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NMR N uclear M agnetic R esonance. Proton NMR (and other nuclei): Conformational exchange. Index. NMR-basics. H-NMR. NMR-Symmetry. Heteronuclear-NMR. Dynamic-NMR. Chemical Equivalence by Interconversion. Equivalence in Shift Depends on Temperature, Solvent, Catalyst….
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NMRNuclear Magnetic Resonance ProtonNMR (and other nuclei): Conformational exchange Index NMR-basics H-NMR NMR-Symmetry Heteronuclear-NMR Dynamic-NMR
Chemical Equivalence by Interconversion Equivalence in Shift Depends on Temperature, Solvent, Catalyst… • Keto-Enol Interconversion • Restricted Rotation (amides) • Rings InterconversionAxial H -> equatorial H Rapid at room temperature, Slow at –60C
Keto-Enol Interconversion CH3 CH2 =CH =CH Keto CH2 OH enol
Keto-Enol Interconversion =CH CH3 Keto CH2 enol Keto
Ring Interconversion C-NMR 30oC Cis-1,4-dimethylcyclohexane -60oC
Exchange : DNMR – Dynamic NMR NMR is a convenient way to study rate of reactions – provided that the lifetime of participating species are comparable to NMR time scale (10-5 s) At low temperature, hydrogens form an A2B2X spin system At higher temperature germanium hop from one C to the next
Index NMR-basics H-NMR NMR-Symmetry Heteronuclear-NMR Dynamic-NMR NMR and Organometallic compounds