Lab and analysis
InChIKey
Definition
A fixed length 27 character hashed form of the InChI, used to search and link chemical records, for example LFQSCWFLJHTTHZ-UHFFFAOYSA-N for ethanol.
An InChIKey has three blocks separated by hyphens: 14 characters for the molecular skeleton, 10 characters for stereochemistry, isotopes and version flags, and one character for protonation.
Because it is short and fixed length, the InChIKey is ideal for exact structure lookup across databases. Stereoisomers share the first block, which makes it easy to find related forms. CompoundList uses InChIKeys in structure image URLs.
Related terms
- CAS registry number (CAS RN)A unique numeric identifier assigned by the Chemical Abstracts Service to a chemical substance, such as 7732-18-5 for water.
- InChIThe IUPAC International Chemical Identifier, an open text string that describes a chemical structure in layers.
- SMILESA line notation that writes a chemical structure as a short text string, such as CCO for ethanol.
- IUPAC nameThe systematic name of a chemical built by the nomenclature rules of the International Union of Pure and Applied Chemistry.