Spectroscopy Tutorial: Amines

IR Spectroscopy

Primary and secondary amines show N–H stretches in the region 3300-3000. These are weaker bands than the alcohol O–H stretches which appear in the same region. If it is a primary amine (–NH2) there are two bands in this region; if it is a secondary amine (–NHR) there is one band; if it is a tertiary amine (-NR2) there are no bands in this region. You can also look for C-N stretch bands, although these appear in regions that show bands for othe functional groups as well.

NMR Spectroscopy

The amine proton(s) show(s) as a broad peak (but not as broad as a carboxylic acid proton peak) from 0.5–3.0 ppm if the amine is aliphatic; 3–5 ppm if the amine is aromatic. The proton on a carbon adjacent to the amine group is found from 1.5–2 ppm.
IR:Examples: 2-Ethylaniline (11) and diisopropylamine (12).


Example 11

Example 12