An IUPAC name is an instruction for drawing the molecule: how long the chain is, what is attached and where. Learn the stems, suffixes and prefixes and you can go from name to structure and back.
Find the longest carbon chain containing the functional group; its length gives the stem (meth-, eth-, prop-, but-, pent-, hex-). The functional group gives the suffix (-ane, -ene, -ol, -al, -one, -oic acid, -nitrile, -amine) or a prefix (chloro-, bromo-, methyl-). Number the chain from the end that gives the lowest locants, list prefixes alphabetically, and use di-, tri- for repeats.
Draw molecules in the naming simulator and check your name against the generated one. Start simple, then add branches and functional groups.
| Compound | Name | Rule shown |
|---|---|---|
| CH3CH(CH3)CH2CH3 | 2-methylbutane | number to give the branch the lowest locant |
| C(CH3)4 | 2,2-dimethylpropane | di- and a locant for each group |
| CH3CH=CHCH3 | but-2-ene | locant for the C=C |
| CH3CHClCH3 | 2-chloropropane | halogen as a prefix |
| CH3CH(OH)CH3 | propan-2-ol | -ol with locant |
| CH3CH2CH2CHO | butanal | -al; C1 is always the CHO carbon |
| CH3COCH2CH3 | butanone | -one |
| CH3CH2COOH | propanoic acid | COOH carbon counted in the chain |
| CH3COOCH3 | methyl ethanoate | alkyl (from alcohol) + -oate (from acid) |
| CH3CH2CN | propanenitrile | CN carbon counted in the chain |
| CH3CH2NH2 | ethylamine (ethanamine) | -amine |
Always find the longest chain, which may bend round a corner in a drawn structure; a “branch” at the end of a chain is just part of the chain. Number from the end that gives the lowest locants, and in nitriles, acids and aldehydes the functional-group carbon is C1 and is included in the stem count.
Four quick checks. Each correct answer earns XP and records this skill on your profile.
What is the name of CH3CH2CH2OH?
What is the name of CH3CH2CHO?
What is the name of CH3COOCH2CH3?
What is the correct name for CH3CHBrCH2CH3?
Unlocks once the four checks above are done. Worth more XP, written to AS Paper 1 and Paper 2 standard.
What is the IUPAC name of (CH3)2CHCH2CH2CH3?
Which is the correct structure of 2,3-dichlorobutane?
What is the name of CH3CH2CH2CN?
Which name is correct for CH2=CHCH(CH3)CH3?
This skill is now recorded on your profile. Keep the chain going.