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Nomenclature Summary / Group Priority

This section contains the basic IUPAC rules for nomenclature and a table of functional groups in priority order, with examples.

Naming branched chain alkanes (the IUPAC way....)

  • Find the parent hydrocarbon. This is based on the longest continuous carbon chain. If there are chains of equivalent length, then select the one with the most branch points as the parent.
  • Number the atoms in the parent chain, beginning at the end nearer the first branch point. If there is branching an equal distance from both ends, then consider the next branch point (repeat as required).
  • Identify and number the substituents. Remember there must be as many numbers as there as substitutents.
  • Write out the name as a single word, using hyphens to separate the different prefixes and commas to separate the numbers. If two or more different substitutents are present, cite them in alphabetical order. With identical substituents, use the prefix di-, tri-, tetra- etc. as required. Ignore these prefixes when alphabetising.
  • If a substituent has subranching (ie. its complex) then reapply the first 4 steps as if it were a compound. Numbering must begin at the point of attachment. Now set this substituent in parentheses.
Naming the parent chain:

Here is a list of the root names for the hydrocarbon chains of C1 to C12 and a few other biologically important chains:

  • C1 = meth-
  • C2 = eth-
  • C3 = prop-
  • C4 = but-
  • C5 = pent-
  • C6 = hex-
  • C7 = hept-
  • C8 = oct-
  • C9 = non-
  • C10 = dec-
  • C11 = undec-
  • C12 = dodec-
  • C16 = hexadec-
  • C18 = octadec-
  • C20 = icos-
Functional Groups and Priorities:

Here is a list of important functional groups arranged in decreasing priority order. All the structures can be manipulated using CHIME.
 

Functional
Group
Formula
Suffix
Prefix
Structure
Name
Cations -ammonium
-phosphoium
-sulphonium
ammonio-
phosphonio-
sulphonio-
Trimethylammonium
Carboxylic Acids -oic acid carboxy- Propanoic acid
Acid Anhydrides -oic anhydride
----- 
Ethanoic anhydride
Esters alkyl -oate alkoxycarbonyl-
carbalkoxy-
Methyl propanoate
Acyl Halides -oyl halide haloalkanoyl- Propanoyl chloride
Amides -amide carbamoyl- Ethanamide
Nitriles -nitrile
-onitrile
cyano- Propionitrile
Aldehydes -al alkanoyl- Propanal
Ketones -one -oxo- Propanone
Alcohols -ol hydroxy- Propanol
Thiols -thiol mercapto- Propanethiol
Amines -amine amino-
aza-
Propylamine
Ethers - ether -oxa-
alkoxy-
Dimethyl ether
Sulphides - sulphide -alkylthio
thia
Dimethyl sulphide
Alkenes -ene alkenyl- Propene
Alkynes -yne alkynyl- Propyne
Halides -halide halo- Bromopropane 

Propyl bromide

Nitro
----- 
nitro- Nitropropane
Alkanes -ane alkyl Propane


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

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