Molecular Formula Search

Bibliographic data Substance identification data Molecular formula search Reaction data... 

Molecular formula search and molecular mass search. 

In the toolkit concept, a tool fulfils a specific function, can be used independently, may easily be replaced by another tool as necessary and is fully documented with respect to its function, implementation and use. A simple example of a tool is a molecular formula search module, which may be implemented for use within a DBMS, is easily replaceable by another molecular formula search module and whose molecular formula search capabilities and calls from any apphcation are fully documented. DARC tools are classified as simple tools and advanced tools. Examples of simple tools are ... 

Factual databases may provide the electronic version of printed catalogs on chemical compoimds. The catalogs of different suppliers of chemicals serve to identify chemical compounds with their appropriate synonyms, molecular formulas, molecular weight, structure diagrams, and - of course - the price. Sometimes the data are linked to other databases that contain additional information. Structure and substructure search possibihties have now been included in most of the databases of chemical suppliers. 

Thus, if the user wants to look for literature including requested chemicals or reactions, it is possible to query the database by the first option Chemical Substance or Reaction , The compound can be entered as a query in three different ways drawing the chemical structure in a molecule editor (Chemical Structure) searching by names or identification number, such as the CAS Number (Structure Identifier) and searching by molecular formula (Figure 5-12). 

As already mentioned (Section 5.3), the stored structure information in this type of database makes it possible to search for chemical structures in several ways. One method is to draw a structure (via a molecule editor) and to perform either a precise structure search (full structure search) or a search containing part of the input structure (substructure search) (see Sections 6.2-6.4). The databases also allow the searching of chemical names and molecular formulas (see Section 6.1). The search results are in most cases displayed in a graphical manner. 

Answers from aH 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 stmcture 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). 

CRS provides information on chemical substances and how they are represented in the Environmental Protection Agency regulations and data systems. A search engine for chemicals by CAS number, name, molecular formula, chemical type, definition, or other data identifiers. 

It is not necessary to build stmctures 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. 

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. 

Users can easily search the CD-ROM by employing the Aldrich catalog number, Chemical Abstracts Service (CAS) number, chemical name, or molecular formula. One can also export the chemical structures to some supported software for subsequent inclusion into word processing programs. The product is available from Aldrich Chemical Company, Inc., 940 West St. Paul Ave., Milwaukee, WI 54233. 

Searches through the MSSS data base can be carried out in a number of ways. With the mass spectrum of an unknown in hand, the search can be conducted interactively, as is shown in Figure 5. In this search the user finds that 24 data base spectra have a base peak (minimum intensity 100% maximum intensity 100%) and an m/e value of 344. When this subset is examined for spectra containing a peak at m/e 326 with intensity of less than 10%, only 2 spectra are found. If necessary, the search can be continued in this way until a manageable number of spectra are retrieved as fulfilling all the criteria that the user cited. These answers can then be listed as is shown. Alternatively, the data base can be examined for all occurrences of a specific molecular weight or a partial or complete molecular formula. Combinations of these properties can also be used in searches. Thus all compounds containing for example, five chlorines and whose mass spectra have a base peak at a particular m/e value can be identified. 

The aids to chromatography include a) resolution calculations on chromatograms of standard mixtures to monitor column performance, b) calculation of Kovats retention index for help in identifying peaks, and (c) multiple point calibration curves for improved quantitation. The file searching routines access two sets of data. Information (such as molecular formula, molecular weight) is stored on 3100 compounds from the Arctander data( ). This allows a quick computer search through the data which is difficult... 

Because the electrochemistry of pyridines has not been reviewed before with regard to industrially significant processes, this review will therefore cover the period 1801-1983. Citations from 1801-1975 have been compiled in Swann s bibliography.1 These citation listings were broken down into six indices author, patent, product molecular formula, synonym, product name, and product type. A computer-aided search of Chemical Abstracts and the World Patent Index covered the period 1967-1983. Other sources such as the reviews on heterocyclic electrochemistry by Lund2 and Nelson3 contained useful citations. Nelson s review has a valuable table that summarizes the synthetic work by indexing the parent heterocycle. 

SciFinder Scholar lets students and faculty search the CAPlus and Registry databases by authors names, concepts, chemical names, molecular formulas, CAS Registry Numbers, chemical structures, and specific references such as a patent number. SciFinder allows these options, plus other ones for handling the queries and hits. The latest version of SciFinder also can search Medline. 

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