Nomenclature Chemistry system

Enzymes are classified in terms of the reactions which they catalyse and were formerly named by adding the suffix ase to the substrate or to the process of the reaction. In order to clarify the confusing nomenclature a system has been developed by the International Union of Biochemistry and the International Union of Pure and Applied Chemistry (see Enzyme Nomenclature , Elsevier, 1973). The enzymes are classified into divisions based on the type of reaction catalysed and the particular substrate. The suffix ase is retained and recommended trivial names and systematic names for classification are usually given when quoting a particular enzyme. Any one particular enzyme has a specific code number based upon the new classification. 

In response to this nomenclature dilemma, the Cahn-Ingold-Prelog (IUPAC, International Union of Pure and Applied Chemistry) system of nomenclature was developed and is now the standard mediod to specify the relative configuration of chiral centers in molecules. Each chiral center will have two possible mirror-image configurations, which are designated as eidter R or S. 

When writing a chemical formula, you learned that you write the metal element first. Similarly, the metal comes first when naming a chemical compound. For example, sodium chloride is formed from the metal sodium and the non-metal chlorine. Think of other names you have seen in this chapter, such as beryllium chloride, calcium oxide, and aluminum oxide. In each case, the metal is first and the non-metal is second. In other words, the cation is first and the anion is second. This is just one of the rules in chemical nomenclature the system that is used in chemistry for naming compounds. 

To devise a system of nomenclature that could be used for even the most complicated compounds, committees of chemists have met periodically since 1892. The system resulting from these meetings is called the lUPAC (International Union of Pure and Applied Chemistry) system. This system is much the same for all classes of organic compounds. The lUPAC name for an organic compound consists of three component parts ... 

Today, there are several systematic nomenclatures but only two of them are so widely used that the average chemist is likely to encounter them with much frequency. One of these is the lUPAC (International Union of Pure and Applied Chemistry) system and the other is the CAS (Chemical Abstracts Service of the American Chemical Society) system. Both these organizations have numerous on-going committees and commissions to address both old and new problems in nomenclature. 

The lUPAC rules are not the only nomenclature system in use today Chemical Abstracts Service sur veys all the worlds 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 es sential to the practice of chemistry For many years Chemical Abstracts nomenclature was very similar to lUPAC 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 sin gle Chemical Abstracts name Unfortunately this Chemical Abstracts name may be different from any of the several lUPAC names In general it is easier to make the mental connection between a chemical structure and its lUPAC name than its Chemical Abstracts name... 

The nomenclature (qv) of polyamides is fraught with a variety of systematic, semisystematic, and common naming systems used variously by different sources. In North America the common practice is to call type AB or type AABB polyamides nylon-x or nylon-respectively, where x refers to the number of carbon atoms between the amide nitrogens. For type AABB polyamides, the number of carbon atoms in the diamine is indicated first, followed by the number of carbon atoms in the diacid. For example, the polyamide formed from 6-aminohexanoic acid [60-32-2] is named nylon-6 [25038-54-4], that formed from 1,6-hexanediamine [124-09-4] or hexamethylenediamine and dodecanedioic acid [693-23-2] is called nylon-6,12 [24936-74-1]. In Europe, the common practice is to use the designation "polyamide," often abbreviated PA, instead of "nylon" in the name. Thus, the two examples above become PA-6 and PA-6,12, respectively. PA is the International Union of Pure and AppHed Chemistry (lUPAC) accepted abbreviation for polyamides. 

Heteroeyeles structurally based on the phenalene ring system form an interesting elass, frequently possessing distinetive eolours. With nitrogen as the central atom we have the unstable 9b-azaphenalene (24), whieh has only fairly reeently been prepared and is still comparatively little studied (76JCS(Pl)34l). The cyclazine nomenclature is commonly applied to this and related compounds thus, (24) is (3.3.3)cyclazine. With further aza substitution, in positions alternant to the central atom, their stability increases the heptaazaphenalene (25) is (thermally) a very inert compound, derivatives of which, e.g. the triamine, have been known since the early days of organic chemistry (see Chapter 2.20). 

It is often the case that chemists involved or familiar with ethylene oxide (oxiran) chemistry refer to these cyclic oligomers as EO-4, EO-6 and EO-7 respectively. Such designations are informal if not colloquial but, like any name, are useful if they correctly convey an idea. The difficulty with these informalities, indeed with the crown nomenclature system is that it cannot adequately deal with complicated structures or even isomers of simple ones. 

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). 

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. 

UPAC system of nomenclature (Section 3.4) Rules for naming compounds, devised by the International Union of Pure and Applied Chemistry. 

IUPAC Commission on Nomenclature of Organic Chemistry, Revision of the extended Hantzsch-Widman system of nomenclature for heteromonocycles, Pure Appl. Chem., 55, 409-416 (1983). 

The nomenclature and numbering system adopted in this article is the one currently widely used in the literature and corresponds closely to the one suggested by Shaw (13,17). Only the chemistry of chlorocyclo-phosphazenes is dealt with in this review. The structural and bonding aspects are not considered here. 

In this chapter, as in CHEC(1984) and CHEC-II(1996) <1984CHEC(6)393, 1996CHEC-II(4)229>, the chemistry of compounds with the 1,2,5-oxadiazole ring system is considered. The history and nomenclature of these compounds, as well as basic synthetic methods and chemical properties of 1,2,5-oxadiazoles reported before 1996, were reviewed previously . This chapter covers the period from 1996 to 2006. 

---