Index of Ring Systems

The Formula Index and the Index of Ring Systems are both tools which enable the Chemical Substance Index to be used more effectively. 

The description of a ring system consists of three components (this is called the ring analysis)  

Ring size (number of atoms comprising a ring) 

Elemental analysis of the component rings (excluding hydrogen). 

Number of component rings 4-Ring System Numbers of atoms per ring 5,5,6,6 

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Along with each index (annual, semiannual, or collective) appears an index of ring systems. This valuable index enables the user to ascertain immediately if any ring system appears in the corresponding subject or chemical substance index and under what names. Eor example, someone wishing to determine whether any compounds containing this ring system... 

The Index of Ring Systems was discontinued after the twelfth Collective Index period. For the 1st to the 6th Collective Indexes, Ring System Information was included in the introduction to the Subject Index for the 7th to the 12th Collective Indexes, the Index of Ring Systems was bound with the Formula Index. 

Appendix II Indexes to Chemical Abstracts Organisation and Use is a comprehensive account of the organisation, and relationships, of the CA Chemical Substance Index, CA General Subject Index, CA Formula Index, and CA Index of Ring Systems. This appendix also describes the CAS Chemical Registry System and the criteria applied in selecting CA index entries. 

Fig. A.4. Alphabetized index of ring systems referred to in Tabie A.3 the numbering scheme used in assembling the bond length data is given where necessary...

This chapter summarizes the syntheses of various tetracyclic and pentacyclic condensed thiophene systems that are reported in Chemical Abstracts, Index of Ring Systems for the period from 1952 through December 31, 1980 (i.e., through Volume 93). Previous syntheses are reported in the monograph... 

The print edition of Chemical Abstracts appeared in weekly issues. Six months of these issues constituted a volume that was accompanied hy six indexes General Subject Index, Chemical Substance Index, Formula Index, Index of Ring Systems, Author Index, and Patent Index [12], January to June of 1993 was volume 118. Ten volumes (5 years coverage) were combined in the Collective Indexes, the 11th collective volumes covered the years from 1982 to 1986 and comprised 93 hound hooks occupying 17 feet of shelf space. It is easy to see why the print version is no longer published. 

Salinomycin is entered in the Index of Ring Systems under both ring analyses (Fig. 26). 

Thus, this CA volume contains abstracts about this substance or one or more of its derivatives. As no abstract numbers are given, the systematic CA Index Name obtained from the Index of Ring Systems is used to continue the search in the Chemical Substance Index which contains fiirther information about the substance itself and possibly also about its derivatives. 

Index of Ring Systems (contained in the introduction to the Subject Index) X X X X X X X... 

Fig. 69. Excerpt from the Index of Ring Systems to the 9th collective period...

In the Index of Ring Systems for the ninth collective period there are various substance names mentioned under this ring analysis (Fig. 69). Every chemist should recognize that this ring system is a spiro substance with a cyclohexane ring. Thus, the choice of alternative names to be consulted in the Chemical Substance Index is reduced to three. 

The Chemical Substance Index shows the structure diagram immediately after the CAS Registry Number. Now it can be ascertained if this is the correct ring system (Fig. 70). The structure diagram of all cyclic parent compounds, i.e. all compounds mentioned in the Index of Ring Systems, are illustrated in the Chemical Substance Index. These ring skeletons are also shown in the Ring Systems Handbook (Sect. 5.1). 

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