Worked Examples of IUPAC Nomenclature

The clearest way to see the IUPAC system actually working is to watch a finished name come apart into its four building blocks -- prefix (with its locants), root word, primary suffix and secondary suffix -- and this section's worked-example table (numbered 11.3.1.2 in the source) does exactly that across roughly three dozen compounds. A simple branched alkane such as 3-methylpentane splits into '3-methyl' (prefix) + 'pent' (root, five carbons) + 'ane' (primary suffix, fully saturated) with no secondary suffix needed (there is no functional group beyond the hydrocarbon skeleton). Add unsaturation and the primary suffix changes to record it: 2-ethylbut-3-enoic acid is '2-ethyl' + 'but' + '3-ene' (one double bond, at C3) + 'oic acid' (secondary suffix for the carboxylic acid, the principal group that also anchored the numbering). Add a plain functional group without unsaturation and the primary suffix reverts to '-ane' while the secondary suffix records the group directly: 2-methylbutanal is '2-methyl' + 'but' + 'ane' + 'al'; hex-4-en-2-ol is (no prefix needed) + 'hex' + '4-ene' + '2-ol'. Diacids, nitriles and amides follow the identical pattern -- 2-ethyl-4-propylpentanedioic acid, 4-methylhexanenitrile, 2-methylbut-3-enamide -- and amines additionally show the N- locant convention for substituents sitting on the amine nitrogen itself rather than on the main chain (N-methylpropan-1-amine, N,N-dimethylpropan-1-amine, N-ethyl-N-methylpropan-1-amine), including the aromatic case N,N-dimethylbenzenamine, where the root word is simply 'ben …