Nomenclature rules

Rhodacyanines possess two chromophoric systems. They are at the same time neutrocyanine derivatives, which involves position 5 of the ketomethylene, and methine cyanine, which involves position 2. Following lUPAC s standard nomenclature rules, structure 7 is named 3-ethyl-4-phenyl-2- 4-oxo-3-ethyl-5-[2-(3-ethy]-2,3-dihydro-benzo-l,3-thiazo-lylidene)ethylidene]-tetrahydro-l,3-thiazolylidene-methyl -1.3-thiazolium iodide (Scheme 5). It implies that the 4-phenyl thiazole ring having the... 

For purely alicyclic compounds, the selection process proceeds successively until a decision is reached (a) the maximum number of substituents corresponding to the characteristic group cited earliest in Table 1.7, (b) the maximum number of double and triple bonds considered together, (c) the maximum length of the chain, and (d) the maximum number of double bonds. Additional criteria, if needed for complicated compounds, are given in the lUPAC nomenclature rules. 

Implicit ia the base names are the absolute configurations at carbons 8 and 12 and the iadicated numbering systems. Derivatives of these parent stmctures are named according to terpene and steroid nomenclature rules (see Steroids Terpenoids). The lengthy and awkward nature of the chemical abstract systematic nomenclature (12) for these compounds has resulted ia the development (13) and use of simplified nomenclature based on common names. 

In the present review the carboline, rather than the pyridoindole, nomenclature is adopted with the numbering for a-, jS-, y-, and S-carbolines shown in structures 5-8, respectively, as recommended by the Editor of the Journal of the Chemical Society in his Report on Nomenclature, 1952, ° and by the Definitive I.U.P.A.C., 1957, rules of organic nomenclature (Rule B—2.11). In the interest of clarity. 

A summary of nomenclature rules for carboxylic acid derivatives is given in Table 21.1. 

Some 117 naturally occurring apo-carotenoids, 88 of which have been fully identified and another 6 naturally occurring seco-carotenoids have been referenced as carotenoids, thus representing around 15% of the carotenoids numbered to date (see Figure 3.3.1). This subfamily of carotenoids would be even larger if we consider the retinoids andnorisoprenoids. However, these compounds are excluded by nomenclature rules that dictate that they are not deemed to be carotenoids because of the absence of two central methyl groups (at C20 and C20 ). Retinoic acid, retinal. 

Some compounds, namely molecular compounds, contain only nonmetals. Normally the compounds you need to name are binary compounds (containing only two elements). If you have highlighted the metalloids on your periodic table, everything to the right of the metalloids is a nonmetal. The following rules apply to both nonmetals and metalloids. The only nonmetal excluded from these nomenclature rules is hydrogen. 

Many transition metals and the group of six elements centered around lead on the periodic table commonly have more than one valence. The valence of these metals in a compound must be known before the compound can be named. Modern nomenclature rules indicate the valence of one of these metals with a Roman numeral suffix (Stock notation). Older nomenclature rules used different suffixes to indicate the charge. Examples ... 

Since atropisomers are conformational isomers, their stereochemistry should be designated by IUPAC nomenclature rule E (23). For the convenience of the reader, the rule will be outlined here. A sequence number is given to substituents connected to the rotational axis according to the Sequence Rule (24), as follows. 

Fig. 6.1. IUPAC-IUB Commission on Biochemical Nomenclature rules defining residues and peptide units in peptides. In the example shown, residue No. 2 contains the backbone atoms N2, C2, and C2. Peptide unit No. 2 contains the backbone atoms C2, C2, and Nf. Rj, R2, and R3 are the side chains of the amino acid residues (www.chem.qmul.ac.uk/iupac/AminoAcid/).

Mote recent books have been cited in the bibliography and may be useful to consult (8-19). Discussions of several stereochemical concepts are reported in the various editions of tire lUPAC nomenclature rules (20, 21). 

