Important Representatives

The pigments are commonly referred to not only by their Colour Index name but also by an added abbreviation for the respective heteropoly acid. For instance  

CF represents copper ferrocyanide (copper-l-hexacyano-iron-II-acid). 

l 42595 2 PTM PM hnc2h5 c2h5 Victoria Pure Blue B (Basic Blue 26) 

Its coloristic properties make P.B.l a suitable and widely used colorant for special printing inks. The pigment may be incorporated without problems in oily binders, i.e., in letterpress and offset inks. It is equally often used in publication gravure printing inks based on toluene and in packaging printing inks based on NC. Problems which may arise as P.B.l is incorporated in these vehicles are mentioned under P.V.2. Besides, P.B.l lends color to paper, wallpaper, typewriter ribbons, and other media, although it is often difficult to disperse. 

At present, P.B.2 is only produced in the USA, where both PM and PT types are available. They are greener than grades of P.B.1. P.B.2 has much less impact on the market than P.B.1. 

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A general limitation of the relaxation teclmiques with small perturbations from equilibrium discussed in the previous section arises from the restriction to systems starting at or near equilibrium under the conditions used. This limitation is overcome by teclmiques with large perturbations. The most important representative of this class of relaxation techniques in gas-phase kinetics is the shock-tube method, which achieves J-jumps of some 1000 K (accompanied by corresponding P-jumps) [30, and 53]. Shock hibes are particularly... 

Carbohydrates may be divided into monosaccharides, disaccharides and polysaccharides. The monosaccharides under certain conditions react as polyhydroxy-aldehydes or polyhydroxy-ketones two important representatives are glucose CjHjjO (an aldose) and fructose (laevulose) CgHuO, (a ketose). Upon hydrolysis di- and polysaccharides 3deld ultimately monosaccharides. Common disaccharides are sucrose, lactose and maltose (all of molecular formula C,2H2. 0,), whilst starch, dextrin and cellulose, (CjHjoOj), in which n > 4, are typical polysaccharides. 

Many heterocyclic systems contain double bonds and are related to arenes The most important representatives of this class are described m Sections 11 22 and 11 23... 

LC polyesters belong to the class of thermotropic main-chain LCPs, which also comprises polymers such as polycarbonates, polyethers, polyphenylenes, polyester-imides, polymers containing azo- or azo V-oxide linking groups, some cellulose derivatives, and polypeptides such as po 1 y (y - be n zy 1 -1. - g 1 u tamate). Both from the academic and industrial points of view, polyesters are by far the most important representatives of this class of polymers. 

The structural range of industrially important representatives of these groups is enormous, and includes chlorobenzenes (solvents), polychlorinated biphenyls (PCBs) (hydraulic and insulating fluids), and polybrominated biphenyls and diphenyl ethers (flame retardants). There is widespread concern over both the persistence and the potential toxicity of all these compounds, and sites that have become contaminated during their production represent a threat both to the environment and to human health. Pathways for the aerobic bacterial degradation of chlorobenzenes and chlorobiphe-nyls, and their brominated analogs have been discussed in Chapter 9, Part 1. 

Glass electrode [see Fig 2.10 (1)J. The pH glass electrode, as the most important representative of the glass electrodes, will be the first subject to be treated, and especially in its application to aqueous solutions. Attached to the stem of high-resistance glass, the electrode proper consists of a pH-sensitive glass bulb that acts as a membrane between an inner reference electrolyte and an outer... 

The net reaction is the transfer of C02 at a rate close to 1 mole per 2 Faradays, and the production of water. The process is quite complex the detailed analysis showed that cathode-side, gas-phase mass transfer of C02 was totally controlling only at the lowest C02 levels and high current densities. At other conditions chemical reaction rates and transport through the membrane became important representative results... 

The "classic" molecule is M02(C CCHa), which is an important representative member of di-metal molecules containing a quadruple bond. The occupation of the delta-bonding orbital, which completes formation of the quadruple bond, is a special feature of these molecules. The classic question is the following To what extent does an electron in the delta-bonding orbital contribute to the total bond strength and force constant between the two metal centers ... 

The insecticides and miticides mentioned are not the only ones known to be effective against cotton pests, but they include most of those used for that purpose in the United States. Many of them are imported in considerable quantities into Latin American countries and have proved their effectiveness there. Approximately 44,000,000 pounds of technical organic insecticides (DDT, BHC, toxaphene, aldrin, dieldrin, parathion, etc.), 3,600,000 pounds of calcium arsenate, and 82,000 pounds of nicotine sulfate were exported from the United States to these countries during 1953. Some insecticides are exported from Europe, particularly Folidol (methyl parathion) from Germany. Even though these imports represent considerable quantities of insecticides, they are still far short of the minimum needs for adequate cotton-pest control. 

