Parent hydride-based nomenclature

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. 

The endings in anion names are ide (monoatomic or homopolyatomic species, heteropolyatomic species named from a parent hydride), ate (heteropolyatomic species named additively), and ite (used in a few names which are still acceptable but do not derive from current systematic nomenclature). When there is no ambiguity, the charge number may be omitted, as in Example 1 below. Parent hydride-based names do not carry charge numbers because the name itself implies the charge (Examples 3 and 4 below). 

Some variants are also allowed for mononuclear cations of Groups 15, 16 and 17. These are based on the usage of substitutive nomenclature, where the formal addition of a hydron to a parent hydride to give a cation is represented by the suffix -onium. 

Systematic substitutive nomenclature may be used to name all organic molecules. However, those that are of animal or vegetable origin have often received trivial names, such as cholesterol, oxytocin and glucose. Biochemical nomenclature is based upon such trivial names, which are either substitutively modified in accordance with the principles, rules and conventions described in Chapter 4, Section 4.5 (p. 70), or transformed and simplified into names of stereoparent hydrides, i.e. parent hydrides of a specific stereochemistry. These names are then modified by the rules of substitutive nomenclature. Three classes of compound will be discussed here to illustrate the basic approach carbohydrates amino acids and peptides and lipids. For details, see Biochemical Nomenclature and Related Documents, 2nd Edition, Portland Press, London (1992). 

Substitutive nomenclature. This system is used extensively for organic compounds, but it has also been used to name many inorganic compounds. It is often based on the concept of > parent hydride modified by substitution of hyilrogen atoms by groups I radicals). [Sec Section 1-6.J... 

Chemical nomenclature deals with names of elements and their combinations. Whereas writing the symbol or the name of an element is straightforward, a choice of which element to write first in the formula and in the name has to be made as soon as an element is associated with one or more other elements to form, for example, a binary compound. The order of citation of elements in formulae and names is based upon the methods outlined below. Furthermore, groups of atoms, such as ions, ligands in coordination compounds and substituent groups in derivatives of parent hydrides, are ordered according to specified rules. 

Substitutive nomenclature is a system in which names are based on the names of parent hydrides, which define a standard population of hydrogen atoms attached to a skeletal structure. Names of derivatives of the parent hydrides are formed by citing prefixes or suffixes appropriate to the substituent groups (or substituents) replacing the hydrogen atoms (preceded by locants when required), joined without a break to the name of the unsubstituted parent hydride. 

Secondary and tertiary amines are in most cases still named radicofunc-tionally, in a manner that can easily be transformed into a substitutive naming mode based on the parent hydride name azane. Within the boundaries of conventional substitutive nomenclature, amines of that sort are interpreted as products of N-substitution of the most serior primary amine present. 

This is the principal nomenclature system used in organic chemistry, as described in the Guide to lUPAC Nomenclature of Organic Compounds, p. 18. It is based upon the name of a formal parent molecule (normally a hydride), which is then substituted. Although it is principally an oiganic nomenclature, it has been extended to names of hydrides of Groups 14, 15, 16 and 17. 

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