Nomenclature Difficulties

The Stock Oxidation-Number System. Stock sought to correct many nomenclature difficulties by introducing Roman numerals in parentheses to indicate the state(s) of oxidation, eg, titanium(II) chloride for TiCl2, iron(II) oxide for FeO, titanium(III) chloride for TiCl, iron(III) oxide for Fe203, titanium(IV) chloride for TiCl, and iron(II,III) oxide for Fe O. In this system, only the termination -ate is used for anions, followed by Roman numerals in parentheses. Examples are potassium manganate(IV) for K2Mn02, potassium tetrachloroplatinate(II) for K PtCl, and sodium hexacyanoferrate(III) for Na3Fe(CN)3. Thus a set of prefixes and terminations becomes uimecessary. 

The Stock Oxidation-Number System. Stock sought to correct many nomenclature difficulties by introducing Roman numerals in parentheses to indicate the s(ate(s) of oxidation. 

An extensive Dictionary of Organophosphorus Compounds (compiled by R. E. Edmundson) was pnblished in 1988, and has been updated as part of the CRC database (see Section 1.2.1). It gives an extensive selection of alternative names. Substructure searching to locate compounds of analogons strnctnre can often resolve nomenclature difficulties for the commoner types. Organoarsenic nomenclature is analogous. 

Some of the species of the section Miltantha Bernh. differ morphologically. The external habitat and the form of growth of P. polychaetum and P. li-banoticum are unlike those of the other species. Nomenclatural difficulties also exist, particularly for chemists. 

Likewise, the nomenclature of neocyanines would not present any more difficulties if these suggested rules were followed, but it is not our task to apply them until official nomenclature is modified. 

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. 

This polymer has one of the simplest molecular structures ([CH2CH2— ] ) and is at present the largest toimage plastic material, having first been produced commercially in 1939 for use in electrical insulation. There is a difficulty over the nomenclature of this polymer. The lUPAC recommended name for the monomer is ethene, rather than the older ethylene. Hence the lUPAC name for the polymer is poly (ethene). However, this name is almost never used by chemists working with the material throughout this book, therefore, this polymer will be referred to by its more widespread name, poly(ethylene). 

A study of the nomenclature problem indicates that only samples are analyzed elements, ions, and compounds are identified or determined. The difficulty occurs when the sample is nominally an element or compound (of unknown purity). Analysis of... (an element or compound) must be understood to mean the identification or determination of impurities. When the intent is to determine how much of such a sample is the material indicated by the name, assay is the proper word. ... 

A systematic nomenclature, besides correlating the above products, can remove the difficulties which have, in certain cases, been encountered on employing the trivial name of a branched-chain sugar in naming its derivatives. 7 9... 

A selection of carboxylic ester hydrolases (EC 3.1.1) of major or more-modest significance in xenobiotic metabolism is given in Table 2.5. The recommendations of the Enzyme Nomenclature Committee on the classification of esterases cannot be considered completely satisfactory, but, even after decades of debate, a more satisfactory classification system remains to be proposed [56] [57], The main difficulties with esterase classification have been summarized as follows [58],... 

First, the true physiological substrates of most esterases are unknown. It is, therefore, hardly practicable to systematically name esterases according to the recommendations of the Enzyme Nomenclature Committee [1], i.e., based on the definite (physiological) role of the enzyme. The difficulty is that the use of nonphysiological substrates during purification and in characterization assays does not contribute to discovering the physiological role of an enzyme. 

We shall note, that the difficulties arise precisely when modelling is to be applied to molecules involving transition metal atoms mainly of the second half of the first transition row. Moreover, even among the TMCs formed by these atoms the problems are not uniformly distributed the normal chemical nomenclature does not provide here an adequate classification. 

A remarkable reaction of the phospho group is its transfer onto carbon in the biosynthesis of the C—P bond (Fig. 6). Incidentally, this leads to a difficulty with nomenclature, because the group -P03H2, which is known to chemists as phosphono, is called phospho only when on a heteroatom (64), so the transfer changes its name Despite much ealier guessing from labeling patterns that phosphoenolpyruvate was the source of the C—P bond, it was only in 1988 (65, 66) that the enzyme responsible was isolated. The difficulty proved to be that the equilibrium favors phosphoenolpyruvate by about 2000-fold (67), so that assays only detected the enzyme in the direction contrary to biosynthesis evidently the biosynthesis takes place because subsequent reac-... 

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