Only a few important representatives of the non-proteinogenic amino acids are mentioned here. The basic amino acid ornithine is an analogue of lysine with a shortened side chain. Transfer of a carbamoyl residue to ornithine yields citrulline. Both of these amino acids are intermediates in the urea cycle (see p.l82). Dopa (an acronym of 3,4-dihydroxy-phenylalanine) is synthesized by hydroxyla-tion of tyrosine. It is an intermediate in the biosynthesis of catecholamines (see p.352) and of melanin. It is in clinical use in the treatment of Parkinson s disease. Selenocys-teine, a cysteine analogue, occurs as a component of a few proteins—e.g., in the enzyme glutathione peroxidase (see p.284). 

Adhesive proteins provide the connections between the various components of the extracellular matrix. Important representatives include laminin and fibronectin (see B). These multifunctional proteins simultaneously bind to several other types of matrix component. Cells attach to the cell surface receptors in the ECM with the help of the adhesive proteins. 

Neurotransmitters can be classified into several groups according to their chemical structure. The table lists the most important representatives of this family, which has more than 100 members. 

There is an extremely large number of cytokines only the most important representatives are listed opposite. The cytokines include interleukins (IL), lymphokines, monokines, chemokines, interferons (IFN), and colony-stimulating factors (CSF). Via interleukins, immune cells stimulate the proliferation and activity of other immune cells (see p. 294). Interferons are used medically in the treatment of viral infections and other diseases. 

The short-acting sulfonamides include sulfadimidine, sulfamerazine and sulfathiazole. Sulfadimidine, as the most important representative of this group, is relatively soluble and has therefore a lower risk of causing crystalluria while sulfamerazine and sulfathiazole are less soluble sulfonamides. Sulfadimidine has good oral absorption. It has an elimination half-life between 1.5 and 5 hours, depending on acetylator phenotype. 

Apart from the salicylates NSAIDs include several classes of weak acids like propionic acid derivatives such as ibuprofen, carprofen, fenbufen, fenoprofen, flurbiprofen, ketorolac, loxoprofen, naproxen, oxaprozin, tiaprofenic acid and suprofen. Phenylbutazone is the most important representative of the pyrazolon derivatives which have a bad reputation for their risk of potentially fatal bone-marrow toxicity. To the acetic acid derivatives belong in-domethacin, diclofenac and sulindac. Sulindac is a pro-drug with less toxicity than indomethacin. The enolic acids include piroxicam, droxicam and tenoxicam. Meloxicam is an analog of piroxicam and has a high selectivity for COX-2. 

The first antitumor antibiotic was actinomycin A which was isolated from a Streptomyces species. The actinomycins are chromopeptides containing a planar chromophore, responsible for the bright color of the compounds, with peptide side chains. The most important representative of this group which is in clinical use is actinomycin D, or dactinomycin. 

The dehydroamino acids or esters obtained have been used as intermediates to prepare a diverse array of interesting compounds and some important, representative examples are described in the following sections. 

The field of natural raw materials is dominated by plant derivatives. Important representatives of naturals are the botanical extracts. Extracts can be obtained by water or alcohol-water extraction. Onion extract, for example, is produced by squeezing the washed and ground onion bulbs in large filter presses. The resulting onion juice can then be concentrated to give a stable raw onion extract with superior flavour properties. A valuable by-product is the onion oil which... 

The list of the new gels for which phase transitions are possible is supplemented in the paper by Amiya and Tanaka, who discovered discrete collapse for the most important representatives of biopolymers - chemically crosslinked networks formed by proteins, DNA and polysaccharides [45]. Thus, it was demonstrated that discrete collapse is a general property of weakly charged gels and that the most important factor, which is responsible for the occurrence of this phenomenon, is the osmotic pressure of the system of counter ions. 

Heterocycles structurally based on the phenalene ring system frequently possess distinctive colors. With nitrogen as the central atom we have the unstable 9a-azaphenalene (20), (76JCS(Pl)34i). The cyclazine nomenclature is commonly applied to this and related compounds thus, (20) is (3.3.3)cyclazine. Further aza substitution is possible, e.g. as in the heptaazaphenalene (21). Another well-known and important representative of this family is yellow colored perimidine. 

The commercially important representatives of group 4 are diphenyl guanidine and diortho tolyl guanidine. Group 5 includes a number of aldehyde aniline reaction products such as formaldehyde aniline, ethyledene aniline, butraldehyde aniline, heptaldehyde aniline hexa methylenetetraamine and acet-aldehydeaniline. Aetaldehyde, butraldehyde and heptaldehyde derivatives of aromatic amines are powerful accelerators. 

In bacteria, primary glycosyl nucleotides include14 22 UDP-Glc, as well as other nucleotide derivatives of the same monosaccharide. Important representatives of this class are16"21,23"25 dTDP-Glc and17"19,21,26 29 CDP-Glc, which serve as precursors for a number of secondary glycosyl nucleotides, whereas similar enzymic reactions have not been demonstrated for GDP-Glc,1819,21,30 and ADP-Glc17 19,21-31"38 seems to participate only in the biosynthesis of bacterial glycogen, a subject that is beyond the scope of this article. 

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