Mixed ethers :
ether in which the radicals united to oxygen are different.
IUPAC nomenclature :
The smaller, shorter alkyl group becomes the alkoxy substituent. The larger, longer alkyl group side becomes the alkane base name. Each alkyl group on each side of the oxygen is numbered separately. The numbering priority is given to the carbon closest to the oxgen. The alkoxy side (shorter side) has an "-oxy" ending with its corresponding alkyl group.
For example, CH3CH2CH2CH2CH2-O-CH2CH2CH3 is
1-propoxypentane