NMR spectroscopy
NMR detects nuclei (¹H, ¹³C) in a magnetic field; each environment gives a signal at a chemical shift δ (ppm) relative to TMS (δ = 0). Samples are dissolved in CDCl₃ (no ¹H signal). ¹³C NMR: number of peaks = number of carbon environments; shift identifies type (C=O 160–220; C–O 50–90; aromatic 110–160). ¹H NMR: number of peaks = H environments; integration gives the ratio of H atoms; splitting follows the n + 1 rule (n = H on neighbouring carbons): singlet, doublet, triplet, quartet. O–H/N–H peaks disappear on shaking with D₂O. Combine with IR and mass spectra to identify unknowns.
≈ 55 min