Nomenclature for Chemical Compounds

Systematic nomenclature (Section 2 11) Names for chemical compounds that are developed on the basis of a prescnbed set of rules Usually the lUPAC system is meant when the term systematic nomenclature is used... 

In all cases the nomenclature adhered to is that used in the original memoirs, any alteration of which must be undertaken by an International Committee. For an author to make such alterations would merely mean that another set of names had been added to those already in existence, and would tend to add to the present confusion. The author, as in Volume II., again appeals to Chemical Societies to secure some definite standard nomenclature for organometallic compounds in general. 

Nomenclature, the naming system for chemical compounds, is summarized in Figures 11.4 and 11.5. Nomenclature for acids is not included in the chart. 

A detailed discussion of the nomenclature for heterocyclic compounds can be found in the first edition of Comprehensive Heterocyclic Chemistry (CHEC-I, Section 1.02). Some of the rules of systematic nomenclature used in Chemical Abstracts and approved by the International Union of Pure and Applied Chemistry are collected here. Important trivial names are listed at the beginning of individual chapters. 

The use of proper chemical nomenclature is essential for effective scientific communication. More than one million new substances are reported each year, each of which must be identified clearly, unambiguously, and completely in the primary literature. Chemical compounds are named according to the rules established by the International Union of Pure and Applied Chemistry (IUPAC), the International Union of Biochemistry and Molecular Biology (IUBMB) [formerly the International Union of Biochemistry (IUB)], the Chemical Abstracts Service (CAS), the Committee on Nomenclature, Terminology, and Symbols of the American Chemical Society, and other authorities as appropriate. For more information on naming chemical compounds, refer to the bibliography in Chapter 18. This chapter gives the editorial conventions and style points for chemical compound names. 

From the standpoint of nomenclature, inorganic chemical compounds may be divided into the following major divisions binary, ternary, and higher order. The development to date of nomenclature systems for each of these classes is summarized in the following statements ... 

Most students of chemical nomenclature will agree that a broad general pattern which is capable of extension to diverse types of compounds is preferable to a number of specific patterns of limited extension. Inasmuch as most compounds of higher order can and should be looked upon as coordination compounds, coordination compounds encompass an extremely broad field. The development of a satisfactory scheme of nomenclature for these compounds may solve many nomenclature problems. If coordination compounds represent a fundamental pattern of chemical combination, there should be a sound basic plan for the nomenclature of this broad class of compounds. 

The nomenclature for molecular compounds is much less complicated than for ionic compounds. Molecular compounds are formed from covalently bonded nonmetallic elements. The formula for a molecule represents a stable unit of atoms, unlike a formula for an ionic compound, which only represents the simplest whole number ratio of ions. As a result, molecular formulas cannot be simplified like formulas for ionic compounds. An example would be hydrogen peroxide, H O. Although the formula could be reduced to HO, this would be inappropriate because 11,0, is a molecule. Changing the structure to HO would change the chemical composition. 

The searcher should inform himself not only on scientific nomenclature and terminology, but also on popular usage and trade names. For chemical compounds, particularly complicated ones, all synonyms and correct and incorrect terms should be listed. It cannot be assumed that authors and indexes use orthodox terminology, especially where industrial or trade journals are involved. An inadequate knowledge of unscientific nomenclature and terminology is just as likely to cause a searcher to miss references as a lack of knowledge of proper nomenclature. 

Nomenclature of chemical compounds. Most undergraduate organic textbooks provide a more detailed account of die nomenclature used for organic molecules, including the R,S nomenclature for chiral centers. 

See the table Nomenclature of Chemical Compounds for references. The assistance of Warren H. Powell in preparing this list is gratefully acknowledged. 

Wiswesser line notation [46-48] is another important historical development in chemical notation that offered useful service in early searches for chemical compounds. More recent developments were more mathematical, based on suitable modifications of graph theoretical concepts. In the case of structurally related molecules, simple nomenclatures have been developed for benzenoid hydrocarbons by Balaban based on the concept of inner duals. In this approach, benzene rings are represented by single vertices that are connected if benzene rings have a common CC bond [26,49], Balaban and Schleyer extended the dualist graph principle to polymantane, which is bnilt from adamantane units superimposed on a diamond lattice [50,51]. 

The systematic lUPAC nomenclature of compounds tries to characterize compounds by a unique name. The names are quite often not as compact as the trivial names, which are short and simple to memorize. In fact, the lUPAC name can be quite long and cumbersome. This is one reason why trivial names are still heavily used today. The basic aim of the lUPAC nomenclature is to describe particular parts of the structure (fi agments) in a systematic manner, with special expressions from a vocabulary of terms. Therefore, the systematic nomenclature can be, and is, used in database systems such as the Chemical Abstracts Service (see Section 5.4) as index for chemical structures. However, this notation does not directly allow the extraction of additional information about the molecule, such as bond orders or molecular weight. 

The practice of assigning ad hoc names to organic compounds was neither avoidable, nor burdensome when only a small number of compounds were recognized. Such ad hoc names are termed "trivial" or "traditional," to indicate that they contain no encoded stmctural information. They are useful for common compounds, and many of them are retained to this day, but they are not helpful in understanding chemical relationships. As they proliferated, the number and variety of them became unmanageable. The development of systematic nomenclature was driven by this circumstance, and was made possible by advances in understanding and determining the stmcture of molecules. 

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