Structure-based and source-based nomenclature rules have been extended to regular double-strand (ladder and spiro) organic polymers [7]. A double-strand polymer is defined as a polymer the molecules of which are formed by an uninterrupted sequence of rings with adjacent rings having one atom in common (spiro polymer) or two or more atoms in common (ladder polymer). 

The largest main-chain (backbone) segment of the constitutional repeating unit that can be named as a single unit under organic nomenclature rules [4, 5], This may be a ring or ring system, a heteroatom or a heteroatom chain or an acyclic carbon chain. 

The subunits and substituted subunits, which are parenthesized or bracketed, are named by organic nomenclature rules [4,5] with the following exceptions ... 

The Commission acknowledges the first structure-based nomenclature rules for organic ladder and spiro polymers proposed by the Nomenclature Committee of the Division of Polymer Chemistry of the American Chemical Society [9]. 

Before proceeding one needs to mention Chemical Abstracts (CA), a journal published by the American Chemical Society, that abstracts the world s chemical hterature and has developed its own nomenclature rules. The CA rules are generally very close to the IUPAC rules, but there are some differences. Most of the differences are not important at the level of the discussions in this book. One difference that needs to be mentioned is the placement of locants. CA does not place locants immediately before the part of the name to which they apply. Thus, the CA name for the first subunit in XV is 2,4-pyridinediyl instead of pyridine-... 

The polymer is commonoly referred to as poly(dimethylsiloxane), but the IUPAC name is either poly(oxydimethylsilanediyl) or catena-poly[(diphenylsilicon)-p-oxo] depending on whether one uses the nomenclature rules for organic or inorganic polymers. The prefix catena refers to a linear polymer, not branched or crosslinked. 

The names of unsaturated compounds are derived by using appropriate substitutive nomenclature rules. Note that trivial names are also allowed for particular polynuclear species, for example, N2H4, diazane, commonly known as hydrazine. For a discussion of names of hydrides in which elements exhibit non-standard bonding numbers, see the Nomenclature of Inorganic Chemistry, p. 85. Note that for the hydrides of Table 5.1 and their derivatives, substitutive names are generally preferred. 

Despite the apparent clarity of the nomenclature rules, several papers in the area of the A-type proanthocyanidins still lack proper implementation of these rules. The reader must therefore ascertain the correctness of published names. In addition, the reader is also referred to the growing body of evidence of the physiological importance of these compounds, data of which can be found in several of the papers listed in the references. 

SELECTED IUPAC NOMENCLATURE RULES FOR N-ATOM POLYCYCLIC AROMATIC COMPOUNDS... 

Cis-trans isomerism is usually indicated by conventional nomenclature rules, although it must be pointed out that the literature mentions such geometric isomerism rarely. 

Scheme 2.1 Kinetic resolution of glycidyl butyrate catalyzed by porcine pancreatic lipase, PPL The preferential conversion of (S)-glycidyl butyrate into (R)-glycidol and butyric acid results from the stereochemical nomenclature rules under the Cahn, Ingold, Prelog convention, the configuration around the chiral centre is not affected.

For the practicing chemist, a working knowledge of present-day chemical nomenclature is indispensable. However, most chemists have neither the time nor the inclination to acquire the detailed knowledge of nomenclature rules that is essential for their correct application. To derive a unique systematic name for a complex chemical structure is an exercise requiring some intellectual agility the rules to be applied are often highly involved, and their correct interpretation is not always apparent. 

This article is an attempt to provide a guide to the nomenclature of heterocyclic compounds. The various systems available will be described, and problems associated with their use will be discussed. Where appropriate, the advantages and disadvantages of particular systems will be mentioned. In the interests of precision and conciseness, nomenclature rules themselves are not framed in a readily digestible form they are meant not for reading, but for reference. It is hoped that the following text will be more readily assimilable, and, in conjunction with the original rules (the most relevant of which are provided here as an Appendix), will enable the reader to name the majority of heterocyclic molecules. However, it is beyond the scope of the article to cover all possible heterocyclic structures in cases where the text proves inadequate, reference to the rules themselves will be necessary. 

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