Structure-based representations

A homopolymer that can be represented by a source-based name can usually be given a completely unambiguous structure-based representation, and such a representation should therefore be ideally accompanied by a structure-based name. A source-based name was therefore deemed redundant in these cases. 

Example the source-based name poly[(benzene-l,2,4,5-tetracarboxylic 1,2 4,5-dianhydride)-a/t-(4,4 -oxydianiline)] is ambiguous ambiguity about the structure is removed by writing poly(amide-acid) [(benzene-1,2,4,5-tetracarboxylic 1,2 4,5-dianhydride)-a/t-(4,4 -oxydianiline)] to accompany the graphical structure-based representation... 

Note For the corresponding structure-based representation, see example 8 in Section 3.9. 

Wilks, E. S. Polymer Nomenclature The Controversy Between Source-Based and Structure-Based Representations (A Personal Perspective). Prog. Polym. Sci. 25, 9-100 (2000). 

E. S. Wilks. Polymer nomenclature The controversy between source-based and structure-based representations (a personal perspective). Prog. Polym. ScL, 25(1) 9-100, February 2000. 

Example the source-based name poly(vinyloxirane) is ambiguous ambiguity about the structure is removed by writing either polyalkylenervinyloxirane to accompany the structure-based representation... 

The CA Index name of a structure-based representation is written by citation of the name of the SRU, parenthesized, and preceded by the prefix poly. Table 17 lists some examples. 

Source-based polymer representation preceded structure-based representation because polymers were made before they were structurally characterized. The... 

For some polymers the method is preferable to structure-based representation. For example, the source materials used to manufacture Bakelite or Melmac are, in practice, more important than their structures even if all the SRUs present in these highly cross-linked polymers could be delineated, to represent them thus would serve little purpose. 

Such complex structure-based representations pose no problems for more recent systems such as MDL s ISIS program with features designed expressly for polymer structiu-e storage and retrieval. 

In September 2002, CAS introduced a new on-line search-tool called POLYLINK, which is designed to solve the above problems regarding phase-shift and retrieval of structure-based representations and their source-based coimter-parts (4). 

Fig. 13. Source-based record homopolymer from hexafluorotriazatriphosphorine. Poly[nitrilo(difluorophosphoranylidyne)] [28655-96-1], the corresponding structure-based representation, is also registered in the CAS Registry file.

Wilks ES (1999) Macromolecular nomenclature note No. 17 Whither Nomenclature Polym Prep 40(2) 6-ll Wilks ES (2000a) Polymer nomenclature the controversy between source-based and structure-based representations (a personal perspective). Prog Polym Sci 25 9-100 Wilks ES (2000b) Macromolecular nomenclature note No. 18 SRUs Using the Rules. Polym Prep 41(l) 6a-l la... 

Source-based polymer representation preceded structure-based representation because polymers were made before they were structurally characterized. The introduction of structure-based representation, however, did not render source-based representation obsolete, and currently the two complementary systems coexist. Source-based representation continues to exist for several reasons ... 

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