Preferred IUPAC name

Simple binary and ternary compounds can be named by using a few simple rules, but systematic rules are required to name the millions of organic compounds that exist. Rules for naming compounds have been established by the International Union of Pure and Applied Chemistry (IUPAC). The IUPAC name stands for a compound that identifies its atoms, functional groups, and basic structure. Because of the complexity of organic compounds, thousands of rules are needed to name the millions of compounds that exist and the hundreds that are produced daily. The original intent of the IUPAC rules was to establish a unique name for each compound, but because of their use in different contexts and different practices between disciplines, more than one name may describe a compound. IUPAC rules result in preferred IUPAC names, but general IUPAC names are also accepted. 

Each of these two compounds could also be named substitutively, on the basis of the above parent hydride, or additively but the names given here are preferred IUPAC names (see Section P-67.1 of Ref. 1). 

In such cases the coordinated fragments are cited before the uncoordinated fragments in the ligand name. Alternatively, a modified name may be used, as in Example 7, where the use of the preferred IUPAC name N,A -ethane-l,2-diylbis[A-(carboxymethyl)glycine] (see Section P-44.4 of Ref. 1) is demonstrated. 

Many agents are known under non-IUPAC names. Some have been given a multitude of different names, often as a result of historic developments and national preferences. There is also a NATO (North Atlantic Treaty Organisation) code for most of the CWAs. Some of these codes are well known and are commonly used by specialists outside NATO. In the following sections the agents ate mentioned by their most commonly used names (which, in some cases, e.g. CS, is the NATO code), and where possible with the ofScial lUPAC name or formula, and the NATO code [1,6,7]. 

The coordinated ligand is called rj6-boratabenzene by Chemical Abstracts however, as ligands in sandwich-type complexes should be named as neutral entities according to the IUPAC rules, Tj6-bora-3,5-cyclo-hexadien-2-yl would be the correct name. For the sake of simplicity we prefer boratabenzene in the following. 

Quite naturally there is a certain amount of arbitrariness in this system, although the IUPAC nomenclature is followed. The preferred Chemical Abstracts index names for chemical substances have been, with very few exceptions, continued unchanged (since 1972) as set forth in the Ninth Collective Index Guide and in a journal article. Any revisions appear in the updated Index Guide new editions appear at 18-month intervals. Appendix VI is of particular interest to chemists. Reprints of the Appendix may be purchased from Chemical Abstracts Service, Marketing Division, P.O. Box 3012, Columbus, Ohio 43210. 

One starts with the IUPAC preferred name (sometimes referred to as the trivial name ) used for certain of the simple PAHs, e.g., anthracene, phenanthrene, pyrene, and fluoranthene. More complicated structures are then built up by the addition of, for example, benzo, dibenzo, or naphtho groups to the skeleton of the simple PAH. 

Define the molecular structure for which a preferred name exists in the IUPAC list (1979). 

Isatogens (1) and indolones (2) are brightly colored solids that do not occur naturally. Isatogens (I) are more comprehensively named as 3-oxo-3//-indole 1-oxides, or as the 1-oxides of indolones (2), 3-oxo-3H-indoles, or 3//-indol-3-ones. Both series of compounds are numbered in accordance with IUPAC rules. Isatogens were first reported in 18811,2 and the first indolone in 1912.3 Isatogens (1), indolones (2) and indoxyls (3) form an interrelated redox system. Indolones in which there is a methylene or methine substituent in the 2-position tautomerize to the preferred 2-methylene-3//-indol-3-one (indogenide) structures (4).4 Only passing reference will be made to 3 and 4 in this review. 

In Table 4 (drawn from Sections B and D of the IUPAC Blue Book (B-79M110200)) are listed most of the heteropolycyclic systems having trivial names still in common use. This Table also includes monocycles described in the preceding section, so as to make clear the order of preference for selection as base component in a fusion name (Section 1.02.3.3). 

The fusion name l/7-triazolo[4,5-rf]pyrimidine for (140) is preferred by practitioners in the field and appears in CA indexes. On the other hand, the nonspecialist, who may well be uncertain about his command of fusion nomenclature, might more easily grasp the replacement name l//-l,2,3,4,6-pentaazaindene. (This is an appropriate place to emphasize that, by IUPAC rules, replacement names are to be based only on a completely carbocyclic parent. Notwithstanding the attractive simplicity of 8-azapurine for the example at hand, it has no sanction see, however, Section 1.02.3.2. The purpose of this avoidance is to forestall a multiplicity of names for systems containing several hetero atoms.)... 

Although substitutive names of the type just described are preferred, the IUPAC rules also permit ketones to be named by functional class nomenclature. The groups attached to the carbonyl group are named as separate words followed by the word ketone. The groups are listed alphabetically. 

Two systems for naming spiro compounds are available. Both are described, without a statement of preference, in the IUPAC 1969 Rules however only one (method a) is used by Chemical Abstracts. 

