IR Spectroscopy Tutorial: Esters
The carbonyl stretch C=O of aliphatic esters appears from 1750-1735 cm-1; that of α, β-unsaturated esters appears from 1730-1715 cm-1. See also:
The CO stretches appear as two or more bands in the region 1300-1000 cm-1.
The spectra of ethyl acetate and ethyl benzoate are shown below. Note that the C=O stretch of ethyl acetate (1752) is at a higher wavelength than that of the α, β-unsaturated ester ethyl benzoate (1726). Also note the CO stretches in the region 1300-1000 cm-1.
- C=O stretch
- aliphatic from 1750-1735 cm-1
- α, β-unsaturated from 1730-1715 cm-1
- CO stretch from 1300-1000 cm-1