Structure formula Registry File

As shown by the first prompt there are four types of search, of which we will discuss two exact and substructure (SSS). In an exact search, only information regarding exactly the stracture given will be retrieved, but even so there may well be several answers, because CA treats stereoisomers and isotopically substituted compounds as separate answers. At the conclusion of the search the system gives the number of answers, (e.g., 4). We may now look at the four answers by using the display command. As in the CA File, there is a choice of display formats, but if we choose SUB we will get (1) the Registry Number, (2) the approved CA index name, (3) other names that have appeared in CA for that compound, (4) a structural formula, and (5) the number of CA references since 1967, along with a notation as to... 

It is not necessary to build structures to use the Registry File. Compounds can also be searched for by using names, combinations of name fragments. Registry Numbers, molecular formulas, and in other ways. The display methods are the same. 

Registry File. This CAS file contains more than 11.8 million chemical substance records. About 8,000—14,000 records are added each week as new substances are identified by the CAS Registry System. The substance records contain CAS Registry Numbers, chemical names, structures, molecular formulas, ring data biosequence information, and classes for polymers. All of this information may be displayed. 

CAS ONLINE is Chemical Abstracts Service s computerized system that provides access to substance information from the CAS registry file. CAS ONLINE allows users to search for substances on the basis of structural units, registry number, chemical name, or molecular formula. Portions of the CAS information base are licensed by several information vendors. 

By means of this CAS Registry File it is possible to ascertain whether or not a substance with a certain name has already been mentioned under another name. In the course of registration for Chemical Abstracts about 6000 substances are checked daily. If not yet registered, the structural formula of the new substance is first stored. The substance is then awarded a systematic CA Index Name based on lUPAC rules, and the rules of the Chemical Abstracts Service, by a nomenclature expert (Sect. 2.1.3.2). Weekly about 13,000 structures are registered, 690,000 new substances each year (1992). 

ChemIDplus. Published by the U.S. National Library of Medicine, ChemIDplus [62] is a web-based search system, http //chem.sis.nlm.nih.gov/ chemidplus/, that provides free access to structure and nomenclature authority files used for the identification of chemical substances cited in National Library of Medicine (NLM) databases. ChemIDplus also provides structure searching and direct links to biomedical resources at NLM and on the Internet. The database contains over 349,000 chemical records, over 56,000 of which include chemical structures, and is searchable by name, synonym, CAS registry number, molecular formula, classification code, locator code, and structure. 

Answers from all of these searches contain CAS Registry Numbers. Answer sets may be combined, using the Boolean operators AND, OR, or NOT, with other answer sets or with text terms, such as names or molecular formulas. Any answer set also may be used to define subsets of the file for subsequent structure searching. Answer sets of up to 10,000 Registry Numbers from any type of search in this file may also be used as search terms in other files, such as the CA or CAOLD files (53). 

CAS CHEMICAL REGISTRY 8,000,000 compounds CHEMICAL ABSTRACTS SERVICE The world s largest file of substance information, including coordination compounds, polymers, incompletely defined substances, alloys, mixtures, and minerals. In each record, the registry number is linked to molecular structure diagram, molecular formula, CA index name, synonyms, and the ten most recent references in Chemical Abstracts. Easy crossover to the bibliographic file... 

ChemIDplus (http //chem.sis.nlm.nih.gov/chemidplus) is a search engine which allows retrieval of about 350000 chemical substance files. Files may include structure (65 000 sttuctures available), official name, systematic name, other names, classification code (therapeutic use), miolecular formula, STN locator code and CAS registry number. 

Figure 2 illustrates the basic content of a Registry substance record. The substance is tetracycline. Included are the CAS Registry Number, the CA Index Name, some synonymous chemical names, the molecular formula, and a stereospecihc structural diagram. An integral part of the CAS Chemical Registry System is the Registry Nomenclature File which contains the CA Index Name, and other systematic, semisystematic, and common names encountered in the chemical literature. 

While the Beilstein file contains a good deal of data in this area, there are also excellent compilations dedicated to thermodynamic quantities. DETHERM is produced by Dechema, and contains thermophysical properties for ca. 17000 compounds and mixtures (see Chemical Engineering Databases). The subject matter is taken from phase equilibria, PVT behavior, thermodynamic quantities, transport phenomena, surface properties, and electrolyte properties. Attention must also be drawn to the compilations of the US National Institute of Standards and Technology (NIST). The NIST Chemistry WebBook contains thermodynamic data for over 5000 compounds and ion energetics data for over 10000 compounds. The user may search on specific compounds based on name, chemical formula, or CAS Registry Number. Structures are given for all species, as well as common and commercial names. 

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