IUPAC nomenclature

Ammonia and its inorganic and organic derivatives (HNR R2) couple readily with arenediazonium ions to give triazenes (Ar — N2—NR R2). Originally these compounds were called diazoamino compounds. Nowadays IUPAC nomenclature (IUPAC, 1979, Rule 942.2) recommends that the prefix diazoamino should be used only for compounds with the same organic residue at each end of the — N2 —NH — group. 

The replacement of an electrofugic atom or group at a nucleophilic carbon atom by a diazonium ion is called an azo coupling reaction. By far the most important type of such reactions is that with aromatic coupling components, which was discovered by Griess in 1861 (see Sec. 1.1). It is a typical electrophilic aromatic substitution, called an arylazo-de-hydrogenation in the systematic IUPAC nomenclature (IUPAC 1989c, see Sec. 1.2). 

Widhalm et al. (1991) reported the use of noncrosslinked polyacrylamide for protein separation in fused silica capillaries. This matrix has low viscosity and can be replaced between separations, greatly facilitating automation of the separation. A wide range of noncrosslinked polymers has been used for size-based protein separations. Noncrosslinked polymers do not form a gel, and it is inappropriate to refer to this separation as gel electrophoresis. A number of names have been used for the method. In an effort to standardize nomenclature, IUPAC has used the term capillary sieving electrophoresis. 

Another type of anion, confined for practical purposes to boron compounds, has no unshared electrons at the anionic site, and must be thought of as being formed by addition of hydride to a boron atom (or other atom with an incomplete valence shell). Such structures were not anticipated at the time general heterocyclic nomenclature was developed, and they are only recently being fitted into systematic nomenclature (IUPAC Provisional Recommendation 83.2). Proposals for a suffix to indicate such structures are under consideration (1982). 

Organic Nomenclature IUPAC Rules 285 Cycloalkanes 286 Saturated Compounds 287 Alkenes 287... 

Nomenclature follows the recommendations of the International Union of Pure and Applied Chemistry (IUPAC) (B-79MI43800). For the description of fused heterocycles, two methods may be used, the fusion method (IUPAC Rule B-3) and the replacement nomenclature (IUPAC Rule B-4). In this chapter, the latter is used because it shows more clearly the relationship between the various structures under consideration. 

Refs. [i] Inczedy I Lengyel T, Ure AM (1998) Compendium of analytical nomenclature (IUPAC definitive rules, The Orange Book ), 3rd edn. Blackwell Science, Oxford [ii] Newman, Thomas-AlyeaKE (2004) Electrochemical Systems, 3rd edn. Wiley Interscience, Hoboken, pp 280... 

Compendium of Analytical Nomenclature, IUPAC Definitive Rules, 1997, Third Edn., J. Inczedy, T. Lengyel and A.M. Ure, Blackwell Scientific Publications, Oxford, 1998. (The Orange Book.)... 

Fig. 20-24. The principal types of optically active chelate molecules and the IUPAC nomenclature (IUPAC Bulletin No. 33, page 68, 1968).

As the science of organic chemistry slowly grew in the 19th century, so too did the number of known compounds and the need for a systematic method of naming them. The system of nomenclature we ll use in this book is that devised by the International Union of Pure and Applied Chemistry (IUPAC, usually spoken as eye-you-pac). 

A chemical name typically has four parts in the IUPAC system of nomenclature prefix, locant, parent, and suffix. The prefix specifies the location and identity of various substituent groups in the molecule, the locant gives the location of the primary functional group, the parent selects a main part of the molecule and tells how many carbon atoms are in that part, and the suffix identifies the primary functional group. 

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. 

Thomson Click Organic Interactive to use an online palette to draw alkane structures based on IUPAC nomenclature. 

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. 

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. 

Further explanations of the rules of organic nomenclature can be found online http //vvwv.acdlabs.com/iupac/nomenclature/ and in the following references... 

The IUPAC Commission on Analytical Nomenclature refers to (3) and (4) respectively as Primary Standard Solutions and Secondary Standard Solutions. 

