Spectroscopy Tutorial: Examples

Example 17


MW 108

Calculate the degree of unsaturation: the answer is 4. The molecule probably has an aromatic ring.

IR Spectrum

The most prominent band is the O-H stretch at 3335. Also look for aromatic bands from 1600-1585 and 1500-1400: they are present.

NMR Spectrum

The 4 protons from 6.6-7.2 ppm indicate an ortho- or meta-disubstituted aromatic ring. The phenol proton, -OH, shows up anywhere from 4-12 ppm; the singlet at 5.2 ppm indicates this proton. Since the ring is disubstituted, the singlet at 2.3 ppm of 3 hydrogens must indicate a methyl group on the ring.


Example 15 is 3-methylphenol: