What is the InChI Code?

1. What on Earth is InChI?
Introduction of the InChI standard – the International Chemical Identifier – to represent chemical structures.

2. The Birth of the InChI
Background to the development of the InChI standard.

3. The Googlable InChIKey
Describes how an InChIKey enables chemical structures to be uniquely identified on the web, using as a basis the InChI standard.

4. InChI and the Islands
Describes how the InChI standard enables the linking of information on a chemical structure from a variety of sources like databases and journals.

  • Author: IUPAC
  • Published: 09 April 2013
  • Source/Publisher: International Union of Pure and Applid Chemistry (IUPAC)
  • Associated Societies: International Union of Pure and Applied Chemistry (IUPAC)

The IUPAC International Chemical Identifier (InChI) is an identifier for chemical substances enabling easier linking of diverse data compilations.
It starts with the string "InChI=", the version number – currently 1 – and the letter S for standard InChIs. This is followed by layers of information separated by the delimiter "/". The first layer gives the chemical formula, the second the connectivity of the main atoms, and the third the positions of the hydrogen atoms. Others give information on stereochemistry, charges, etc.

The InChIKey, sometimes called hashed InChI, is a 25 character condensed digital representation of the InChI. It is not human-understandable and was introduced to facilitate web searches for chemical compounds.

The videos – which were launched at the ACS Meeting in New Orleans – give an easy and short explanation.

More from the ACS Meeting:

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