Basic IUPAC Organic Nomenclature

Alcohols

Nomenclature	Formula	3D structure
Functional class name = alkyl alcohol e.g. ethyl alcohol Substituent suffix = -ol e.g. ethanol Substituent prefix = hydroxy-   e.g. hydroxyethane Structural unit :  alcohols contain R-OH

• The root name is based on the longest chain with the -OH attached.
• The chain is numbered so as to give the alcohol unit the lowest possible number.
  
• The alcohol suffix is appended after the hydrocarbon suffix minus the "e" : e.g.  -ane + -ol = -anol or -ene + ol = -enol.
  

Functional group is an alcohol, therefore suffix = -ol Hydrocarbon structure is an alkane therefore -ane The longest continuous chain is C2 therefore root = eth No locant is required since the -OH location is unambiguous (i.e. substitution at either carbon gives the same molecule) ethanol	CH3CH2OH
Functional group is an alcohol, therefore suffix = -ol Hydrocarbon structure is an alkane therefore -ane The longest continuous chain is C3 therefore root = prop It doesn't matter which end we number from, the alcohol group locant is 2- propan-2-ol or 2-propanol (or isopropanol)	CH3CH(OH)CH3
Functional group is an alcohol, therefore suffix = -ol Hydrocarbon structure is an alkene therefore -ene The longest continuous chain is C4 therefore root = but The first point of difference rule requires numbering from the right as drawn to make the alcohol group locant 1- Hence the alkene locant is 3- but-3-en-1-ol or 3-buten-1-ol	CH2=CHCH2CH2OH

 

©Dr. Ian Hunt, Department of Chemistry