As nomenclature

A nomenclature or notation is called unambiguous if it produces only one structure. However, the structure could be expressed in this nomenclature or notation by more than one representation, all producing the same structure. Moreover, uniqueness" demands that the transformation results in only one - unique -structure or nomenclature, respectively, in both directions. 

Thus, we see that we have not felt the need for a nomenclature factor in the first reaction shown in Figure 3-22, for the sole reason that the nomenclature factor has a value of (-f-1 ). 

Just as It makes sense to have a nomenclature system by which we can specify the con stitution of a molecule m words rather than pictures so too is it helpful to have one that lets us describe stereochemistry We have already had some experience with this idea when we distinguished between E and Z stereoisomers of alkenes... 

Fig. 9. Control valve and actuator (a) nomenclature (b) fail-open (F/O) or air-to-close (A/C) action and (c) fail-closed (F/C) or air-to-open (A/O)...

To determine the reasonableness of the top and bottom compositions of a fractionation column, a Hengstebeck plot is fast and easy (Reference 4). First, select a heavy key component and determine the relative volatility (a) of all column components to the heavy key. The a can be otfeed or perhaps more accurately cc = (a,op oCboitom) - Plot In D/B versus In a and the component points should fall close to a straight line. If a fairly straight line does not result, the compositions are suspect. A nomenclature table is provided at the end of this chapter. 

In Table 1, drawn up by the author, of abbreviations in common use those in bold type are in the main schedule of BS 3502. In this list the names given for the materials aie the commonly used scientific names. This situation is further complicated by the adoption of a nomenclature by the International Union of Pure and Applied Chemistry for systematic names and a yet further nomenclature by the Association for Science Education which is widely used in British schools but not in industry. Some examples of these are given in Table 2. Because many rubbery materials have been referred to in this book. Tables 3 and 4 list abbreviations for these materials. 

The Commission on Macromolecular Nomenclature of the International Union of Pure and Applied Chemistry has published a nomenclature for single-strand organic polymers Pure and Applied Chemistry, 48, 375 (1976)). In addition the Association for Science Education in the UK has made recommendations based on a more general lUPAC terminology, and these have been widely used in British schools. Some examples of this nomenclature compared with normal usage are given in Table 2. 

At the end of this chapter you will find four annexes. The first is a list of important terms and their definitions. These terms will help to orient you to discussions in later chapters. Next you will find a Nomenclature section that defines all the... 

A fluonnated dimethyl ether is assigned the same number as the corresponding Cj alkane prefixed with an "E , a nomenclature recently adopted by the National Institute of Science and Technology (NIST) in the United States... 

He suggested a nomenclature for the terpenes by which those compounds which contain a double linkage between the nucleus and the side chain should be called pseudo-compounds, whilst the compounds with the double linkage in the nucleus should be the ortho-compounds. He suggested the following formulae —... 

Appendix A Nomenclature of Polyfunctional Organic Compounds A-1 Appendix B Acidity Constants for Some Organic Compounds A-8 Appendix C Glossary A-10 Appendix D Answers to In-Text Problems A-30... 

Porphyrins are formally derived from the porphin (1) nucleus by substitution of some or all peripheral positions with various side chains. In the classical system of nomenclature T, introduced by H. Fischer,Sc the peripheral /5-pyrrolic positions are numbered front 1 to 8 and the methine positions (also named meso positions) between the pyrrole rings are designated a, //, y, and 5. The rings are lettered clockwise A, B, C, and D. The classical nomenclature was in the past more and more displaced by a nomenclature which numbers all the carbon... 

The concept of expansion of the porphyrin macrocycle by formally inserting additional carbon atoms between the pyrrole rings was first considered and synthetically realized by LeGoff/ He also suggested a nomenclature for these macrocyclic systems using the word platyrin which... 

Plastomer, a nomenclature constructed from the synthesis of the words plastic and elastomer, illustrates a family of polymers, which are softer (lower hexural modulus) than the common engineering thermoplastics such as polyamides (PA), polypropylenes (PP), or polystyrenes (PS). The common, current usage of this term is reshicted by two limitahons. First, plastomers are polyolehns where the inherent crystallinity of a homopolymer of the predominant incorporated monomer (polyethylene or isotactic polypropylene [iPP]) is reduced by the incorporahon of a minority of another monomer (e.g., octene in the case of polyethylene, ethylene for iPP), which leads to amorphous segments along the polymer chain. The minor commoner is selected to distort... 

A nomenclature was proposed by Seebach for the description of / -amino acids according to their substitution pattern, and for naming the resulting / -peptides [66, 67]. Enantiomerically pure / -amino acid derivatives with substituents in the 2-or 3-position are thus defined as - and / -amino acids, respectively (abbreviated to H-/ -HXaa-OH and H-/ -HXaa-OH). The corresponding /S-peptides built from these monomers will be named ff - and / -peptides. Similarly, /S -peptides consist of / -amino acid residues with substituents in both the 2- and 3-positions. Finally, peptides built from geminally disubsituted amino acids are referred to as and / -peptides (Fig. 2.6). 

The interfaces between a semiconductor and another semiconductor (e.g. the very important pin junction, the interface between p- and ft-type semiconductors), between a semiconductor and a metal (the Schottky barrier) and between a semiconductor and an electrolyte are the subject of solid-state physics, using a nomenclature different from electrochemical terminology. 

A Nomenclature—counts from carboxylate end. co Nomenclature—counts from methyl end. 

It is useful to introduce a nomenclature for distinguishing between ET occurring by the conduction and superexchange mechanisms. The term electron transport is used in the context of molecular wire behavior, while electron transfer is used in the context of the superexchange mechanism. 

The a-carbon of all amino acids, with the exception of glycine, has four different substituent groups and is therefore an asymmetric carbon atom. Such an atom can exist in two different spatial arrangements which are mirror images of each other. These structural forms of molecules are known as stereoisomers and the common notation of D and L forms is used, a nomenclature that refers to their absolute spatial configuration when compared with that of glyceraldehyde (Figure 10.4). 

The use of d- and L-prefixes is a nomenclature for orientation of atomic structure of sugar and amino acid molecules. It is a structural definition and is not related to the optical properties. 

The P-atom in sarin (9.84), soman (9.85), and tabun (9.87) is a stereogen-ic center, allowing for stereoselective enzymatic hydrolysis [162], This aspect has been extensively investigated for soman, which exists as four stereoisomers by virtue of the presence of a second stereogenic center (C-atom). These stereoisomers are usually designated as C(+)P(-), C(-)P(+), C(+)P(+), and C(-)P(-), where C(+/-) refers to the 1,2,2-trimethylpropyl moiety and P(+/ ) to the P-atom. Such a nomenclature may be convenient but has no implication for the absolute configuration. The C(+)P( ) and Cf-)P(-) epimers are the more active toward acetylcholinesterase and, hence, the more toxic ones. In contrast, the C(+)P(+) and C(-)P(+) epimers are preferentially hydrolyzed... 

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