Examples of Systematic Nomenclature

Finally, the systematic nomenclature of heterocyclic compounds wiU be illustrated by a few complex examples  

An analysis of the system reveals two benzene rings, one pyrazole ring and one 1,3-diazocine ring, the latter ring being the base component according to the fourth criterion. The square brackets [1,3] indicate that the position of the two heteroatoms is not the basis for numbering the whole system. 

According to the third criterion, quinoxaline is the base component The heterocycle imidazole, which is fused to the base component, is numbered in the usual way the pyridine ring, however, is denoted by 1, 2, and so on, and it is not necessary to mark the double bonds. Pyrido[T,2 l,2]imidazo denotes one ring fusion, imidazo[4,5-b]quinoxaline the 

With ring atoms such as phosphorus, which can be tri- or pentavalent, a non-standard bonding number is indicated as an exponent of the Greek letter A, after the locant In the example, this is shown by (the 1993 Blue Book, p. 21). 

The name is constructed according to replacement nomenclature. The basic hydrocarbon with the greatest number of noncumulative double bonds is cyclopenta[c,d]indene. Note the retention of the numbering. 

In this case, [b,e] is omitted after dibenzo since there is no other possibility for ring fusion. This compound is also known as TCDD or Seveso dioxin. 

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In more recent publications a new, more systematic nomenclature for hydrides and complex hydrides has been adopted. Examples of both nomenclatures are shown below ... 

Emphasis has been placed on the use of systematic nomenclature consistent with recommendations of the International Union of Pure and Applied Chemistry and/or the Chemical Abstracts Service. However, in some instances, a factor such as a strong preference of the author or common usage has influenced the choice. In several such instances, an alternative name as a synonym has been included at least once within the article. For example, in synthesis 20, three names are ven for the eight-membered ring compound N4P4(OC2Ht)g octaethoxycyclotetraphos-phazatetraene tetrameric ethyl phosphonitrilate and... 

Systematic names formed by applying the principles of substitutive nomenclature are single words except for compounds named as acids. First one selects the parent compound, and thus the suffix, from the characteristic group listed earliest in Table 1.7. All remaining functional groups are handled as prefixes that precede, in alphabetical order, the parent name. Two examples may be helpful ... 

The nomenclature (qv) of polyamides is fraught with a variety of systematic, semisystematic, and common naming systems used variously by different sources. In North America the common practice is to call type AB or type AABB polyamides nylon-x or nylon-respectively, where x refers to the number of carbon atoms between the amide nitrogens. For type AABB polyamides, the number of carbon atoms in the diamine is indicated first, followed by the number of carbon atoms in the diacid. For example, the polyamide formed from 6-aminohexanoic acid [60-32-2] is named nylon-6 [25038-54-4], that formed from 1,6-hexanediamine [124-09-4] or hexamethylenediamine and dodecanedioic acid [693-23-2] is called nylon-6,12 [24936-74-1]. In Europe, the common practice is to use the designation "polyamide," often abbreviated PA, instead of "nylon" in the name. Thus, the two examples above become PA-6 and PA-6,12, respectively. PA is the International Union of Pure and AppHed Chemistry (lUPAC) accepted abbreviation for polyamides. 

Synthesis by oxidation remains the first choice for commercial and laboratory preparation of quinones the starting material (1) provided the generic name quinone. This simple, descriptive nomenclature has been abandoned by Chemicaly hstracts, but remains widely used (2). The systematic name for (2) is 2,5-cyclohexadiene-l,4-dione. Several examples of quinone synonyms are given in Table 1. Common names are used in this article. 1,2-Benzoquinone (3,5-cydohexadiene-l,2-dione) (3) is also prepared by oxidation, often with freshly prepared silver oxide (3). Compounds related to (3) must be prepared using mild conditions because of their great sensitivity to both electrophiles and nucleophiles (4,5). 

