Nomenclature IUPAC rules

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 IUPAC nomenclature rules. 

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. 

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

The advantageous chemical interaction capacities have led to a broad interest in silanes. The industrial production of a wide variety of organofunctional silanes has followed along. Despite of the great offer, ample use is restricted to few molecules. Those most commonly used silanes are listed in Table I. The names given are common names, which do not always follow IUPAC nomenclature rules. 

For purposes of clarity, we depart from the usual IUPAC nomenclature rules and place the unsaturated molecule at the end of the formula. 

The former groups 2A, 3A, 4A, 5A, and 6A have been redesignated, respectively, as groups 2, 13, 14, 15, and 16 in accordance with recent IUPAC nomenclature rules. 

The mesoionic l,3-dithiol-4-ones of type (2) are best represented as resonance hybrids of several limiting formulae (2a)-(2e), of which (2a) and (2b) are presumably most representative both formulae are, for example, in good agreement with the direction of the dipole moments. According to the IUPAC nomenclature rules, the mesoionic 1,3-dithiolones (2) should be named as l,3-dithiolylium-4-olates (B-79MI43202). 

In the now well-entrenched sub-discipline ("fiefdom") of natural products, Buckingham [21] advises "There is one major departure from recommended IUPAC nomenclature rules that is made by almost all those publishing in natural products... that each name shall have only one principal group." In other words, a major subset of "organic" chemists do not subscribe to the official nomenclature of their own domain, and a uniform... 

A significant fraction, however, of the documents in the scientific literature dealing with chemical entities and their biological effects are not composed of trivial names for the compounds under investigation. For the automated analysis of the chemical named entities in these publications, we need to use other methods. In principle, it should be possible to use rule-based approaches to identify IUPAC names (and other forms of IUPAC-like expressions), in particular, because the IUPAC name construction itself is based on rules. However, IUPAC names are neither unambiguous, nor can they easily be checked automatically for compliance with IUPAC nomenclature rules. In fact, most IUPAC-like expressions in patent literature seem to be not compliant with the IUPAC nomenclature, and cannot easily be converted into structures.40... 

Further explanations of the rules of organic nomenclature can be found online http //vvwv.acdlabs.com/iupac/nomenclature/ and in the following references... 

Ammonia and its inorganic and organic derivatives (HNR R2) couple readily with arenediazonium ions to give triazenes (Ar — N2—NR R2). Originally these compounds were called diazoamino compounds. Nowadays IUPAC nomenclature (IUPAC, 1979, Rule 942.2) recommends that the prefix diazoamino should be used only for compounds with the same organic residue at each end of the — N2 —NH — group. 

The diazoazido group is an unsaturated pentazano group. As it cannot be described by only one mesomeric formula, naming it according to the IUPAC nomenclature (1979, Rule 942.1) is difficult. Therefore we use diazoazide . 

IUPAC (1976) Rules for the Nomenclature of Organic Chemistry. Sect. E Stereochemistry. Pure Appl. Chem. 45, 11 [1.2]... 

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 IUPAC s standard nomenclature rules, structure 7 is named 3-ethyl-4-phenyl-2- 4-oxo-3-ethyl-5-[2-(3-ethyl-2,3-dihydro-benzo-l,3-thiazo-lylidene)ethylideneJ-tetrahydro-l,3-thiazoly]idene-metby] -1.3-thiazolium iodide (Scheme 5). It implies that the 4-phenyl thiazole ring having the... 

The majority of the names for chemicals in this alphabetically arranged index conform to one of the systematic series permitted under various sections of the IUPAC Definitive Rules for Nomenclature. Where there is a marked difference between these names and the alternative names recommended in the IUPAC-based BS2472 1983 or ASE 1985 nomenclature lists, or long established traditional names, these are given as synonyms in parentheses after the main title. These synonyms also have their own index entry, cross-referenced back to the IUPAC-based names used as bold titles in the text of Volume 1. 

It is recommended in rule E of the IUPAC nomenclature that RS be used when the compound in question is a racemate. Then the conformations — sc(R)... 

IUPAC Tentative Rules for the Nomenclature of Organic Chemistry. Section E. Fundamental Stereochemistry. J. Org. Chem., 1970, 35, 2849. 

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/).

The IUPAC nomenclature will be used in this book with some exceptions. One exception is the use of well-established, non-IUPAC names for most of the commonly encountered polymers of commercial importance. Another exception will be in not following rule 2 for writing the constitutional repeating unit (although the correct IUPAC name will be employed). Using the IUPAC choice of the CRU leads in some cases to structures that are longer and appear more complicated. Thus the IUPAC structure for the polymer in Eq. 1-3 is... 

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. 

According to IUPAC Nomenclature of Organic Chemistry, Rule C-331.1 ... 

IUPAC, Nomenclature of Inorganic Chemistry Definitive Rules 1970 , 2nd edn., Butterworths, London, 1971 Pare... 

IUPAC, Nomenclature of Organic Chemistry , 1979 edn., Rule C-22, Pergamon Press, Oxford, 1979, p. 112. 

An additional feature of IUPAC nomenclature that concerns the direction of numbering is the first point of difference rule. Consider the two directions in which the following alkane may be numbered ... 

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. 

A single alkane may have several different names a name may be a common name, or it may be a systematic name developed by a well-defined set of rules. The most widely used system is IUPAC nomenclature. Table 2.6 summarizes the rules for alkanes and cycloalkanes. Table 2.7 gives the rules for naming alkyl groups. 

IUPAC nomenclature (Section 2.11) The most widely used method of naming organic compounds. It uses a set of rules proposed and periodically revised by the International Union of Pure and Applied Chemistry. 

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