Derwent data base

In considering the limitions of disk storage we must further consider the data base of chemical reactions which must be available to the program We have mentioned the number 25,000 as the number of synthetic reactions now existing. This is the present size of the file of Derwent.(2) Naturally, of these 25,000 the most popular 2000 are used more than all of the rest put together. Nonetheless, many molecules of interest have something special about them so that their synthesis may require an unusual reaction. Finally we observe that there is an enormous store of literature observations about reactions which show us that such and such a reaction is inappropriate when such and such a substructure is present because the desired reaction proceeds at a slower rate than that of a side reaction. These must in principle and sooner or later in fact be incorporated into any useful reaction data base. 

We are evaluating the Derwent Chemical Reactions Documentation Service as the basis of a reaction retrieval system. If Derwent succeeds in their objective of coding ca, 20,000 reactions from Theilheimer, Organic Syntheses, etc, - plus coding 4000 new reactions per year - they will create a data base which we could not hope to duplicate ourselves. 

Recently, a series of chemical substances called functional dyes have attracted considerable attention. Because such dyes have long conjugated pi-electron systems and in many cases possess intramolecular charge transfer structures, functional dyes are expected to show interesting optical and electronic properties. Among functional dyes, phthalocyanine compounds have been extensively investigated because of their excellent physical, chemical and coloristic properties, as mentioned above. For example, about 1000 related US patents, published from 1990 onwards, are retrievable from the World Patent Index data base of Derwent, and more than 30 % of these are classified in such non-colorant applications as electrophotography, catalysis, and infrared radiation absorption. 

TOPER AG (the Topological Fragment Code Generator program for chemical structure access to the Derwent patents data base) (26). 

Of the PC-based packages, PSIDOM is one that has been aimed especially at collaborative software developments. There are PsiGen interfaces to the CA Registry File (PsiCAS in STN Express) to ORAC (PsiORAC) to Derwent data... 

The Chinese patent file with its abstracts can be used to supplement WPI, which at this writing has only tides for Chinese patents. JAPIO provides abstracts based ia particular oa pateat claims, and can help to clarify uncertainties with Japanese abstracts from Derwent and/or CA. PATOLIS, ia Japanese, is a unique source of Japanese legal status information (37). EPIDOS staff carry out PATOLIS searches on request for those with sufficient need to search the PATOLIS database, software is available to enable those who cannot read Japanese to extract key data. 

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