Parent heading

In order to find fragments of names, the field Heading Parent (HP) is the adequate field. As explained in Sect. 2.1.3, Chemical Abstracts Service indexes the names with its own rules. The Chemical Substance Index lists them according to their functional parent compound. This makes a query in the HP field a query for a parent compound. Its result will consist of a complete group of compounds, containing this parent compound, regardless of their substituents (Fig. 87). 

CN Acetophenone. 2-(4-propyl-l-piperazinyl)-. hydrochloride (6CI) (CA INDEX NAME) 

L8 ANSWER 4 OF 12209 COPYRIGHT 1993 ACS CN Acetophenone. 5 -isopropyl-2 -methoxy-4 -methyl- (6CI) 

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Polymers formed from two or more monomers such as condensation polymers and copolymers, as well as homopolymers are indexed at each inverted monomer name with the modifying term polymer with followed by the other monomer names in uninverted alphabetical order. The preferential listing for identical heading parents is in the order (1) maximum number of substituents (2) lowest locants for substituents (3) maximum number of occurrences of index heading parent and (4) earliest index position of the index heading. Examples are ... 

A systematic (e.g., CAS) name may have up to four components the heading parent, the substituents, the modifications, and the stereodescriptors. Of these, only the first is always present the others may or may not be. 

The heading parent, e.g., 2-butenoic acid, consists of a molecular skeleton (2-butene) and a suffix (-oic acid) detailing the principal functional group. There can only be one functional group in any one name. (Note elision of the terminal -e in butene.) Where there is no functional group, the heading parent consists only of a molecular skeleton name, e.g., methane, pyridine. 

The first step in choosing the index heading parent is to identify the principal functional group (the term characteristic group is now preferred by lUPAC) ... 

This contains two ketone groups which cannot be expressed as a single parent. The heading parent could either be cyclohexanone or 2-propanone but the correct name is 4-(2-oxopropyl)cyclohexanone. In order to arrive at this kind of conclusion, the following rules are applied in sequence until a decision is reached. 

In the Chemical Abstracts Service (CAS) indexing system, phenol is the heading parent and the appropriate names of alkylphenols can thus be derived by using common practices. 

The more fully systematic lUPAC rules were adapted for the highly ordered alphabetical CA indexes. Most common names and special rules for some classes of substances were discontinued in 1972. Names used in the previous CA indexes as well as trivial names used in the literature have been retained as cross-references in the CA Index Guide and in the CAS database, and are available for polymer searching and retrieval. For each identifiable substance, a rigid order of precedence of chemical functions and compound classes is followed to determine first the preferred index heading parent, and then a single preferred name. 

Systematic names of chemical substances in the indexes are arranged in inverted format as follows. The index heading parent (usually the basic skeleton name with a locant and suffix that denotes the principal function), a comma, any substituents, and any modification (derivative of the principal function). Table 11 lists some common monomers, with both common names and CA Index names. 

Functional groups are listed in decreasing order of importance in naming. Principal portions of the CAS name are found in the Heading Parent (used as the primary index entry point), secondary portions are part of the Substituent and Name Modification-, exceptions are used as shown For complete details see the latest version of the CAS Index Guide. 

In this case again the index should be consulted in order to find out whether a Heading Parent was retrieved. As every compound can only have one Heading Parent a combination of several Heading Parents through the use of proximity operators is excluded. 

The search strategy may be refined by combining it with the field Index Name Segment - Non-Heading Parent (INS.NHP). The application of the LINK operator (L) will process all the search terms in the same field CN. 

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