Thioethers

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Basic IUPAC Organic Nomenclature

Thioethers or sulfides

Nomenclature	Formula	3D structure
Functional class name = alkyl alkyl sulfide e.g. ethyl methyl sulfide Substituent suffix = sulfide Substituent prefix = alkylthio- e.g. methylthioethane Substitutive = -thio- Structural unit : thioethers contain R-S-R

Thioethers are named in much the same way as their oxygen cousins, ethers.

"Simple" thioethers

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

Functional group is a simple thioether, therefore use alkyl alkyl sulfide First substituent is C1 alkane therefore alkyl = methyl Second substituent is C2 alkane therefore alkyl = ethyl ethyl methyl sulfide	CH₃CH₂SCH₃
Functional group is a simple thioether, therefore use alkyl alkyl sulfide Both substituents are C1 alkane therefore alkyl = methyl Since there are two alkyl groups, multipler = di dimethyl sulfide	CH₃SCH₃

"Intermediate" thioethers

If one of the groups is more complex then the thioether group is usually treated as an alkylthio- (i.e. R-S-) substituent.
The more complex group (i.e. longer chain, more branched, other substituents) defines the root.

Hydrocarbon structure is an alkane therefore -ane
The longest continuous chain is C3 therefore root = prop
Substituent is C1 alkane therefore alkyl = methyl
The first point of difference rule requires numbering from the right as drawn to make the group locant 1-

1-methylthiopropane

CH₃CH₂CH₂SCH₃

"Complex" thioethers

If both groups are complex then the ether can be named using -thio

Hydrocarbon structure is an alkane therefore -ane
Functional group is an thioether, therefore prefix = -thio-
The longest continuous chain (including the S) is 5 therefore root = pent
Numbering from the left as drawn to make the thio group locant 2-

2-thiopentane

CH₃SCH₂CH₂CH₃

©Dr. Ian Hunt, Department of Chemistry