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The 'IUPAC International Chemical Identifier' ('InChI'), developed by IUPAC and NIST, is a digital equivalent of the IUPAC name for any particular covalent compound. Chemical structures are expressed in terms of five layers of information — connectivity, tautomeric, isotopic, stereochemical, and electronic.
The InChI algorithm converts input structural information into the InChI identifier in a three-step process: normalization (to remove redundant information), canonicalization (to generate a unique set of atom labels), and serialization (to give a string of characters).

Contents

Examples

Layer types

Sub-layers

Notation

See also

External links

Examples

CH3CH2OH ethanol	InChI=1/C2H6O/c1-2-3/h3H,2H2,1H3
L-ascorbic acid	InChI=1/C6H8O6/c7-1-2(8)5-3(9)4(10)6(11)12-5/h2,5,7-10H,1H2/t2-,5+/m0/s1

Layer types

There are six InChI layer types:
# Main layer
# Charge layer
# Stereochemical layer
# Isotopic layer
# Fixed-H layer
# Reconnected Layer

Sub-layers

Each layer can be split into sub-layers. For example, the main layer can be split up into three sub-layers:
# Chemical formula (no prefix)
# Atom connections (prefix: "c")
# Hydrogen atoms (prefix: "h")

Notation

Layers and sub-layers are both separated by the "/" delimiter. All layers and sub-layers (except for the chemical formula sub-layer of the main layer) start with a lower-case letter indicating the type of information held in that layer.

See also

★ Molecular Query Language

★ SMILES

★ Molecule editor

External links

★ IUPAC InChI site

★ InChI.info - an unofficial InChI website featuring on-line converter from InChI to molecular drawings

★ Unofficial InChI FAQ

★ Generate InChI (interactive service at University of Cambridge, either interactive or WSDL)

★ Search Google for molecules (generates InChI from interactive chemical and searches Google for any pages with embedded InChIs). Requires Javascript enabled on browser

★ Free ChemSketch Drawing Package Chemical Structure drawing package including output to InChI file format and conversion of InChI to structure

★ PubChem online molecule editor that supports SMILES/SMARTS and InChI

★ ChemSpider Services that allows generation of InChI and conversion of InChI to structure (also SMILES and generation of other properties)

★ MarvinSketch implementation to draw structures (or open other file formats) and output to InChI file format

★ Googling for InChIs a presentation to the W3C.

★ Presentation on InChIs from the Googleplex

★ InChIMatic Draw your molecule and Google will search for it

★ BKchem implements its own InChI parser and uses the IUPAC implementation to generate InChI strings