Spectroscopy Reference
Characteristic IR bands and ¹H/¹³C NMR shifts indexed by functional group.
How to use this tool
Look up the characteristic IR absorption or ¹H NMR chemical shift for a functional group, a first-pass aid for working out what's in a spectrum, or for predicting where a group should appear.
What to enter
- Tab: IR (cm⁻¹) for infrared bands, or ¹H NMR (ppm) for proton chemical shifts.
- Filter by group or value: type a group name or a number to narrow the table (e.g. ketone, nitrile, 1705). Leave it blank to see the whole table.
Reading the result
IR mode lists the bond/group, band position in cm⁻¹, intensity and notes; NMR mode lists the proton environment, δ in ppm, multiplicity and notes. Treat these as starting points, real positions shift with solvent, concentration and neighbouring groups, so confirm against an authentic standard.
Worked example
On the IR tab, type ketone to pull up the C=O stretch at 1725–1705 cm⁻¹ (strong), the band you'd look for to confirm a ketone.
How to read this
IR bands are given in wavenumbers (cm⁻¹) with typical intensity. ¹H NMR shifts are approximate chemical shifts (δ, ppm) versus TMS in CDCl₃; real shifts move with solvent, concentration and neighbouring groups. Use these as a first-pass assignment aid, then confirm against authentic standards.
Sources
- Pavia, Introduction to Spectroscopy, 5th ed. (correlation tables).
- SDBS (AIST) reference spectra; Sigma-Aldrich IR/NMR correlation charts.