Types of nomenclature

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. 

Chemists have developed names for materials since the beginning of the science. Initially, the names were always trivial, because the systematics of molecular structure were completely unknown. The names of the elements are still essentially trivial, but these are the basis of systematic nomenclature. 

Now that we understand much more of the way in which atoms combine, we can construct names that can give information about stoichiometry and structure. However, unsystematic usages that have their roots in the distant past are still embedded in the nomenclature. In addition, there are several systems of nomenclature, and these tend to reflect the kinds of chemistry for which they have been developed. 

This is a system based upon stoichiometry. It is not restricted to binary (two-element) compounds, but the nomenclature is binary in structure, as discussed below. 

This system is additive and was developed originally to name coordination compounds, although it can be used in other circumstances when appropriate. For a discussion, see the Nomenclature of Inorganic Chemistry, Chapter 10. The compound to be named is considered as a central atom together with its ligands, and the name is developed by assembling the individual names of the constituents. This system has also been applied to name oxoacids and the related anions. Coordination names for oxoanions are cited in the examples throughout the text, and they are presented in detail in Section 4.4.5 (p. 69). 

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An excephon to this type of nomenclature is NaC CH which is normally referred to as sodium acetylide Both sodium acetyhde and ethynylsodium are acceptable lUPAC names... 

There are several types of nomenclature systems that are recognized. Which type to use is sometimes obvious from the nature of the compound. Substitutive nomenclature, in general, is preferred because of its broad applicability, but radicofunctional, additive, and replacement nomenclature systems are convenient in certain situations. 

It is possible to regard radicofunctional nomenclature, in which the functional class narrie of a compound (c.g. alcohol, ketone, etc.) is cited after the names of the attached radicals, as involving an additive procedure (example 146). This type of nomenclature is gradually falling out of use in favor of the substitutive equivalent [for 146 the substitutive name would be l-(3-pyridyl)propan-l-one]. 

According to the triazine nomenclature, 5-azauracil is 2,4-dioxo-l,2,3,4-tetrahydro-l,3,5-triazine (2). The subject index of Chemical Abstracts prefers s-triazine-2,4(lH,3H)-dione. Furthermore, some authors use a name derived from the lactim structure, 2,4-dihydroxy-s-triazine (3). The numbering of the substituents is the same for all these types of nomenclature. 

In all types of nomenclature based on triazine the numbering of the substituents is shifted by one as compared with the nomenclature of 6-aza analogs of pyrimidines. 

Generally the name of a compound should correspond to the most stable tautomer (76AHCS1, p. 5). This is often problematic when several tautomers have similar stabilities, but is a simple and reasonable rule whose violation could lead to naming phenol as cyclohexadienone. Different types of tautomerism use different types of nomenclature. For instance, in the case of annular tautomers both are named, e.g., 4(5)-methylimidazole, while for functional tautomerism, usually the name of an individual tautomer is used because to name all would be cumbersome. In the case of crystal structures, the name should reflect the tautomer actually found therefore, 3-nitropyrazole should be named as such (97JPOC637) and not as 3(5)-nitropyrazole. 

Some compounds are simple molecules with special names. The short list containing water contains examples of this type of nomenclature. You must simply learn these names more rules do not alter the fact that H20 is water. 

Since other types of nomenclature cannot be applied to as wide a range of structures, the Sections III, A, 2-6 will deal only with principles relating to the use of substitutive nomenclature. 

The procedure for naming a compound involves some or all of the following steps, depending on the structure of the molecule under study (1) the type of nomenclature to be used (conjunctive, multiplicative, etc.) is chosen (2) the parent structure is named (3) the prefixes, suffixes, and names of funcUonal and substituent groups that were not included in (2) me attached (4) the numbering is completed. 

Owing to the wide utility of the perfluoroalkyl chains (CH2)x(CF2)yF, the shortcut Rf>,hx has been introduced to symbolize these substituents in chemical formulae (Curran, 1996). For compounds with established acronyms, it has been proposed to use the prefix z-HxFy to designate a substituent of this type in z position relative to the main functional group (Kainz et al., 1997). Both types of nomenclatures will be used in this chapter if appropriate. 

These latter two techniques are important both for spiro molecules in which the rings containing the common atom are of different constitution and for ring assembly compounds. Additionally, note that in many instances the other distinct types of nomenclature that had been introduced earlier [Cartesian (in Chapter 1) and cylindrical (in Chapter 3)] may be interconverted in much the same way as the different types of coordinate systems in geometry may be interconverted. 

A similar type of nomenclature is used for describing the isomorphous substitution of OL-1. For example, [M]-OL-1 would signify isomorphous substitution in the MnOe layers of OL-1. This preparation method is dsecribed in method 11 of Table IV. 

A clear understanding of the different types of nomenclature which are in everyday use is important. The names which are currently used to distinguish one item or substance from another can be divided into three general types systematic names, common names, and trade names. 

A few examples of other functional nomenclature are also included in Table IR-8.2 e.g. phosphoryl chloride, sulfuric diamide). These particular names are well entrenched and can still be used, but this type of nomenclature is not recommended for compounds other than those shown. Again, additive and substitutive names may always be constructed, as exemplified in the Table. 

Note that the central atom locants assigned using these rules need not coincide with those assigned when using other types of nomenclature such as substitutive nomenclature (cf. Chapter IR-6), if that is applicable, or the nomenclature systems described in Chapters II-1 or II-5 of Ref. 7. 

Common nomenclature of simple amines involves presenting the name of the alkyl group followed by the word amine (such as propylamine) this type of nomenclature is acceptable in IUPAC for simple amines. In IUPAC nomenclature, the name is based on the longest continuous chain of carbon atoms followed by the suffix -amine (such as 1-propanamine). Substituents on the carbon chain are located by a number substituents on the nitrogen are located with N (such as N-methyl-1-propanamine). The simplest aromatic amine is aniline. 

For aldol products many types of nomenclature have been proposed. Throughout this chapter the syn/anti nomenclature of Masamune is adopted and defined as shown in (3) and (4). 

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