IUPAC Name Generator
Generate systematic organic names from structure rules. This guide explains what the topic is used for, the chemistry ideas behind it, and how students should approach related problems manually.
Step 1: Find the Parent Chain
The parent chain is the longest continuous carbon chain that contains the principal characteristic group, not just the longest chain in the molecule overall. Count its carbons to pick the base name: meth- for one, eth- for two, prop- for three, but- for four, and pent-, hex-, hept-, oct-, non-, dec- onward.
Students often default to whichever chain looks longest in the drawing. Check first whether the highest-priority functional group actually sits on that chain; if it does not, a shorter chain that includes it is the correct parent.
Step 2: Rank the Principal Characteristic Group
When a molecule has more than one functional group, only the highest-priority one becomes the suffix; the rest are named as prefixes. The common priority order, highest first, is carboxylic acid, ester, amide, nitrile, aldehyde, ketone, alcohol, amine, then alkene or alkyne as needed.
This ranking is why a molecule with both an alcohol and a ketone is named as an -one with a hydroxy- prefix, not the other way around: the ketone outranks the alcohol.
Step 3: Number for the Lowest Locants
Number the parent chain from whichever end gives the principal characteristic group the lowest possible locant. If that rule ties, give the lowest locants to the full substituent set, then break any remaining tie by assigning the lowest locant to the substituent that comes first alphabetically.
List substituent prefixes alphabetically in the final name, ignoring multiplying prefixes like di-, tri-, and tetra- when alphabetizing; a molecule with both a methyl and an ethyl group is written ethyl before methyl.
Worked Example
Consider a five-carbon chain with a ketone on carbon 2 and a methyl branch on carbon 3. The parent is pentane, the ketone makes it pentan-2-one, and the branch adds 3-methyl, giving 3-methylpentan-2-one. Numbering from the other end would put the ketone at carbon 4, which is higher, so the first direction is correct.
The Molecular Weight Calculator can confirm the resulting molecular formula matches what you intended once the structure is named.
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IUPAC Name Generator is an educational chemistry tool for generate systematic organic names from structure rules.
It uses standard textbook equations and atomic masses. For laboratory or clinical decisions, verify with official protocols.
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