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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 l
abelled (*) would probably all be named as alkyl alkyl ethers.

"Simple" ethers
  • 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
  • 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

  • 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 *
CH3OC(CH3)3  
* In reality, these examples are simple enough that they would typically be named as alkyl alkyl ethers




organic chemistry ©Dr. Ian Hunt, Department of Chemistry University of Calgary