Predict ¹H and ¹³C NMR chemical shifts for structure elucidation
¹H NMR: 0-13 ppm range, TMS reference at 0 ppm
¹³C NMR: 0-220 ppm range, broader distribution than ¹H
Deshielding: EWG, π-bonds, aromatics cause downfield shift (higher ppm)
Multiplicity: n+1 rule for ¹H NMR (n = # of equivalent neighboring H)
Integration: Area under ¹H peak proportional to # of protons
Nuclear Magnetic Resonance (NMR) chemical shift is the resonant frequency of a nucleus relative to a standard (usually tetramethylsilane, TMS). Chemical shifts provide crucial information about the electronic environment of nuclei, enabling structure determination and functional group identification.
¹H NMR chemical shifts typically range from 0-13 ppm, while ¹³C NMR shifts span 0-220 ppm. Deshielding effects from electronegative atoms, π-bonds, and aromatic rings cause downfield shifts (higher ppm values). Understanding these patterns is essential for organic structure elucidation and compound characterization.