locant

chemical nomenclature

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Last updated

June 30, 2026

Quick Summary

A locant is a part of a chemical name that shows where an atom or group is located within a molecule. For example, in the chemical name m-xylene, the 'm-' is a locant indicating the position of the methyl groups. Other examples include 'β-' in β-naphthylamine and '2-' in 2-butanol. The term "locant" is derived from "location".1

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hydrocarbon
Nomenclature
…a number (3-), called a locant, obtained by successively numbering the carbons in the parent chain starting at the end nearer the branch. The compound is therefore called 3-methylheptane.
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…a number (3-), called a locant, obtained by successively numbering the carbons in the parent chain starting at the end nearer the branch. The compound is therefore called 3-methylheptane.
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steroid
Steroid numbering system and nomenclature
…and suffixes include numbers, called locants, indicative of the position in the carbon skeleton at which the modification occurs, and, where necessary, the orientation of a substituent is shown as α- or β-. The carbon atom at position 3, for example, is referred to as C3; a hydroxyl group attached…
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…and suffixes include numbers, called locants, indicative of the position in the carbon skeleton at which the modification occurs, and, where necessary, the orientation of a substituent is shown as α- or β-. The carbon atom at position 3, for example, is referred to as C3; a hydroxyl group attached…
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