Methods of nomenclature

Before discussing the chemistry and technology of silicone polymers it is necessary to consider the methods of nomenclature of the silicon compounds relevant to this chapter. The terminology used will be that adopted by the International Union of Pure and Applied Chemistry. 

The literature in this field is confusing because of a somewhat haphazard method of nomenclature that has arisen historically. This is compounded by some mistakes in structure determination, reported in early papers, and which are occasionally quoted. The first part of this chapter deals with nomenclature and with a brief overview of early work. Subsequent sections deal with the formation and metabolism of di-D-fructose dianhydrides by micro-organisms, and the formation of dihexulose dianhydrides by protonic and thermal activation. In relation to the latter topic, recent conclusions regarding the nature of sucrose caramels are covered. Other sections deal with the effects of di-D-fructose dianhydrides upon the industrial production of sucrose and fructose, and the possible ways in which these compounds might be exploited. An overview of the topic of conformational energies and implications for product distributions is also presented. 

Recently, a new method of nomenclature of TPEs was produced jointly by the International Organization for Standardization (ISO), the Society of Automotive Engineers (SAE), the Association of the Automotive Industries (VDA), Germany, and the producers of raw materials. Nevertheless, for this chapter the above-mentioned abbreviations for the TPEs have been utilized. Table 5.3 provides a list of significant suppliers of different generic classes of TPEs with respective trade names. 

Since the adoption of this method of nomenclature for the steroids, the same method has been used with other classes of compounds — for example, the triterpenes (4). 

The nomenclature rules to be presented follow in the main the 1957 report of the Committee on Inorganic Nomenclature of the International Union of Pure and Applied Chemistry. The discussion here will be brief, and the methods of nomenclature of heteropoly acids, intermetallic compounds, unusual oxygen acids, isotopically enriched compounds, and silane derivatives will not be described. 

Early chemists routinely gave trivial names to substances before understanding their chemical structure and behaviour. This situation changed during the mid- to late-1800s. By this time, chemistry was firmly established as a science. Chemists observed and discovered new patterns of chemical relationships (such as periodicity). As well, chemists discovered new chemical compounds with tremendous frequency. The rapidly increasing number of chemical compounds required a more organized method of nomenclature. 

The Geneva system is a method of nomenclature which does not have this disadvantage since it is applicable to even the most complex hydrocarbons. To use this method it is first necessary to pick out the longest continuous chain of carbon atoms in the molecule and number them consecutively. The compound is considered to be a derivative of this longest continuous chain hydrocarbon. The various alkyl groups attached to this chain are named in the usual manner and their position is indicated by the number of the carbon atom to which they are joined. For example, for isopentane, there are four carbons in a... 

In tropone, 6ir electrons are reacting, and in the alkene, 4tt electrons are reacting. Therefore, if this is a concerted reaction, it also could be called a [6 + 4] cycloaddition. If the distinction is made that [6 + 3] refers to the cycloadduct and [6 + 4] refers to the cycloaddition, the two methods of nomenclature are compatible. However, this distinction is not always made in the literature, and unless one thinks about the details of the particular reaction, the descriptions may be confusing. 

A uniform method of nomenclature for all azo-compounds is much to be desired, but the strict application of such a principle, further than formation into groups, would lead to the necessity for very long, and often unwieldy names, without insuring certainty in regard to position. 

This is an alternative method of nomenclature, but one that is less easily interpretable in terms of structure than the hydrogen nomenclature. The name consists of two words, the second always being acid . The name gives the number of oxygen atoms attached to the central atom, the identity of the central atom and (usually) the oxidation state of the central atom. The first word in the name always ends in -ic , in contrast to traditional usage of -ic or -ous . Selected examples are listed in the table ... 

This method of nomenclature is called systematic nomenclature. It is also called lUPAC nomenclature because it was designed by a commission of the International Union of Pure and Applied Chemistry (abbreviated lUPAC and pronounced eye-you-pack ) at a meeting in Geneva, Switzerland, in 1892. The lUPAC mles have been continually revised by the commission since then. Names such as isobutane and neopentane—nonsystematic names—are called common names and are shown in red in this text. The systematic or lUPAC names are shown in blue. Before we can understand how a systematic name for an alkane is constructed, we must learn how to name alkyl substituents. 

The names of compound substances were formerly chosen upon the same system, or rather lack of system, as those of the elements. So long as the number of compounds with which tlie chemist had to deal remained small, the use of these fanciful appellations, conveying no more to the mind than perhaps some unimportant quality of the substances to which they applied, gave rise to comparatively little inconvenience. In these later days, however, when the number of compounds known to exist, or whose existence is shown by approved theory to be possible, is practically infinite, some systematic method of nomenclature has become absolutely necessary. 

The nylons are named by the number of carbon atoms in the repeat units. The materials formed by polymerizations of lactams therefore carry only one number in their names like, for instance, nylon 6 that is formed from caprolactam. By the same method of nomenclature, a nylon prepared by condensing a diamine with a dicarboxylic acid like, for example, hexamethylene diamine with adipic acid, is called nylon 6,6. It is customary for the first number to represent the number of carbons in the diamine and the second number to represent the number of carbons in the diacid. 

Because aromatic chemistry developed in a haphazard fashion many years before systematic methods of nomenclature were developed, common names have acquired historic respectability and are accepted by lUPAC. Examples include ... 

The physical and chemical properties of metacyclophanes, including some structures containing heteroaromatic rings, have been reviewed and new methods of nomenclature in this field have been suggested. Purification of a number of macroheterocycles of type (459) and their copper derivatives by vacuum sublimation are also reported. The bisdiansa-com-pound (461) of 5-aminobenzodioxol has been synthesized starting with... 

The large number of organic compounds requires a systematic method of nomenclature that can differentiate between subtle structural features. We will use the nomenclature system recommended by the International Union of Pure and Applied Chemistry (lUPAC), which has become standard. 

Many organic compounds are given COMMON or TRIVIAL names. However, as the number of carbon atoms in a molecule increases, the possibilities for isomerism increase. For example, there are 9 isomers for heptane, and 18 for octane. It would be obviously foolhardy to attempt to give each isomer an unambiguous trivial name. Chemists have developed a method of nomenclature that assigns a systematic, unique name to each possible compound. The system presently used is called the lUPAC system. 

An abbreviated method of nomenclature is to use a three letter designation or symbol for a monosaccharide and suffix/ or p for furanose or pyranose. For example, saccharose and maltose... 

This method of nomenclature is called systematic nomenclature. It is also called lUPAC nomenclature because it was designed by a commission of the International Union of Pure and Applied Chemistry (abbreviated lUPAC and pronounced eye-you-pack ) in 1892. 

Because the steroid ring system is rigid, functional groups bonded to ring atoms have well-defined positions. Substituents below the plane of the ring are designated as a those above the plane of the ring are P. We recall that down and up in substituted cyclohexane compounds are not synonymous with equatorial and axial. For the same reasons, this method of nomenclature for steroids does not indicate whether the substituent is equatorial or axial. 

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