Rules IUPAC

As we cover new functional groups in later chapters, the applicable IUPAC rules of nomenclature will be given. In addition, Appendix A at the back of this book gives an overall view of organic nomenclature and shows how compounds that contain more than one functional group are named. For the present, let s see how to name branched-chain alkanes and learn some general naming rules that are applicable to all compounds. 

The common names of these simple alkyl groups are so well entrenched in the chemical literature that IUPAC rules make allowance for them. Thus, the following compound is properly named either 4-(l-methvlethyl)heptane or 4-iso-propylheptane. There is no choice but to memorize these common names fortunately, there are only a few of them. 

Alkanes are a class of saturated hydrocarbons with the general formula C H2n. -2- They contain no functional groups, are relatively inert, and can be either straight-chain (normal) or branched. Alkanes are named by a series of IUPAC rules of nomenclature. Compounds that have the same chemical formula but different structures are called isomers. More specifically, compounds such as butane and isobutane, which differ in their connections between atoms, are called constitutional isomers. 

The following two hydrocarbons have been isolated from various plants in the sunflower family. Name them according to IUPAC rules. 

As noted in the text, chemists overwhelmingly use the nomenclature system devised and maintained by the International Union of Pure and Applied Chemistry, or IUPAC. Rules for naming monofunctional compounds were given throughout the text as each new functional group was introduced, and a list of where these rules can be found is given in Table A.l. 

J According to the IUPAC rules the name alkylidene complex must be used however, carbene complex is more usual. 

In aromatic diazonium compounds containing an ionized hydroxyl group ( —O-) in the 2- or 4-position, it is necessary to consider delocalization of electrons and, therefore, two mesomeric structures (1.7a-1.7b) (see Sec. 4.2). This fact has implications for nomenclature compounds of this type are considered as quinone derivatives following IUPAC Rule C-815.3 (Exception) compounds of this class are called quinone diazides. As a specific compound 1.7a-1.7b is indexed in Chemical Abstracts as 4-diazo-2,5-cyclohexadien-l-one. If reference is made specifically to mesomeric structure 1.7b, however, it is called 4-diazoniophenolate. 

In this book we use the term diazo compounds not only to name specific structures according to the IUPAC rules but also as a generic name including neutral, cat-... 

In the Chemical Abstracts method (also accepted by IUPAC Rule C-912), the naming of monoazo compounds with radicals R derived from two identical parent hydrocarbon hydrides is the same as mentioned above (for an exception see C-912.2). If the azo group links groups that are different when unsubstituted (R-N2-R ), a parent molecule RH is treated as substituted by R -N2- (Rule C-912.4) thus, 1.8 is called 4-(2-hydroxy-l-naphthylazo)benzenesulfonic acid or 4-(2-hydroxy-... 

Nonsystematic names for organic compounds may still be found in the chemical literature and chemical supply catalogs, and so it is important to be somewhat familiar with these as well as with the IUPAC rules. Give the systematic name for (a) isobutane and (b) isopentane, (c) Formulate a rule for the usage of the prefix iso- and predict the structure of isohexane. Structures for these compounds can be found on the Web site for this book. 

Not all problems were solved, however, and different usages were encountered on the two sides of the Atlantic. A joint British-American committee was therefore set up, and in 1952 it published Rules for Carbohydrate Nomenclature [18]. This work was continued, and a revised version was endorsed in 1963 by the American Chemical Society and by the Chemical Society in Britain and published [19]. The publication of this report led the IUPAC Commission on Nomenclature of Organic Chemistry to consider the preparation of a set of IUPAC Rules for Carbohydrate Nomenclature. This was done jointly with the IUPAC-IUB Commission on Biochemical Nomenclature, and resulted in the Tentative Rules for Carbohydrate Nomenclature, Part I, 1969 , published in 1971/72 in several journals [1]. It is a revision of this 1971 document that is presented here. In the present document, recommendations are designated 2-Carb-n, to distinguish them from the Carb-n recommendations in the previous publication. 

Note When attached to an atom other than carbon, alkyl- or arylsulfonyl groups are usually known as alkane- or arenesulfonyl groups (IUPAC Rule C 631)1076 are thus considerd as acyl-type derivatives rather than sulfones. 

The nomenclature of boron compounds involves some intricacies. IUPAC rules allow the terms borabenzene or borinine for 2 the older name borin has become obsolete with the recent revision of the extended Hantzsch-Widman system (6). Anions 4 are termed boratabenzene ions an alternative would be borininate instead of the earlier borinate (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. 

It is of course possible to name individual radialenes according to IUPAC rules [e.g. per(methylene)cycloalkanes 1-4]. However, the descriptiveness of the term radialene may some day pave its way into the official nomenclature. For substituted [ ]radialenes we have proposed1 a pragmatic numbering system, in which an inner ring is numbered first, followed by an outer ring . The numbering of substituents should follow IUPAC rules. Thus, the hydrocarbon 7 is 4,4-diethyl-5,5-dimethyl[3]radialene, the ester 8 should be called 7-methoxycarbonyl-5,5-dimethyl[4]radialene, the nitrile 9 which can exist in four diastereomeric forms is (6Z,7Z)-6-cyano-5,5,7-trimethyl[4]radialene and the difunctionalized [5]radialene 10 is (7 ,6Z)-7-bromo-6-formyl-6-methyl[5]radialene. 

