Vol. 23, No.3
IUPAC Chemical Identifier (IChI)
IUPAC has approved a project to establish a unique label, the IUPAC
Chemical Identifier (IChI), as a non-proprietary identifier for chemical
substances that could be used in printed and electronic data sources,
thus enabling easier linking of diverse data and information compilations.
IChI will not require the establishment of a registry system. Unlike
the CAS Registry System, it will not depend on the existence of a database
of unique substance records to establish the next number for any new
chemical substance being assigned an IChI. It will use a yet-to-be-defined
set of IUPAC structure conventions, and rules for normalization and
canonicalization of the structure representation to establish the unique
label. It will thereby enable an automatic conversion of a graphical
representation of a chemical substance into the unique IChI label, which
can be performed anywhere in the world and which could be built into
desktop chemical structure drawing packages (such as ChemDraw, ISIS/Draw,
etc.) and online chemical structure drawing applets (such as ACD/Draw).
IUPAC would define the process flow leading from input of structural
information to the creation of the Identifier in three steps: definition
of chemical structure input requirements, algorithms for generating
a unique set of atom labels (canonicalization), and algorithms for conversion
of these labels into the Identifier (serialization). Structure input
and conversion to the structural format required by the IChI generator
would be carried out with vendor-developed software.
The process would be reversible, so that the Identifier output could
be used to regenerate structural input information. The Identifier would
thus serve as the computer equivalent of the IUPAC name for a molecule.
This arrangement would facilitate searching the Internet and labeling
information in electronic documents with the name of the chemical substance
in question. A prototype algorithm with limited applicability is expected
to be available for testing toward the end of 2001.
Comments from the chemistry community are welcome and should be addressed
to the project coordinator, Dr. Alan McNaught, General Manager, Production
Division, RSC Publishing, Royal Society of Chemistry, Thomas Graham
House, Science Park, Milton Road, Cambridge CB4 0WF, England, UK, Tel.:
+44 1223 432119, Fax: +44 1223 420247; E-mail: [email protected] See http://www.iupac.org/projects/2000/2000-025-1-050.html
for project description and update.