Many names in common use for heteropolycycles provide little or no information about structure. Most such names were introduced long before any serious attempts were made to systematize nomenclature, and although more systematic equivalents can now be coined in many cases (for example, indole can be named benz[f)]azole or 1-azacyclopentabenzene), it is likely that the use of a substantial residue of trivial names will continue. However, one would not expect many new trivial names to be introduced in the future, except in the natural product area (see Section 1.02.4). 

In Table 1, drawn up by the author, of abbreviations in common use those in bold type are in the main schedule of BS 3502. In this list the names given for the materials aie the commonly used scientific names. This situation is further complicated by the adoption of a nomenclature by the International Union of Pure and Applied Chemistry for systematic names and a yet further nomenclature by the Association for Science Education which is widely used in British schools but not in industry. Some examples of these are given in Table 2. Because many rubbery materials have been referred to in this book. Tables 3 and 4 list abbreviations for these materials. 

Figure 8.1 Example of (a) a structure diagram, (b) systematic nomenclature, (c) connection table in MDL format (see URL http //www.mdli.com), and (d) SMILES for a molecule.

There is no systematic nomenclature developed for molecular sieve materials. The discoverer of a synthehc species based on a characteristic X-ray powder diffraction pattern and chemical composihon typicaUy assigns trivial symbols. The early syn-thehc materials discovered by Milton, Breck and coworkers at Uruon Carbide used the modem Lahn alphabet, for example, zeoHtes A, B, X, Y, L. The use of the Greek alphabet was inihated by Mobil and Union Carbide with the zeoHtes alpha, beta, omega. Many of the synthetic zeoHtes which have the structural topology of mineral zeoHte species were assigned the name of the mineral, for example, syn-thehc mordenite, chabazite, erionite and offretite.The molecular sieve Hterature is replete with acronyms ZSM-5, -11, ZK-4 (Mobil), EU-1, FU-1, NU-1 (ICI), LZ-210, AlPO, SAPO, MeAPO, etc. (Union Carbide, UOP) and ECR-1 (Exxon). The one pubHcaHon on nomenclature by lUPAC in 1979 is Hmited to the then-known zeoHte-type materials [3]. 

The alcohol portion in hyoscyamine is tropine in hyoscine it is the epoxide scopine. Tropine is an example of an azabicyclo[3,2,l]octane system with a nitrogen bridge, whereas scopine is a tricylic system with a three-membered epoxide ring fused onto tropine. Note that systematic nomenclature considers an all-carbon ring system with one carbon replaced by nitrogen hence, tropane is an azabicyclooctane (see Section 1.4). 

The formation of a systematic name for a polymer requires the identification and naming of a preferred constitutional repeating unit (CRU). This basic name is then modified by prefixes, which convey precisely the structural identity of the polymer in question. Such names are referred to as structure-based names. However, polymers can also be named as being derived from a monomer (or precursors), named according to lUPAC rules. Such names are referred to as source-based names. Over the years, rules for determining polymer nomenclature under these two systems have developed in parallel. An example of the modification of the lUPAC name of an organic molecule to lUPAC structure-based and source-based names of a polymer is illustrated below. 

Specialists in nomenclature recognise two different categories of nomenclature. Names that are arbitrary (including the names of the elements, such as sodium and hydrogen) as well as laboratory shorthand names (such as diphos and LithAl) are termed trivial names. This is not a pejorative or dismissive term. Trivial nomenclature contrasts with systematic nomenclature, which is an assembly of rules, themselves arbitrary. The function of specialists in nomenclature is to codify such rules so that everyone can use them to identify pure substances, rather like many of us use an alphabet to represent words. There may be more than one way to name a compound or species, and no one way may be superior to all the others. Names also vary in complexity, depending upon how much information needs to be conveyed. For example, a compositional name conveys less information than a structural (or constitutional) name, because this includes information about the arrangement of atoms in space. 

In other areas, such as oxo acids, a great deal of traditional, inadequate semi-systematic nomenclature (for example, the names of phosphorus acids) will have to be abandoned before a more rigorous nomenclature can be adopted and generally understood. There is much work yet to do. 

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