Chlorophyll a, the green photosynthesis pigment, is the prototype of the chlorin (2,3-dihydro-porphyrin) class of products. It was first isolated by Willstatter1 at the turn of the century. The common structural unit in this class is the chlorin framework named after chlorophyll. The chromophore with a partially saturated pyrrole ring, which is formally derived from the completely unsaturated porphyrin, is less symmetric than the latter and systematically named according to IUPAC nomenclature as 2,3-dihydroporphyrin. 

The bacterioehlorin structural-type is formally derived from porphyrin by saturation of two peripheral C —C double bonds in oppposite pyrrole rings and therefore systematically named according to IUPAC nomenclature as 7,8,17,18-tetrahydroporphyrin. 

In the present IUPAC nomenclature (1979, see Sec. 2.1) diazotates are called diazoates. 

In this book we use the Nomenclature of Organic Chemistry of the International Union of Pure and Applied Chemistry, 1979 Edition ( Blue book , IUPAC, 1979), the Revised Nomenclature for Radicals, Ions, Radical Ions, and Related Species (IUPAC, 1993), and additional rules applied by the Chemical Abstracts Service for the 1987-1991 Index Guide Chemical Abstracts, 1992). 

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. 

The radical and the anion, R-N2 and R-N2, derived (formally) from a diazonium ion by addition of one and two electrons respectively, are named as diazenyl ( radical at the end is not necessary ) and diazenide (IUPAC, 1993). The radical derived formally from a diazoalkane by addition of a hydrogen atom (R=N-NH) is named diazanyl . In order to be consistent with the nomenclature of diazonium ions, the name of the parent compound should precede the words mentioned, e. g., benzenediazenyl for C6H5 - NJ (the term phenyldiazenyl radical is, however, used by Chemical Abstracts). 

We will not discuss the system for linear representation (IUPAC 1989 b), as it is not necessary to use it in this book. It is based on the same system as that for oral and written nomenclature, but has additional symbols for use in computers. 

In the present nomenclature to be called the diazonio group . In the IUPAC nomenclature for transformations this process is called diazonio-de-hydrogenation , or, in short, diazoniation . 

We have to emphasize, however, that this is only a qualitative differentiation of weights of mesomeric structures, and therefore we do not propose that the IUPAC or CA nomenclature (quinone diazides and diazo-cyclohexadien-ones, respectively) should be changed. 

The diazoazido group is an unsaturated pentazano group. As it cannot be described by only one mesomeric formula, naming it according to the IUPAC nomenclature (1979, Rule 942.1) is difficult. Therefore we use diazoazide . 

For many decades intramolecular O-coupling was considered not to take place in the diazotization products of 2-aminophenol and its derivatives (for a contrary opinion see, however, Kazitsyna and Klyueva, 1972). The compounds were assumed to be present as one structure only, which can be represented as a mesomer of a phenoxide diazonium zwitterion 6.63 b and a diazocyclohexadienone 6.63 a (see reviews by Kazitsyna et al., 1966 Meier and Zeller, 1977 Ershov et al., 1981). In IUPAC nomenclature 6.63 is called 1,2-quinone diazide, in Chemical Abstracts 6-diazo-2,4-cyclohexadien-one (see Sec. 1.3). More recently, however, Schulz and Schweig (1979, 1984) were able to identify the intramolecular product of O-coupling, i.e., 1,2,3-benzooxadiazole (6.64) after condensation of 6.63 in vacuo at 15 K in the presence of argon (see Sec. 4.2). 

In this chapter the sections are arranged in accordance with the nomenclature of substitution transformations introduced by IUPAC (1989 c). In some sections homolytic and heterolytic dediazoniations are discussed together, provided that the diazo-nio group can be replaced by a specific group or class of groups homolytically as well as heterolytically. 

In the former (Ingold) nomenclature this was called the SRN1 mechanism (see IUPAC, 1989a). This scission may consist of two steps, forming first an aryldiazenyl radical and the phenylthiolate radical (see Sec. 8.6). 

Originally the triazenes were called diazoamino compounds, but in the present IUPAC nomenclature (1979) that term may be used only for a special group of triazenes (see Sec. 1.2). 

IUPAC (1976) Rules for the Nomenclature of Organic Chemistry. Sect. E Stereochemistry. Pure Appl. Chem. 45, 11 [1.2]... 

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