The choice here is essentially between a fully unsaturated parent (type I, see Section II, B, 1, d) and a saturated parent (type II), and should be made with regard to simplicity, brevity, clarity, and suitability in context. (As already noted, choice of an index name by Chemical Abstracts in cases of this type is governed by an elaborate system of rules.) Application of these criteria (apart from the last, which cannot readily be exemplified) is best illustrated by a set of examples (69-74 of course the reader may not agree with the indicated preferences). It must be emphasized that partially saturated skeletons should not be used as parents. In particular the partially and fully saturated units listed by IUPAC in Rule B-2.12 should never be used in fusion names, since any saturation is automatically removed by operation of fusion principles. 

IUPAC Rules do not describe this system, but do employ it in some examples of radical names (Rules B-12), and a similar principle can be used in naming ketones, imines, bivalent radicals, and some cations (see later). It is to be preferred on the grounds that it is less cumbersome than... 

Although all alkaloids can be named by the principles already outlined in this article, the cumbersome nature of such names for complex ring systems makes it desirable to use trivial parent names for some large heterocyclic skeletons. It is preferable for such trivial names to refer to skeletons with no substituents (or very few), and it is often convenient for them to carry inherent stereochemical implications. The most extensive source of these names is the Chemical Abstracts Index Guide (or the Ninth Collective Index Nomenclature Manual), but the names given here do not correspond, in many cases, to those in common use, and IUPAC recommendations, when they appear, may well differ in some respects. Some of the principal skeletons listed by Chemical Abstracts are illustrated (122-130). 

Current IUPAC and Chemical Abstracts nomenclature has been employed in this index with the former given preference. Substitutive nomenclature has been given preference over radicofunc-tional, additive, subtractive, conjunctive or replacement nomenclature, except where this becomes unwieldy. With many bicyclic and polycyclic compounds bearing heteroatoms, standard bicyclic or polycyclic oxa, aza, and thia replacement nomenclature has often been used. With certain functional groups, where the names are rather complex and probably not familiar to most organic chemists, such as ylides, those compounds have simply been named as sulfur, tellurium and arsonic ylides. Metal catbenes have been treated similarly. With more complex functionality and many heterocycles, the Beilstein Commander Crossfire nomenclature system has been used with certain modifications. 

According to the latest IUPAC Convention the names of ligands surrounding the central metal atom are written in alphabetical order of preference irrespective of whether they are negative or neutral. For example, in the complex [Co(NH3)4 C1(N02)], the ligands are named in the order ammine, chloro and... 

This is seen in its examples of 3-Penten-l-yne vs. l-Penten-4-yne, where the combined numbers 1,3 are selected as the priority numbering in the first of these names however, since the same numbering 1,4 would result in the second of these compounds, the "-ene" is given preference. Moreover, in writing the IUPAC canonical name, the suffix "-ene" always precedes the "-yne". 

Alcohols with two —OH groups are called diols or glycols. They are named like other alcohols except that the suffix diol is used and two numbers are needed to tell where the two hydroxyl groups are located. This is the preferred, systematic (IUPAC) method for naming diols. 

Nomenclature The most recent IUPAC nomenclature is stressed throughout the book, but common nomenclature is also discussed and used to develop students familiarity. Teaching only the IUPAC nomenclature might be justifiable in theory, but such an approach would handicap students in their further study and use of the literature. Much of the literature of chemistry, biology, and medicine uses common names such as methyl ethyl ketone, isovaleric acid, methyl tert-butyl ether, -y-aminobutyric acid, and e-caprolactam. This book emphasizes why systematic nomenclature is often preferred, yet it encourages familiarity with common names as well. 

Reduction of one or two double bonds in the azole ring gives nonaromatic systems. Historically, these derivatives have been described as azolines and azolidines, as illustrated by the pyrazole derivatives 25 and 26. In 3-pyrazoline 25 the 3 indicates the first ring atom associated with the double bond . In the older literature the position of the double bond is indicated by An, where n is the number of the first ring atom associated with the double bond, e.g., A3-pyrazoline 25. Alternatively, they are named as dihydro or tetrahydro derivatives of the parent azole (e.g., 2,5-dihydropyrazole 25) and this nomenclature is IUPAC-preferred nomenclature for rings with more than two heteroatoms . 

Polymer names are often one or two words in parentheses following the prefix poly . Poly is a syllabic prefix, not a descriptor, and thus is set in roman type. Here is a short list of correctly formatted names of frequently cited polymers. (These names are not necessarily IUPAC or CA index preferences.)... 

This quantity is equal to the value of Q in equilibrium, when the affinity is zero. It is dimensionless and its value depends on the choice of standard state, which must be specified. ISO [5.i] and the IUPAC Thermodynamics Commission [24] recommend the symbol K and the name standard equilibrium constant , but some thermodynamicists prefer the symbol K and the name thermodynamic equilibrium constant . 

So far, we have identified coordination compounds only by their chemical formulas, but names are also useful for many purposes. Some substances were named before their structures were known. Thus, K3[Fe(CN)g] was called potassium fer-ricyanide, and K4[Fe(CN)g] was potassium ferrocyanide [these are complexes of Fe (ferric) and Fe (ferrous) ions, respectively]. These older names are still used conversationally but systematic names are preferred to avoid ambiguity. The definitive source for the naming of inorganic compounds is Nomenclature of Inorganic Chemistry-IUPAC Recommendations 2005 (N. G. Connelly and T. Damhus, Sr., Eds. Royal Society of Chemistry, 2005). 

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