Ether Infrared spectra

The obvious way to know a molecule is an ether is to see a C-O peak, but no C=O or O-H, since the absence of a C=O or O-H stretch confirms it is not an ester, acid, or alcohol.

The C-O stretch is found between 1000 and 1300.

Aliphalic ethers give one strong asymmetric stretch around 1120, and a very weak symmetric stretch around 850.

Aryl alkyl ethers give two bands around 1250 and 1040, symmetric and asymmetric respectively.

An example of each is below:

Dibutyl ether

Anisole

Vinyl ethers: These give a strong asymmetric stretch near 1220, and a very weak symmetric stretch near 850.

The increase in asymmetric stretch frequency of vinyl and aryl ethers compared to alkyl ethers can be explained by resonance: