Nomenclature systems IUPAC system

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 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. 

Some of the rigidly systematic names selected by the Association for Science Education for their nomenclature list in 1985 from the IUPAC possibilities, and some of the systematic indexing names used by Chemical Abstracts since 1972, are given as synonyms in the Index of Chemical Names (Appendix 4). This should assist those coming into industry and research with a command of those nomenclature systems but who may be unfamiliar with the current variety of names used for chemicals. The inclusion where possible of the CAS Registry Number for each title compound should now simplify the clarification of any chemical name or synonym problems, by reference to the Registry Handbook or other CAS source. 

The naming of these three heterocyclic fused (5 5 5) ring systems has been carried out according to the IUPAC system of nomenclature. Some examples are given as follows compound la (Table 1) is named (3-hydroxy-4-methoxyphenylthieno[2,3-3]pyrrolizin-8-one. Compound 15a (Table 2) is dithieno[3,2-3 2, 3 - 1thiophene. Compound 23a (Table 2) is dithieno[3,2-3 2, 3 - 1pyrrole. Compound 20a (Table 2) is dithicno[3,2-3 2, 3 -r/]thiophene-4,4-dio ide. Compound 13b (Table 2) is 3,4-dimethyldithieno[3,2-3 2, 3 -i/]thiophene-7,7-dioxide. Compound 38 (Table 4) is fM, r, r-10-azatricyclo[5.2.1.01 10]deca-2,5,8-triene. Compound 39 (Table 4) is cis,cis, m-10-azatricyclo[5.2.1.01 10]deca-2,8-diene. The nomenclature of compound 40 (Table 4) is 1,4,7 triaza tricy-clo[5.2.1.01,10]decane. 

In the/flc isomer, the three chloride ions are located on the corners of one of the triangular faces of the octahedron. In the mer isomer, the three chloride ions are located around an edge (meridian) of the octahedron. The IUPAC system of nomenclature does not use this approach. A summary of the IUPAC procedures is presented in the book by Huheey, Keiter, and Keiter that is cited in the references listed at the end of this chapter. 

Fig. 2. Nomenclature of the heme group of horseradish peroxidase according to the lUB/IUPAC system. Proton-bearing carbon atoms are numbered on the structure and can be cross-referenced with the Fischer system as follows ...

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... 

In the IUPAC system locants are placed immediately before the part of the name to which they apply for instance subunits such as pyridine-2,4-diyl and l-methylpropane-l,3-diyl. One of the few exceptions is the phenylene subunit, for example, 1,4-phenylene in XV. The IUPAC nomenclature system is always evolving and some of the details (e.g., the names of some subunits) have changed in recent years. One should use caution when using less recent nomenclature references than those listed in this text. 

The IUPAC nomenclature system recognizes that most of the common (commercial) polymers have source-based or semisystematic names that are well established by usage. IPUAC does not intend that such names be supplanted by the IUPAC names but anticipates that such names will be kept to a minimum. The IUPAC system is generally used for all except the common polymers. The IUPAC names for various of the common polymers are indicated below the more established source or semisystematic name in the following ... 

Lactams are named in several ways. They are named as alkanolactams by the IUPAC substitutive system, such as 3-propanolactam, 4-butanolactam, 5-pentanolactam, and 6-hexano-lactam, respectively, for the 4-, 5-, 6-, and 7-membered rings, respectively. An alternate IUPAC method, the specialist heterocyclic nomenclature system, names these lactams as 2-azetidinone, 2-pyrrolidinone, 2-piperidinone, and hexahydro-2f/-azepi n-2-one, respectively. These lactams are also known by the trivial names fl-propiolactam, a-pyrrolidone (y-butyrolactam), a-piperidone (8-valerolactam), and e-caprolactam, respectively. 

The nomenclature of boron hydride derivatives has been somewhat confusing and many inconsistencies exist in the literature. The structures of some reported boron hydride clusters are so complicated that only a structural drawing or graph, often accompanied by explanatory text, is used to describe them. Traditional nomenclature systems often can be used to describe compounds unambiguously, but the resulting descriptions may be so long and unwieldy that they are of litde use. The IUPAC (7) and the Chemical Abstract Service (8) have made recommendations, and nomenclature methods have now been developed that can adequately handle nearly all clusters compounds however, these methods have yet to be widely adopted. For the most part, nomenclature used in the original literature is retained herein. 

It is unfortunate that two systems of nomenclature are currently being used in this area. Though this author, like most in the United States, has a personal preference for the Fischer system (11) (because it retains a link with the monumental body of earlier work), the IUPAC system (12) is mandated in this chapter. To be sure, the IUPAC system has its advantages, not the least of which is the correlation of atoms between the porphyrin (12) and corrin (13) chromophore. 

