Non-systematic names

Most fatty acids have an even number of carbon atoms, so none are left over after /3-oxidation. Those fatty acids with an odd number of carbon atoms yield the three-carbon propionyl CoA in the final j3-oxidation. Propionyl CoA is then converted to succinate by a multistep radical pathway, and succinate enters the citric acid cycle (Section 29.7). Note that the three-carbon propionyl group should properly be called propnnoyl, but biochemists generally use the non-systematic name. 

Like poly(ethylene), there are formal problems with the nomenclature of this polymer, since its lUPAC name, poly(propene), is also rarely if ever used hy polymer chemists. Since, in practice, no ambiguity is associated with the non-systematic name, this is the one that is generally used, as it will he throughout this hook. 

Both of these forms of representation are symbohc although words are more familiar symbols to students. Both of these forms present difficulties to learners. Although word equations may seem a more direct way for novices to represent chemical reactions, they may sometimes make more demands on learners. So, for example in completing equations, non-systematic names - such as ammonia - may not provide strong clues to the elements present, and there is a need to learn, recall and apply such rules as -ate implies oxygen present, etc. 

The 1,3,5-triazines are amongst the oldest known organic molecules. Originally they were called the symmetric triazines, usually abbreviated to s- or sym- triazines. The numbering follows the usual convention of beginning at the heteroatom as shown for the parent compound 1,3,5-triazine (1). Rather non-systematic nomenclature is prevalent even in the current literature, because some of the compounds have been known for at least 150 years. The non-systematic names of some of the more important 1,3,5-triazines are listed in Table 1. The terms melamine, cyanuric acid and cyan uric chloride will be used throughout this chapter, and the term triazine will refer to 1,3,5-triazines only. In addition to the above names, 2,4,6-trialkoxy-l,3,5-triazines (2) are called cyanurates. Similarly, 1,3,5-trialkyl-1,3,5-triazines (3) are called isocyanurates. 

However, corrole (Fig. 2) represents a peculiar system and it is generally referred to with the non-systematic name which will also be used throughout this paper. 

The first four members of many homologous series often have trival or non-systematic names, many dating back to the early history of chemistry, but from then on they have more systematic names which show how many carbon atoms there are present eg n = 5 is pentane, ( pent meaning five in Greek). Hex means six in Greek, so = 6 = hexane. 

In Example 12, the name [60]fullerene is to be regarded as an acceptable non-systematic name for a particular C6o structure. For more details see Section P-27 of Ref. 6. 

An abbreviation for an organic ligand should be derived from a name consistent with the current rules for the systematic nomenclature of organic compounds.4 (For some ligands a non-systematic name is included in Table VII if it was the source of the abbreviation and if that abbreviation is still commonly used.) New abbreviations should further be constructed according to the following recommendations ... 

A few cations have established and still acceptable non-systematic names. 

In a few cases, non-systematic names are still acceptable alternatives. 

This list is exhaustive as far as non-carbon parent hydrides are concerned. A number of established shortened or entirely non-systematic names are also used for carbon-based hydrides methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, phenyl, naphthyl, etc. 

The first transition element compound containing only carbocyclic rings as ligands was bis(ri5-cyclopentadienyl)iron, [Fe(r 5-C5H5)2], which has a sandwich structure with two parallel p5- or Ji-bonded rings. The recognition that this compound was amenable to electrophilic substitution, similar to the aromatic behaviour of benzene, led to the suggestion of the non-systematic name ferrocene and to similar names for other metallocenes . 

Ending of certain acceptable non-systematic names of unsaturated cyclic parent hydrides, e.g. benzene, azulene. 

Ending of some acceptable non-systematic names of heteropolyatomic anions cyanide, hydroxide. 

Ending of certain non-systematic names of oxidometal cations, e.g. vanadyl for oxidovanadium(2+). These names are no longer acceptable. 

The traditional, non-systematic names. Many of these linger on, especially for simpler or more common molecules. 

Each vegetable oil is characterised by its fatty acid composition which nevertheless may vary somewhat depending upon factors such as weather, soil conditions and variety. Typical fatty acid compositions of the most common vegetable oils, which together account for over 90% of world production, are given in Table 6.1 In the table, both non-systematic names and numerical notation are given, as an example, 18 2 refers to a fatty acid with 18 carbons and two double bonds. 

Non-systematic name and numerical representation Typical % fatty acid composition ... 

A salt-type nomenclature is frequently used with alkyl halides in which the alkyl group s name precedes the name of the halide. In addition, halogen derivatives of methane have familiar non-systematic names. 

The non-systematic name for the cycloheptatrienylium cation is the tropylium cation. 

Gunstone, F. D., and Adlof, R. O., Common (non-systematic) Names for Fatty Acids, www.aocs.org/member/division/analytic/fanames. asp, 2003. 

Some enzymes were named in the early days of the study of enzymes and have non-systematic names for example, the digestive enzymes pepsin, trypsin and ptyalin. 

Stage 2 Phenylamine (old, non-systematic name, aniline) is formed by the deprotonation of the phenylammonium ions using sodium hydroxide solution ... 

Biochemists know these two forms of butenedioic acid by different (non-systematic) names. Fumaric acid (trans-butenedioic acid) is an intermediate in the Krebs cycle, an essential part of aerobic respiration for energy release in cells (Chapter 15, and Chapter 23 on the accompanying website). Maleic acid (cis-butenedioic acid) is an inhibitor of reactions involved in the interconversion of amino acids in the liver. These different biological roles are a consequence of the molecules different shapes and their interactions with the enzymes involved in metabolic pathways. 

In naming compounds containing two or more chiral centres, attempts have been made to avoid partially systematic forms, frequently encountered in the literature, such as (25, 35H-) hydroxy-dtric acid . In the absence of further information, this can be misleading since it implies a numbering system for a non-systematically named compound (citric acid). We have pr eferred forms such as either (a) the systematic 2S,2Sy -) 3-carboxy-2,3-dihydroxyadipic acid or (b) the trivial (-)-hydroxydtric acid. 

Much of the early work on amphiphiles was undertaken on soaps and lipids based on fatty acids, and the corresponding non-systematic chemical names of these parent compounds and their derivatives are still commonly encountered. For convenience, Table 4.1 lists the systematic and trivial names of fatty acids, along with their structures. The names of derivatives are based on these for example sodium dodecyl sulphate is (still ) sometimes referred to as sodium lauryl sulphate. Other non-systematic names also exist to cause further confusion For example, hexadecyl (Cie chain) compounds are often termed cetyl derivatives. The use of the term fatty here and elsewhere is used to indicate an alkyl chain with 12 or more carbon atoms, i.e. a hydrocarbon that forms fats. 

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