Rule-based nomenclature

Mention should be made of the nomenclature for the polymer. Industrially the materially is invariably known in the English-speaking world as polypropylene. However, the lUPAC name for the monomer is propene and until 1975 the recommended lUPAC name was polypropene, a term very rarely used. The latest lUPAC rules base the name of a polymer on the constitutional repeating unit, which in this case is a propylene unit (c.f. a methylene unit for polyethylene) and this leads to the name poly(propylene) (i.e. with brackets). In this volume the more common, unbracketed but still unambiguous name will be used. 

The majority of the names for chemicals in this alphabetically arranged index conform to one of the systematic series permitted under various sections of the IUPAC Definitive Rules for Nomenclature. Where there is a marked difference between these names and the alternative names recommended in the IUPAC-based BS2472 1983 or ASE 1985 nomenclature lists, or long established traditional names, these are given as synonyms in parentheses after the main title. These synonyms also have their own index entry, cross-referenced back to the IUPAC-based names used as bold titles in the text of Volume 1. 

Structure-based and source-based nomenclature rules have been extended to regular double-strand (ladder and spiro) organic polymers [7]. A double-strand polymer is defined as a polymer the molecules of which are formed by an uninterrupted sequence of rings with adjacent rings having one atom in common (spiro polymer) or two or more atoms in common (ladder polymer). 

The fundamental principles and the basic rules of the structure-based nomenclature are given first, accompanied by detailed extensions and applications. An Appendix contains names of common subunits as well as a list of acceptable source-based names, along with the corresponding structure-based names, of common polymers. There is no strong preference for the use of structure-based names over source-based names for polymers where the latter are clear and unambiguous, but for certain purposes one system of naming may be preferred to the other. 

The rules of structure-based nomenclature of regular single-strand organic polymers are of fundamental importance in polymer nomenclature. The names of other kinds of polymers such as double-strand [7] and irregular polymers [8] are based on the principles given in this Report. 

In 1985, the Commission also published rules on source-based nomenclature for copolymers [3] which by definition are polymers derived from more than one species of monomer [4]. 

The Commission acknowledges the first structure-based nomenclature rules for organic ladder and spiro polymers proposed by the Nomenclature Committee of the Division of Polymer Chemistry of the American Chemical Society [9]. 

As a general rule, chemical formulae for macromolecules should be written only in those cases where the structures of the constitutional units are known. A given structure may, however, be written in various ways to emphasize specific structural features such alternative structures need not necessarily reflect the order of citation dictated by structure-based nomenclature [2]. 

Application of this system should not discourage the use of structure-based nomenclature whenever the copolymer structure is fully known and is amenable to treatment by the rules for single-strand polymers [1, 2]. It is intended that the present nomenclature system supersede the previous recommendations published in 1952 [3]. 

Note 2 All the rules given in the two prior documents on source-based nomenclature [4,5] can be applied to the present nomenclature system, with the addition of the generic part of the name. 

The fact that several representations are possible automatically necessitates the development of rules which would allow a researcher to decide upon a preferred representation. To this end, lUPAC has developed an elaborate rules-based system using the seniority of subunits , the direction of citation, etc. [65]. However, rules-based systems are subject to the same limitations as nomenclature systems in that they, too, suffer from (potential) historical discontinuities and require acceptance by a broad community. 

Names employed in the cumulative subject index for Volumes I to VI are based upon those adopted in Volume II (Appendix, page 257) with a few changes that have been standardized and approved since publication of Volume II. No major changes seemed to be required for general conformity with the Definitive Rules for Nomenclature of Inorganic Chemistry, 1957 Report of the Commission on the Nomenclature of Inorganic Chemistry of the International Union of Pure and Applied Chemistry. 

One particular domain in which the alternate method of naming is of significance is that of natural products (perhaps, because of the occurrence of many ring assemblages). Note that this is a domain which, because of the complexity of the IUPAC nomenclature, has opted to formulate its own set of parochial rules of nomenclature, in much the same way as the organic chemistry community formulated IUPAC nomenclature to include 35 "basis" aromatic compounds on which all other "comparable" compounds were to be named [18], This is in contradistinction to various systematic approach, such as a geometry-based proposals for the fusion of benzene modules [19] and for general arenes [20],... 

Rule 1 The Main Chain The first rule of nomenclature gives the base name of the compound. 

Rule-based or systematic nomenclature (e.g., International Union of Pure and Applied Chemistry [IUPAC] or CAS nomenclature) is based on a set of linguistic rules that apply to its structure. For example, the IUPAC and CAS names for mandelic acid are 2-phenyl-2-hydroxyacetic acid and benzeneacetic acid, a-hydroxy-, respectively. The number of possible systematic names is practically endless. A small, but not nearly exhaustive, set of other systematic names includes phenylglycolic acid, phe-nylhydroxyacetic acid, ( )-a-hydroxybenzeneacetic acid, ( )-a-hydroxyphenylacetic acid, ( )-2-hydroxy-2-phenylethanoic acid, ( )-Mandelic acid, (RS)-Mandelic acid, DL-Amygdalicacid,DL-Hydroxy(phenyl)aceticacid,DL-mandelicacid,paramandelic acid, a-hydroxy- a-toluic acid, a-hydroxyphenylacetic acid, a-hydroxybenzeneacetic... 

One of the primary issues with systematic nomenclature is that some names can appear systematic in nature but, in fact, are not. They can have the expected structure of a chemical name generated according to a rules-based system but are false systematic names, at least in their specific context. When the N2S conversion algorithms... 

A significant fraction, however, of the documents in the scientific literature dealing with chemical entities and their biological effects are not composed of trivial names for the compounds under investigation. For the automated analysis of the chemical named entities in these publications, we need to use other methods. In principle, it should be possible to use rule-based approaches to identify IUPAC names (and other forms of IUPAC-like expressions), in particular, because the IUPAC name construction itself is based on rules. However, IUPAC names are neither unambiguous, nor can they easily be checked automatically for compliance with IUPAC nomenclature rules. In fact, most IUPAC-like expressions in patent literature seem to be not compliant with the IUPAC nomenclature, and cannot easily be converted into structures.40... 

IUPAC-like expressions, true IUPAC nomenclature names, and InChl and SMILES representations of chemical compounds are well suited for detection by machine learning approaches. Conditional random fields (CRFs)41 and support vector machines have been used for the detection of IUPAC expressions in scientific literature 42 Other approaches are based on rules sets43 44 or combinations of machine learning with rule-based approaches 45 All these approaches have in common that they face one significant problem the name-to-structure problem. 

Recognition of chemical nomenclature names (rule-based approach for the recognition of chemical fragment strings)... 

The parent compounds 1 and 2, however, were not synthesized until 1960 (E. Klingsberg8) and 1962 (D. Leaver et al.7), respectively. Most of the relevant papers on which this chapter is based were also published within the last 5 years. There is at present no universally applied nomenclature for the systems 1 and 2, and, in addition to that used in the present article (which follows the latest rules of nomenclature used in Chemical Abstracts), the names dithiylium 6,8 and dithiolylium 9 are also used by some groups of workers. The objections to each of the possible names have already been discussed.9... 

Figure 5 Structures and examples of nomenclature for phosphonium and carbonium salt-based reagents. Rules of nomenclature dictate that the latter be named as modified ureas see text for revised structures "ino" indicates a ring linked at the nitrogen atom.

The existing rules of nomenclature will usually permit satisfactory temporary names based upon empirical or molecular formulas. 

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