IUPAC Nomenclature
IUPAC nomenclature is the systematic method for naming chemical compounds, developed and maintained by the International Union of Pure and Applied Chemistry (IUPAC). For organic compounds, it provides an unambiguous, internationally recognised name based on the longest carbon chain (parent chain), substituents, and functional groups, enabling chemists worldwide to communicate compound structures without ambiguity. The rules cover alkanes, alkenes, alkynes, halides, alcohols, carboxylic acids, and all other organic functional groups.
IUPAC Naming Rules for Common Organic Functional Groups
| Functional Group | IUPAC Suffix/Prefix | Example Formula | IUPAC Name | Common Name |
|---|---|---|---|---|
| Alkane (C–C only) | -ane | C4H10 | Butane | n-Butane |
| Alkene (C=C) | -ene | C3H6 | Propene | Propylene |
| Alkyne (C≡C) | -yne | C2H2 | Ethyne | Acetylene |
| Alcohol (–OH) | -ol | C2H5OH | Ethanol | Ethyl alcohol |
| Carboxylic acid (–COOH) | -oic acid | CH3COOH | Ethanoic acid | Acetic acid |
| Ketone (C=O, internal) | -one | CH3COCH3 | Propan-2-one | Acetone |
Interactive Tools
Khan Academy — IUPAC Naming
Step-by-step videos on naming alkanes, alkenes, and functional groups.
Open ToolChemSpider — IUPAC Name Search
Search chemical structures by IUPAC name or draw structure to get IUPAC name.
Open ToolIUPAC — 2013 Recommendations (Blue Book)
Official IUPAC recommendations for organic nomenclature.
Open Tool
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Related Terms
Constitutional Isomer
Constitutional isomers (also called structural isomers) are molecules that share the same molecular formula but differ in the connectivity of their atoms — that is, in which atoms are bonded to which. They are distinct compounds with different physical and chemical properties, such as boiling point, melting point, and reactivity. Constitutional isomerism is the most basic form of isomerism and is distinct from stereoisomerism, where connectivity is the same but spatial arrangement differs.
Polymer
A polymer is a large macromolecule composed of many repeating structural units called monomers, linked together by covalent bonds through a process called polymerisation. Polymers can be natural (e.g., cellulose, proteins, DNA) or synthetic (e.g., polyethylene, nylon, PVC), and their physical properties are governed by chain length, branching, cross-linking, and monomer identity. They are indispensable in modern industry, biology, and materials science.
Amino Acid
An amino acid is an organic molecule that contains both an amino group (–NH2) and a carboxyl group (–COOH) attached to the same central (alpha) carbon, along with a variable side chain (R group) that determines the identity and properties of each amino acid. There are 20 standard amino acids encoded by the genetic code that serve as the building blocks of proteins. Amino acids differ in polarity, charge, size, and chemical reactivity, which directly determines protein structure and function.
IUPAC stands for International Union of Pure and Applied Chemistry, founded in 1919. 'Nomenclature' derives from Latin 'nomen' (name) + 'calare' (to call). Systematic organic naming rules were first formalised at the Geneva Congress of 1892 and were greatly expanded in the 1957 (IUPAC) and 2013 Blue Book recommendations.