Polymers Registry File

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, stmctures, molecular formulas, ring data biosequence information, and classes for polymers. AH of this information may be displayed. 

Phthalides and phthalic anhydrides are extremely common components in a huge variety of polymers, and are prepared using many chemical processes. There are over 1300 references to polymers derived from phthalic anhydrides in the Registry File of Chemical Abstracts. Phthalic anhydride itself is used in polyester resins but there are also many examples of polyimides that are derived from related anhydrides. In this section, a few examples representing a range of structure and polymerization process are presented. 

Chemical Abstracts Service (CAS) is also an authority on polymer nomenclature. CAS publishes Chemical Abstracts, which is available both in printed format and electronically via STN International, Scientific and Technical Information Network. The Chemical Abstracts Registry file provides many examples of CAS polymer nomenclature principles, which are published as Section 222 of Appendix IV in every edition of the CA Index Guide (33). 

Storage of Polymer Structures. CAS has developed comprehensive sets of nomenclature rules and structure conventions that have become standards in the world of chemical literature (see Chemical Abstracts Service Information System). CAS selects polymers for indexing according to a set of rules (5). The Registry File records are created from chemical information published in books, patents, dissertations, scientific journal articles, etc. 

Retrieval of Polymer Structures, it is axiomatic that to conduct an efficient search, searchers need to know the rules of the database or file being searched. Although this article is not intended to be a teaching manual on how to search polymer files or databases, some basic differences between searching the CAS Registry File and searching an MDL database by means of the ISIS program merit discussion. 

Searchers who choose to search a publicly available file such as the CAS Registry File must learn the rules imposed on them by CAS (2). The CAS Registry File is remotely searchable via the Scientific and Technical Information Network (STN) in Columbus, Ohio. Anyone with an STN accoimt and a computer equipped with the necessary hardware and software may access this file. As of September 2002, the Registry file contains names, structures, or both for over 42 million substances, of which nearly 934,000 are polymers. 

Structure-based versus Source-based Representation. There are no absolute rules that specify which types of polymers shall be represented as structure-based, which as source-based, and which by both methods. lUPAC makes no definitive statement about whether a polymer shall be represented as source-based or structure-based thus, polymers may be represented both ways, and many examples of this can be found in both lUPAC s publications (1,6-13) and the CAS Registry File. 

Polymers in these eight groups are usually assigned source-based names, but these groups do not necessarily correspond to specific CAS poljuner classes. A CAS publication (16) cites 42 specific poljuner classes an up-to-date list may be viewed by entering CAS Registry File online and executing the command expand A/PCT. 

STN International, Registry File Polymer Class Terms, Chemical Abstracts Service, Jan. 1993 (Publication CAS6009-1192). 

Over the last 50 years, two major organizations, CAS and lUPAC, have tackled the daunting task of how best to represent polymer structures, Their achievements are impressive, and the two organizations are in virtually complete agreement on structure-based and source-based representations of polymers, both on paper and in searchable online databases such as the CAS Registry File, However, much still remains to be done some aspects of copolymer representation need enhancement, and such newer areas as aftertreated (post-treated), comb, dendritic, and star polymers are handled inadequately. 

When the Registry Numbers of polymers are retrieved in the Registry File using the field Polymer Class Term (PCT) (Sect. 7.1.4.3), a supplementary Basic Index and abstract (search field lA) search should be conducted (Fig. 121). 

The results of both searches (polymer and monomer CAS Registry Numbers) would be combined to generate a more complete listing of the literature. The following answers (Fig. 3) are found by searching the abstracts file for CA (399 on Dialog) with the monomer and polymer Registry Numbers. 

Additional search methods include using the trade name, chemical name, and molecular formula in the Registry File to start the search for a polymer Registry Number. The table gives a starting point for common polymers, but with over 700000 polymeric entries, it is impossible to list them all. 

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... 

The price differential for manual structure input versus electronic input of existing connection tables, and the time required to build the file one compound at a time, provided much incentive to use existing CIS structure tables for input. However, problems had to be solved for input to be done electronically. New chemical input had to resemble standard Registry format. Inorganic compounds and polymers were not stored by connection table also Du Pont and CAS vised different structure conventions for certain chemical classes, for example ... 

A recent survey showed that users were enthusiastic about this new database. Cross reference to CAS Registry Numbers and the capability to search polymers by class and monomer component were perceived as advantages. Comprehensive retrieval at specific and generic levels with controlled terms as well as free text searching of the abstract text and bibliographic data afforded good flexibihty. One command language to search both Du Pont proprietary and STN files was heartily welcomed. 

When the polymer structure is well documented by the author or can be confidently assumed, because one and only one structure is chemically possible, then a supplementary representation with a corresponding systematic name is added to the CAS Registry System and included in the printed indexes and online files. 

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