International Chemical Identifier

The lUPAC International Chemical Identifier (InChl ) is a nonproprietary identifier for chemical substances that can be used in printed and electronic data sources thus enabling easier linking of diverse data compilations. It was... 

Elements can specify data or information in two ways. First, data can be contained between the start and end of any particular element,such as and numeric data, as in the example above, which uses both the CAS Registry Number, a unique identifier assigned to chemical structures by CAS (see Appendix 12-3), and a unique canonical molecule identifier known as InChl (International Chemical Identifier) (for more on InChl, see Appendix 8-1). 

Project Prospect endeavors to use and build acceptance of standards for chemical information by using the International Chemical Identifiers (InChls) created by the International Union of Pure and Applied Chemistry (IUPAC) as a way to provide a nonproprietary way to make chemical information more machine-readable. To illustrate the potential of this in the simplest way, an InChl for benzene (i.e., InChI=l/ C6H6/cl-2-4-6-5-3-l/hl-6H) was pasted into a Google search bar (www.google. com), this resulted in 37 hits in the fall of 2007 and over 1,000 hits 6 months later in the spring of 2008. The top hits were directed at the IUPAC Gold Book as shown in Figure 1.1. 

The most commonly used identifiers today include line notation identifiers (e.g., Simplified Molecular Input Line Entry System [SMILES] and International Chemical Identifier [InChls]), tabular identifiers (e.g., Molfile and Structure Definition [SD] file types), and portable mark-up language identifiers (e.g., Chemical Markup Language [CML] and FlexMol). Each identifier has its strengths and weaknesses as detailed in Chapter 5. Chapters 5 and 6 provide enough information to guide researchers in choosing the most appropriate formats for their individual use. 

McNaught, A. The IUPAC International Chemical Identifier InChl a new standard for molecular informatics, Chem. Int. 28(6) 12-14. 

InChl (pronounced In-chee called IChl until 2004) stands for lUPAC International Chemical Identifier, and was developed to enable the easy linking of diverse data compilations, whether print or electronic. The name InChF is protected, but use and development of InChl identifiers is free access, and the source code and associated documentation can be downloaded for free from www. iupac.org/inchi. Source codes can be modified under the terms of a public licence, and lUPAC welcomes proposals for enhancements. Following beta-testing, the current version (1.02) is full release (January 2009). 

Recently, a universal string representation method was proposed and published. The International Chemical Identifier,17 or InChl , is a definition and set of methods maintained by the International Union of Pure and Applied Chemistry. It promises to provide a truly universal character string representation of molecular structure. Whether it will replace the widely used SMILES is yet to be seen. 

REPRESENTATION OF CHEMICAL STRUCTURES WITH THE lUPAC INTERNATIONAL CHEMICAL IDENTIFIER (INCHI)... 

Representation of Chemical Structures with the lUPAC International Chemical Identifier (InChl)... 

Heller, S.R., Stein, S.E., Tchekhovskoi, D.V. InChl open access/open source and the lUPAC International Chemical Identifier, Abstracts of Papers, 230th ACS National Meeting, Washington, DC, United States, Aug. 28-Sept. 1,2005, CINF-060 ... 

The lUPAC International Chemical Identifier (InChl) is a relatively recent arrival on the chemical structure representation scene, and combines some of the characteristics of connection table, line notation and registry number identifier. A comprehensive technical description has yet to be published, though substantial details are given in the documentation which accompanies the open-source software provided by lUPAC, and a number of authors have provided good overviews. " ... 

The lUPAC International Chemical Identifier (InChl) [18] was invented in 2001. There are programs (World Wide Molecular Matrix) that can create an InChl from the molecular structure, e.g., via a MOL file [19]. For example, for benzene, the InChl is... 

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