In the IUPAC system, the four methine positions are conveniently numbered 5, 10, 15 and 20, and the eight remaining peripheral positions fall at 2, 3, 7, 8, 12, 13, 17 and 18. The nitrogen atoms are numbered 21 through 24. Owing to the continued use of trivial names, both in the IUPAC and classical systems of nomenclature, certain other features of porphyrin notation and isomerism need to be explained. If the eight peripheral substituents are made up of two sets of four (for example, four methyls and four ethyls), and if there is one of each on the individual pyrrole subunits (a situation which usually occurs in biologically derived porphyrins), then there are four possible so-called primary type isomers. These four isomers for the methyl/ethyl series, trivially named etioporphyrins, are shown in Scheme 1 the compounds are named etioporphyrin-I (14), etioporphyrin-II (15), etioporphyrin-III (16), and etioporphyrin-IV (17). 

We will base our study on the system developed by the International Union of Pure and Applied Chemistry. The system is called the IUPAC Rules. There are other semi-systematic nomenclature systems, and many individual compounds are known by nonsystematic or trivial names. These names will be given along with the IUPAC names when such trivial names are commonly used. 

The nomenclature system commonly in use is known as the IUPAC Rules. These rules are as follows ... 

The IUPAC rules are not the only nomenclature system in use today. Chemical Abstracts Service surveys all the world s leading scientific journals that publish papers relating to chemistry and publishes brief abstracts of those papers. The publication Chemical Abstracts and its indexes are absolutely essential to the practice of chemistry. For many years Chemical Abstracts nomenclature was very similar to IUPAC nomenclature, but the tremendous explosion of chemical knowledge has required Chemical Abstracts to modify its nomenclature so that its indexes are better adapted to computerized searching. This means that whenever feasible, a compound has a single Chemical Abstracts name. Unfortunately, this Chemical Abstracts name may be different from any of the several IUPAC names. In general, it is easier to make the mental connection between a chemical structure and its IUPAC name than its Chemical Abstracts name. 

Although epoxides are always considered to have their oxygen atom as part of a three-membered ring, the prefix epoxy in the IUPAC system of nomenclature can be used to denote a cyclic ether of various sizes. Thus... 

Systematic nomenclature (Section 2.11) Names for chemical compounds that are developed on the basis of a prescribed set of rules. Usually the IUPAC system is meant when the term systematic nomenclature is used. 

Since the new IUPAC recommendations [5], the nomenclature of quinic acid isomers is very confusing in the literature. Therefore, the latest IUPAC nomenclature is used throughout this paper instead of the older, but still useful, nomenclature. In the IUPAC nomenclature quinic acid is now treated as cyclitol. In the preferred configuration, the carboxy group and the C-4 and C-5 hydroxy groups are equatorial, with the C-l and C-3 hydroxy groups are axial. In the IUPAC system, the former 3-O-acylquinic acids are now renamed 5-O-compounds, and the... 

Bridging Nomenclature for Use with Fused Systems (IUPAC Rules... 

The most recent recommendations by IUPAC for naming heterocyclic skeletons include only a small number of basic nomenclature systems, and, as a consequence of its need to provide unique names, the number of systems employed by Chemical Abstracts is even smaller. Of the systems now to be outlined, most are described in detail in the Appendix (to which reference is made where appropriate) the following text will cover only the general principles involved. Many of the systems are modifications of those used for carbocycles. 

For each of the nomenclature systems recommended here, correct numberings are obtained by application of elaborate series of priorities. These are set out clearly in the IUPAC Rules (Appendix), and no useful purpose would be served by a further detailed description. Their use is illustrated in many of the examples given here. However, the following points deserve some emphasis or further explanation. 

Systematic nomenclature on a worldwide scale began in 1892 when a committee of the International Chemical Congress established a set of standards known as the Geneva Rules for naming organic compounds. The International Union of Pure and Applied Chemistry (ILTPAC) http /Ywww,iupac.org/dhtml home.html was formed in 1919 and further developed this nomenclature system. In 1886 in the United States, the American Chemical Society (ACS) established a Committee on... 

The IUPAC nomenclature system for other types of compounds is given in Chapter 7 and is based on the fundamental rules described in this chapter. 

The saccharides have long and awkward names by the IUPAC system, consequently a highly specialized nomenclature system has been developed for carbohydrates. Because this system (and those like it for other natural products) is unlikely to be replaced by more systematic names, you will find it necessary to memorize some names and structures. It will help you to remember the meaning of names such as aldopentose and ketohexose, and to learn the names and details of the structures of glucose, fructose, and ribose. For the rest of the carbohydrates, the nonspecialist needs only to remember the kind of compounds that they are. 

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. 

An alternate nomenclature system based upon IUPAC principles polymer systems has also been developed but it has not been adopted broadly. Using this method, 15-crown-5 would be called cyclo[pentakis(oxyethylene)] instead of 1,4,7,10,13-pentaoxacyclopen-tadecane. In this case, substituents and other heteroatoms make the names more complex. 

---