Ethers

Basic IUPAC Organic Nomenclature

Ethers

Nomenclature	Formula	3D structure
Functional class name = alkyl alkyl ether e.g. ethyl methyl ether Substituent prefix = alkoxy- e.g. methoxyethane

Examples of how each of the types of nomenclature are applied are given below. No one method is more correct than the other, but some guidance on the common practices is given.

Note : the examples chosen are to illustrate the naming subsystem.

In practice, the examples labelled (*) would probably all be named as alkyl alkyl ethers.

"Simple" ethers

If both groups are simple alkyl groups, then the ether is usually named as alkyl alkyl ether
The alkyl groups are listed in alphabetical order
If the two alkyl groups are the same, then it's a dialkyl ether

Functional group is a simple ether, therefore use alkyl alkyl ether
First substituent is C1 alkane therefore alkyl = methyl
Second substituent is C2 alkane therefore alkyl = ethyl

ethyl methyl ether

CH₃CH₂OCH₃

Functional group is a simple ether, therefore use alkyl alkyl ether
Both substituents are C2 alkane therefore alkyl = ethyl
Since there are two alkyl groups, multipler = di

diethyl ether

CH₃CH₂OCH₂CH₃

"Intermediate" ethers

If one of the groups is more complex then the ether group is usually treated as an alkoxy substituent (i.e. R-O-).
The ether is treated as a substituent (i.e. it is not the principal functional group).
The more complex group (i.e. longer chain, principal functional group, more branched, other substituents) defines the root.

Hydrocarbon structure is an alkane therefore -ane The longest continuous chain is C3 therefore root = prop Ether substituent is a C1 alkoxy = methoxy The first point of difference rule requires numbering from the right as drawn to make the group locant 1- 1-methoxypropane *	CH₃CH₂CH₂OCH₃
Hydrocarbon structure is an alkane therefore -ane The longest continuous chain is C3 therefore root = prop Ether substituent is a C1 alkoxy = methoxy Numbering makes the group locant 2- 2-methoxypropane *	CH₃CH(OCH₃)CH₃
Functional group is an alkene therefore suffix = -ene The longest continuous chain is C4 therefore root = but The C=C is the principal functional group and needs the lowest locant The C=C is between C1 and C2 so the locant is 1- Ether substituent is a C1 alkoxy = methoxy Numbering makes the alkoxy group locant 4- 4-methoxybut-1-ene	CH₃OCH₂CH₂CH=CH₂
* In reality, these examples are simple enough that they would typically be named as alkyl alkyl ethers

"Complex" ethers

If both groups are complex then the ether can be named using -oxa which treats the oxygen as a substituent in the chain.
The ether is treated as a substituent (i.e. it is not the principal functional group).

Hydrocarbon structure is an alkane therefore -ane
Ether is treated as a chain substituent, therefore prefix = -oxa-
The longest continuous chain (including the O) is 5 therefore root = pent
Numbering from the left as drawn to make the oxa group locant 2-

2-oxapentane *

CH₃OCH₂CH₂CH₃

Hydrocarbon structure is an alkane therefore -ane
Ether is treated as a chain substituent, therefore prefix = -oxa-
The longest continuous chain (including the O) is 4 therefore root = but
The substituents are C1 alkyl groups i.e. methyl groups
There are two methyl groups i.e. dimethyl
The first point of difference rule requires numbering from the right as drawn to make the methyl group locants 2,2- and the oxa locant 3- (i.e. 2,2,3- is preferred to 2,3,3-)

2,2-dimethyl-3-oxabutane *

ether

CH₃OC(CH₃)₃

* In reality, these examples are simple enough that they would typically be named as alkyl alkyl ethers