Although the definitions of isotactic, syndiotactic, and atactic polymers according to International Union of Pure and Applied Chemistry (IUPAC) rules are well established in terms of succession of mesa (m) or racemic (r) dyads,12 the symbolism of (+) and (—) bonds allows the easy treatments of possible configurations in cases of any complexity.1 Moreover, the (+) or (—) character of the bonds in a polymer chain is strictly related to the accessibility of gauche+ or gauche conformations of the bonds and, therefore, to the formation of right-handed or left-handed helical conformations.1... 

Fig. 2.1-4. Hypothetical parent arachno-B H 6- structures [n = 4 to 11 ar(achno)-A to flr-11] in perspective and planarized representation. Bold lines mark the apertures (Roman numbers) numbering in accord with IUPAC rules (as far as possible) or in accord with traditional m -lO(VI) numbering (in the case...

The inadequacy of the preceding nomenclature systems was apparent as the polymer structures being synthesized became increasingly complex. The IUPAC rules allow one to name... 

Before proceeding one needs to mention Chemical Abstracts (CA), a journal published by the American Chemical Society, that abstracts the world s chemical hterature and has developed its own nomenclature rules. The CA rules are generally very close to the IUPAC rules, but there are some differences. Most of the differences are not important at the level of the discussions in this book. One difference that needs to be mentioned is the placement of locants. CA does not place locants immediately before the part of the name to which they apply. Thus, the CA name for the first subunit in XV is 2,4-pyridinediyl instead of pyridine-... 

The nomenclature for this homologous series is somewhat confused. The term PANs has been used historically to denote peroxyacyl nitrates, and this terminology continues to be used extensively in the literature, despite the lack of adherence to traditional IUPAC rules of nomenclature. Because the PANs can be considered to be mixed anhydrides of carboxylic acids and nitric acid, another suggestion (Roberts, 1990) has been peroxyacetic nitric anhydride for CH,C(0)00NO2 and peroxy carboxylic nitric anhydrides for the whole class of compounds. Although it does not follow the IUPAC rules, it would be consistent with the widespread use of the name PAN but also reflect the structure more accurately. Table 6.20 shows the structures and commonly used names of some PANs that have been observed in the atmosphere and/or in laboratory studies. 

The same molecule may appear with different orientations. For example, in the current literature, the structure for the 3-ring PAH phenanthrene is drawn as (IVa), (IVb), or (IVc). While one or more IUPAC rules may be broken, their ring numberings are internally consistent. 

SELECTED IUPAC RULES FOR NAMING, ORIENTING, AND NUMBERING SELECTED PAHs... 

Note that the numbering of anthracene and 9,10-dimethylanthracene does not conform to the foregoing IUPAC rules. This common numbering is derived from anthraquinone, in which the middle, or meso, positions are numbered 9 and 10. 

Note Exceptions to IUPAC rules are designated with asterisks. 

Further soft descriptors, in particular for the description of conformations of rings, are required. Whenever available these should be selected from the IUPAC rules otherwise, clear definitions must be given ad hoc. 

The traditional descriptors cisitrans, exojendo and syn/anti are unambiguous for some important and simple types of molecules. However, their range of application is limited. The first descriptors, cis lrans, should be used according to the IUPAC rules. For bridged bicyclic molecules, the following convention8 with respect to endolexo and synjanti should be followed (see Table 9). 

There is no uniformly accepted definition of cyclophanes. Usually one understands under this name a macrocyclic or macrobicyclic compound having built-in aromatic rings. However, IUPAC rules define (cyclo)phanes much more broadly they include linear molecules containing rings that are not necessarily... 

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. 

Two further notes (1) Many transformations can be named using either of two reactants as the substrate. For example, the transformation methylene-de-oxo-bisubstitution above, can also be named ethylidene-de-triphenylphosphoranediyl-bisubstitution. In this book, unless otherwise noted, we will show only those names in which the substrate is considered to undergo the reactions indicated by the titles of the chapters. Thus the name we give to 1-12 (ArH + RCI- ArFt) is alkyl-de-hydrogenation, not aryl-de-chlorination, though the latter name is also perfectly acceptable under the IUPAC system. (2) The IUPAC rules recognize that some transformations are too complex to be easily fitted into the system, so they also include a list of names for some complex transformations, which are IUPAC approved, but nonsystematic (for some examples, see reactions 2-44, 8-36, 9-63). 

As given here, the IUPAC designations for BacI and BalI arc the same, but Rule A.2 adds further symbols so that they can be distinguished Su-AL for BalI and Su-AC for BacI. See the IUPAC rules Guthrie Pure Appl. Chem. 1989, 61, 23-56. p. 49. 

Publications on the synthesis of these compounds have almost always referred to these compounds as phthalazino-quinazolines. The title name, however, conforms better with the IUPAC rule B-3.1 on the nomenclature of organic compounds (73MI3). 

Figure 4 Morphine in the conventional presentation (left) and in a stereoformula according to IUPAC rules (right).

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. 

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