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Name-based representations

Fig. 9.6 Human versus machine-readable chemical structure representations. Names based on the depicted structures were interpreted using ACDName [22]. The cross up/down wedge error (middle) causes errors in assigning the absolute chirality. Fig. 9.6 Human versus machine-readable chemical structure representations. Names based on the depicted structures were interpreted using ACDName [22]. The cross up/down wedge error (middle) causes errors in assigning the absolute chirality.
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. [Pg.263]

Example the source-based name poly(vinyloxirane) is ambiguous ambiguity about the structure is removed by writing either polyaUcyleneivinyloxirane to accompany the source-based representation,... [Pg.263]

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... [Pg.266]

CA s policy for naming acetylenic, acrylic, methacrylic, ethylenic, and vinyl polymers is to use the source-based method, and source-based representation is used to depict the polymers graphically thus, a synonym for polyethylene is polyethylene and not poly(1,2-ethanediyl) a synonym for polypropylene is polypropylene, and poly(vinyl alcohol) is named ethenol homopolymer although ethenol does not exist. Thus, these polymers are named and represented structurally by the source-based method, not the structure-based method. [Pg.734]

Because there is no unique principal axis in D2, the Mulliken conventions are not used in naming the representations of D2. These two groups are isomorphous and the character systems of the four IRs are identical, but corresponding representations are labeled differently, which tends to obscure rather than emphasize the isomorphism. Note that C2x and ox are corresponding elements, and so are C2y and totally symmetric representation in D2). In C2V, the Mulliken designations B and B2 are arbitrary because there are two equivalent improper binary axes normal to z. [Pg.138]

Polymeric substances are represented on the TSCA Inventory in one of two ways. Depending on the type of polymer, a monomer-based representation or a structnral repeating nnit (SRU) representation is nsed. In either case, EPA generally reqnires that the naming of chemical snbstances be done with as mnch specificity as possible, based on knowledge of the chemical strnctnre. [Pg.74]

The names in parentheses are those commonly used for molecular-fingerprint-based similarity functions. All of the similarity functions are symmetric. Similarity functions for function-based representations are identical in form to those for vector-based representations except that the summations are replaced by integrations over the corresponding function spaces [41]. [Pg.364]

There is no provision for structuring and naming end groups in source-based representations, except for ester-terminated polymers (see Table 14) and mixed polyalkylene glycols (see below). [Pg.5062]

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. [Pg.5064]

For source-based representations, lUPAC recommends that alternating and periodic copolymer names contain the connectives -alt- and -per-, respectively. [Pg.7842]

CAS makes no distinction among ordered, segmented, and imordered block pol5uners. For source-based representation, block polymers are distinguished from random pol5uners by indexing as copolymers at the monomer names. The term block is cited in a special modification after all other structin-al information (2). [Pg.7843]

For source-based representations, lUPAC recommends that alternating and periodic copolymer names contain the connectives -alt- and -per-, respectively. Table 1 lists the source-based connectives recommended by lUPAC for alternating, periodic, and several other polymer types. According to the above lUPAC rules, the source-based name for PET and the trivial name nylon-66 represent alternating copolymers,... [Pg.2144]

Two-Dimensional Representation of Chemical Structures. The lUPAC standardization of organic nomenclature allows automatic translation of a chemical s name into its chemical stmcture, or, conversely, the naming of a compound based on its stmcture. The chemical formula for a compound can be translated into its stmcture once a set of semantic rules for representation are estabUshed (26). The semantic rules and their appHcation have been described (27,28). The inverse problem, generating correct names from chemical stmctures, has been addressed (28) and explored for the specific case of naming condensed benzenoid hydrocarbons (29,30). [Pg.63]

With the view that a KBS interpreter is a method for mapping from input data in the form of intermediate symbolic state descriptions to labels of interest, four families of approaches are described here, each offering inference mechanisms and related knowledge representations that can be used to solve interpretation problems namely, model-based approaches, digraphs, fault trees, and tables. These methods have been heavily used... [Pg.67]


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