IUPAC naming of organic compounds – parent chain, numbering, prefixes and suffixes
ChemistryOrganic ChemistryAges 16–17
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Name branched and functionalised open-chain molecules step by step from their skeletal formulas: find the principal characteristic group that gives the suffix, choose the parent chain, number it and put the prefixes in alphabetical order, with every step checked. A quiz, an editor that names any molecule you draw, a reverse mode that asks you to draw the structure for a given name and a panel of functional group isomers complete the trainer.
Lesson: Organic chemistry: IUPAC nomenclature of aliphatic compounds and functional group isomerism
What it shows
An IUPAC name is built in a fixed order. The most senior characteristic group gives the suffix (carboxylic acid > ester > amide > nitrile > aldehyde > ketone > alcohol > amine); halogens, nitro groups and alkyl branches are only prefixes. The parent chain carries the most principal groups and, under the 2013 recommendations, is the longest chain; it is numbered so that the suffix, then the multiple bonds, then the prefixes get the lowest locants, and the prefixes are cited in alphabetical order. Pairs such as propanal and propanone show that one molecular formula can belong to different classes.
How to use
In Name it, choose the suffix, tap the carbons of the parent chain, tap the carbon that gets locant 1 and tap the prefixes in alphabetical order, pressing Check after each step; Show me reveals a step. Quiz asks you to pick the correct name. In Draw, build a molecule with the tools and read its name; From name asks you to draw a named molecule and press Check structure. Isomers compares compounds with one formula.
Parameters you can change
- Screen Name it (step by step), Quiz, Draw and name, Draw from a name, Functional group isomers
- Starting molecule 2-methylbutane, 2,2-dimethylbutane, 3-ethyl-2-methylpentane, 2,3,4-trimethylpentane, 5-ethyl-2-methylheptane, but-2-ene, 2-methylbut-2-ene, 3-methylbut-1-ene, buta-1,3-diene, 4-methylpent-2-yne, 2-chloropropane, 2-bromo-2-methylpropane, 1,2-dichloroethane, 1-bromo-3-chloropropane, 2-nitropropane, trichloromethane, propan-2-ol, 2-methylpropan-2-ol, 3-methylbutan-2-ol, 2-ethylbutan-1-ol, ethane-1,2-diol, but-3-en-2-ol, propanal, 2-methylpropanal, butan-2-one, pentan-3-one, 4-methylpent-3-en-2-one, 4-hydroxybutan-2-one, propanoic acid, 2-methylpropanoic acid, 3-chlorobutanoic acid, but-2-enoic acid, butanedioic acid, 2-aminopropanoic acid, methyl ethanoate, ethyl propanoate, propanamide, propanenitrile, propan-1-amine
- Quiz molecules All, Hydrocarbons, halogen and nitro compounds, Characteristic groups
- Isomer set (molecular formula) C₂H₆O, C₃H₆O, C₃H₆O₂, C₄H₁₀O, C₄H₈O₂
Questions to explore
- Why is 2-ethylbutane not a correct name, and what is the correct one?
- In 4-hydroxybutan-2-one, why is the OH group a prefix rather than the suffix?
- Why does ethyl come before dimethyl in 4-ethyl-2,3-dimethylhexane?
