Deep-Dive Guides · IUPAC Nomenclature

IUPAC Nomenclature — the complete deep dive

Naming is not vocabulary, it is an algorithm: find the senior characteristic group, choose the parent hydride that carries it, number to the rules in their fixed order, cite everything else as a prefix, and assemble. Run the algorithm in that order and every name falls out, including the ones that look impossible.

Free extract — the opening section of the guide, in full.

0. How to use this guide — the naming algorithm

Every systematic name is built in the same five moves. Do them in this order and in no other; most wrong answers come from numbering before the parent has been settled, or from letting a substituent prefix decide the numbering when a suffix was present all along.

1Find the senior characteristic groupit alone decides the suffix2Choose the parent hydride that carries itthe group outranks chain length3Number the parentsuffix first, then unsaturation, then prefixes4Cite everything else as a prefixalphabetical, multiplying prefixes ignored5Assemble: prefixes + parent + unsaturation + suffixlocants next to what they cite
The order is not advisory. Steps 1 and 2 fix what the name is about; step 3 can only be decided once they are settled.
The three questions to ask of any naming problem: (1) Which characteristic groups are present, and which is senior? Only the senior one becomes the suffix; every other becomes a prefix. (2) Does the parent have to contain that group? Yes — the parent chain or ring must include the carbon bearing the principal characteristic group, even if a longer chain exists elsewhere. (3) Have I applied the numbering rules in IUPAC's order? Principal characteristic group, then skeletal unsaturation, then detachable prefixes, then first point of difference, then alphabetical order.

Read the rest of this guide

The remaining 10 sections — Step 1: the senior characteristic group, Step 2: choosing the parent hydride, Step 3: numbering, and the tie-breaks in order, Step 4: prefixes, multiplying prefixes and alphabetisation and more — are part of ChemVidya Full Access, along with the other guides, the books, the study notes and 6,000+ practice questions with worked solutions.

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