Che 440/540 2D-NMR .
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Che 440/540 2D-NMR http://www.ch.ic.ac.uk/ectoc/echet96/papers/107/index.htm
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Transcript of Che 440/540 2D-NMR .
Che 440/540 2D-NMR
http://www.ch.ic.ac.uk/ectoc/echet96/papers/107/index.htm
Relaxation delay
90o pulse
t1 (microseconds)
90o pulse
Prototype Pulse Sequence for a 2D-NMR Experiment
Acquire (t2 seconds)
Stacked plot of 22spectra of acetone
Projection of (a)
Resulting interferogram
Origin of the Second Dimension
Fourier transform of a series of interferograms creates the second dimension.
A Simulated 1H-1H Correlated Spectroscopy (COSY) Spectrum
Actual COSY Spectrum of Isobutanol
OH
A
A BC
A, B
A
B
B,CC
COSY Spectrum of Ipsenol
HO
1
23
4
5 6 7
8
9
Basics of HETCOR and HMQC
• Heteronuclear correlated (HETCOR) and heteronuclear multiple quantum coherence (HMQC) spectroscopy show direct correlations between hydrogens and their directly bonded carbons.
• In HETCOR the signal is detected by observing 13C, and in HMQC by observing 1H. The HMQC experiment is shorter, but the pulse sequence is more complicated.
Both give the same information: one-bond 1H-13C correlations
13C chemicalshifts
1H chemicalshifts
no correlation
A simulated HMQC spectrum
HMQC Spectrum of Ipsenol
diastereotopic CH2’s
COSY Spectrum of Strychnine
