Data reference—Proton and carbon-13 NMR chemical shifts

¹H and ¹³C chemical-shift ranges indicate the electronic environment around each nucleus. Use them with signal count, integration and splitting (for ¹H) to test a structure rather than assigning a peak from shift alone.

Electronegative atoms, carbonyls and aromatic π systems deshield nearby nuclei and move signals downfield. Compare every predicted environment with the spectrum and total atom count.

A proton next to oxygen appears downfield from a simple alkyl proton; a carbonyl carbon appears in a distinct downfield ¹³C region, supporting an aldehyde, ketone, acid or ester assignment.

Shift ranges overlap and depend on solvent and conditions; one peak position cannot uniquely prove a structure.