Spectroscopy Tutorial: Alcohols

IR Spectroscopy

Alcohols have characteristic IR absorptions associated with the O-H and the C-O stretching vibrations. When run as a thin liquid film, the O-H stretch appears in the region 3500-3200 cm-1 and is a very intense, broad band. The C-O stretching vibration appears from 1260-1050; this band is not nearly as characteristic as the O-H band and is in a region that is characteristic of a lot of other functional groups.

NMR Spectroscopy

The hydrogen on the hydroxyl group appears from 2-4 ppm (depending on the concentration of the sample). This proton is rarely split. The hydrogen on the carbon adjacent to the hydroxyl group will be at 3.4-4 ppm. Remember, normal “alkyl” protons are from 0-2 ppm.


Example 3