Oxoacids nomenclature

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). 

Other minor systems are also in use. Some are traditional, and some are very restricted in their application. These include acid nomenclature (inorganic, for oxoacids and derivatives), replacement nomenclature (mainly organic, to denote replacement of skeletal atoms in a parent rather than replacement of hydrogen atoms — oxa-aza replacement is one variant), functional class nomenclature (this is again principally organic and involves the use of type names such as alcohol, acid and ether) and subtractive nomenclatures (such as organic-deoxy and inorganic-debor). These will all be referred to briefly as appropriate. 

The names of heteroatomic electronegative constituents generally take the anion ending -ate, which is also characteristic of the names of anions of oxoacids (sulfate, phosphate, nitrate, etc.). Many such anions are coordination compounds, and these names are assembled using the rules of coordination nomenclature (see Section 4.4, p. 51). 

Polymeric compounds (macromolecules) do not fall easily into either of these categories, and for them a subsystem of macromolecular nomenclature has been developed. A brief introduction to macromolecular nomenclature is presented in Chapter 6. Non-stoichiometric compounds also are clearly difficult to name within the constraints of a description which generally implies localised electron-pair bonds or specific atom-atom interactions. For these, further systems of nomenclature are in the process of development. Finally, oxoacids and inorganic rings and chains have their own nomenclature variants. 

International Agreement, The first report of the Commission for the Reform of the Nomenclature of Inorganic Chemistry was written in 1926 by Delepine. Subsequent rules (1940, 1959) were expanded and improved in 1990 to provide the basis for naming inorganic compounds. They retain most of the well established names for biliary and pseudobinary compounds and for the oxoacids of the nonmetals and derivatives. 

Such oxides may therefore be considered as acid anhydrides. Table above shows a selection of oxoacids with their anhydrides and illustrates the conventional nomenclature. For example, sulphurous and sulphuric acids are display the lower (+4) and higher (+6) oxidation state, respectively, and their anions are called sulphite and sulphate. 

Termination of a name of an oxoacid of a central element in an oxidation state lower than the highest. This nomenclature is not generally., J recommended phosphorous [acid]j ... 

Oxoacid anions. Although it is quite practical to treat oxygen in the same manner as ordinary ligands and use it in the naming of anions by coordination nomenclature, some names having the suffix -ite (indicating a lower-than-maximum oxidation state) are useful and therefore are still permitted. 

The first level of nomenclature, beyond the assignment of totally trivial names, gives some systematic information about a substance but does not allow the inference of composition. Most of the common names of the oxoacids (e.g. sulfuric acid, perchloric acid) and of their salts are of this type. Such names may be termed semi-systematic and as long as they are used for common materials and understood by chemists, they are acceptable. However, it should be recognized that they may hinder compositional understanding by those with limited chemical training. 

Constructing a substitutive name generally involves the replacement of hydrogen atoms in a parent structure with other atoms or atom groups. Related operations, often considered to be part of substitutive nomenclature, are skeletal replacement (Section IR-6.2.4.1) and functional replacement in oxoacid parents (Section IR-8.6). Note that some operations in parent hydride-based nomenclature are not substitutive operations (e.g. formation of cations and anions by addition of H+ and H, respectively, cf. Sections IR-6.4.1 and IR-6.4.5). Names formed by the modifications of parent hydride names described in those sections are still considered part of substitutive nomenclature. 

Table IR-8.1 also includes anions derived from the neutral oxoacids by successive dehydronation. Many of these anions also have common names that are still acceptable, in some cases in spite of the fact that they are based on nomenclature principles that are now otherwise abandoned (e.g. nitrate/nitrite and perchlorate/chlorate/chlorite/hypochlorite). For names involving the prefix hydrogen , see Sections IR-8.4 and IR-8.5.

The chapter on Oxoacids and Derived Anions (Red Book I, Chapter 1-9) has also been extensively modified. Now called Inorganic Acids and Derivatives (Chapter IR-8), it includes the slightly revised concept of hydrogen names in Section IR-8.4 (and some traditional ous and ic names have been reinstated for consistency and because they are required for organic nomenclature purposes, i.e. in the new Blue Book). 

Note that we usually omit the prefrx mono- when there is only one H in the anion. Figure 2.12 summarizes the nomenclature for the oxoacids and oxoanions, and Table 2.6 gives the names of the oxoacids and oxoanions that contain chlorine. 

The following example deals with the nomenclature for an oxoacid and an oxan-... 

Examples of oxoacids include hypochlorous acid (HOCl), perchloric acid (HCIO4), nitric acid (HNO3), sulfuric acid (H2SO4) and phosphoric acid (H3PO4). Many well-recognized common names exist for oxoacids, and the lUPAC has recommended that such names be retained. In this book, we follow this recommendation, although in Box 6.2 we introduce systematic nomenclature. 

Systematic hydrogen nomenclature considers the oxoacid as a hydrogen salt of the corresponding conjugate base. In this way, the number of ionizable hydrogen atoms is immediately obvious. Furthermore, structural information about the... 

Inorganic chemists also use a further termination to indicate the name of a cation. This is the ending -ate, and it is used as a modification of the name of an oxoacid. Thus sulfuric acid, H2SO4, gives rise to sulfate, S04, phosphoric acid to phosphate, P04, and nitric acid to nitrate, NO3. The partially deprotonated anions such as HS04 and H2P04 are rather more comphcated to deal with, and are discussed in Nomenclature of Inorganic Chemistry, often referred to as the Red Book. 

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