR spectroscopy have trouble with the meaning on the scales of their NMR spectra. Usually the data are plotted with a chemical shift scale (?). This scale increases to the left and is usually reported in units of parts per million (ppm). The chemical shift of a resonance in a sample, ?sample , in ppm is defined as follows:http://3.bp.blogspot.com/_5wBTR2kKTqA/S41bCRKGJzI/AAAAAAAAAv0/ewNylq_3g6I/s400/chemical_shift.jpgwhere ?sample is the absolute frequency of the sample resonance and ?reference is the absolute frequency of an agreed upon...
nmrlearner
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08-21-2010 08:15 PM
A question about NMR spectroscopy delta?
How do I find the delta for hydrogens? For example, a peak is between 7 and 8. How do I find the exact chemical shift delta?I searched everywhere on how to calculate it but I don't get the same delta of 7.39.