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CHEM 262 - NMR
Chemical shift values for common proton chemical environments.
Chemical Environment | Chemical Shift |
---|---|
alkyl group protons | 0.9 ppm - 1.8 ppm (chemical shift increases w/ sterics) |
geminal halide protons | 2.8 ppm - 4.2 ppm (inductive effect falls off w/ distance; directly proportional to electronegativity) |
carboxylic acid protons | 11.0 ppm - 12.0 ppm (due to resonance effect and inductive effect) |
benzene protons | 7.2 ppm (delocalized electrons circulate and produce a constructive magnetic field) |
benzyllic protons | 2.0 ppm - 2.5 ppm (anisotropy effect falls off w/ distance) |
olefin protons | 5.0 ppm - 6.0 ppm (delocalized electrons circulate and produce a constructive magnetic field) |
acetylene protons | 2.0 ppm (delocalized electrons circulate and produce a deconstructive magnetic field) |
hydroxyl protons | special case (chemical shift depends on concentration b/c of H-bonding) |