Cations applications

Cobalamine 7i-cations, applications, 7, 48 Cobalamines, Co-C homolysis, 7, 35 Cobalamins, characteristics and reactions, 1, 884 Cobaloximes... 

Blais, J.-S., Huyghues-Despointes, A., Momplaisir, G.-M. and Marshall, W.D. (1991) High-performance liquid chromatography-atomic absorption spectromety interface for the determination of selenoniocholine and trimethylselenonium cations applications to human urine./. Anal. At. Spectrom., 6, 225-232. 

The great impact in metal-ion coordination chemistry caused by the discovery of the macrocyclic polyethers31 has led to new designs of chemosensors for the alkali cations. Application of a supramolecular receptor to fluorescence sensing was first... 

Depasse, J., Simple experiments to emphasize the main characteristics of the coagulation of silica hydrosols by alkaline cations Application to the analysis of the model of Colic et al., J. Colloid Intetf. Sci., 220, 174, 1999. 

Detection of physiological concentrations of Na" and in the presence of other monovalent cations. Applications are ... 

Comparison of the rJ values for the Na" " and K" " complexes of sallnomycin in Table I with the rJ values for sallnomycin anion in Figure 5 shows an increase In the magnitude of rJ upon complexatlon In all solvents. This corresponds to a change In conformation upon complexatlon, l.e. reorientation of the lonophore about the cation. Application of the Octant Rule to computer generated models of sallnomycin Indicates that this reorientation Is a constriction of the llgandlng oxygens which surround the cation. The extent of this constriction correlates with the stability of the complex indicated by Its Kjj (cf. Table I). 

Esaka, Y, Tanaka, K., Uno, B., and Goto, M. 1997. Sodium dodecyl sulfate Tween 20 mixed micellar electrokinetic chromatography for separation of hydrophobic cations Application to adrenaline and its precursors. AwaZ. Chem. 69 1332-1338. 

Donaldson, W. A. Preparation and Reactivity of Acyclic (Pentadienyl)iron(H-) Cations Applications to Organic Synthesis. Aldrichim. Acta 1997,30,17-24. 

A selection of important anionic surfactants is displayed in table C2.3.1. Carboxylic acid salts or tire soaps are tire best known anionic surfactants. These materials were originally derived from animal fats by saponification. The ionized carboxyl group provides tire anionic charge. Examples witlr hydrocarbon chains of fewer tlran ten carbon atoms are too soluble and tliose witlr chains longer tlran 20 carbon atoms are too insoluble to be useful in aqueous applications. They may be prepared witlr cations otlrer tlran sodium. 

The exchange resins 6nd application in (i) the purification of water (cation-exchange resin to remove salts, followed by anion-exchange resin to remove free mineral acids and carbonic acid), (ii) removal of inorganic impurities from organic substances, (iii) in the partial separation of amino acids, and (iv) as catalysts in organic reactions (e.g., esterification. Section 111,102, and cyanoethylation. Section VI,22). 

The superacid-catalyzed cracking of hydrocarbons (a significant practical application) involves not only formation of trivalent carbo-cationic sites leading to subsequent /3-cleavage but also direct C-C bond protolysis. 

For this series of compounds qualitative information is quite extensive. Application of the criteria discussed in 8.2, in particular comparison with the corresponding methyl quaternary salt, establishment of the rate profile for nitration in sulphuric acid, and consideration of the encounter rate and activation parameters, shows that 2,4,6-collidine is nitrated as its cation. The same is true for the 3-nitration of 2,4- ... 

Recently kinetic data have become available for the nitration in sulphuric acid of some of these hydroxy compounds (table 10.3). For 4-hydroxyquinoline and 4-methoxyquinoline the results verify the early conclusions regarding the nature of the substrate being nitrated in sulphuric acid. Plots of log Q against — (Lf + logioflHao) fo " these compounds and for i-methyl-4-quinolone have slopes of i-o, i-o and 0-97 at 25 C respectively, in accord with nitration via the majority species ( 8.2) which is in each case the corresponding cation of the type (iv). At a given acidity the similarity of the observed second-order rate constants for the nitrations of the quinolones and 4-methoxy-quinoline at 25 °C supports the view that similarly constructed cations are involved. Application of the encounter criterion eliminates the possibilities of a... 

Most of the qualitative relationships between color and structure of methine dyes based on the resonance theory were established independently during the 1940 s by Brooker and coworkers (16, 72-74) and by Kiprianov (75-78), and specific application to thiazolo dyes appeared later with the studies of Knott (79) and Rout (80-84). In this approach, the absorptions of dyes belonging to amidinium ionic system are conveyed by a group of contributing structures resulting from the different ways of localization of the 2n rr electrons on the 2n l atoms of the chromophoric cationic chain, rather than by a single formula ... 

Table 8 1 illustrates an application of each of these to a functional group transfer matron The anionic portion of the salt substitutes for the halogen of an alkyl halide The metal cation portion becomes a lithium sodium or potassium halide... 

Dowex 50W-X8 1.7 0.80 Strongly acidic cation exchanger with S-DVB matrix for separation of amino acids, metal cations, and cations. Molecular weight exclusion is <1000. 100-200 mesh is standard for analytical applications. 

Examples of the application of ion-exchange chromatography to the analysis of (a) inorganic anions, (b) inorganic cations, (c) antifreeze, and (d) vitamins. (Chromatograms courtesy of Alltech Associates, Inc. Deerfield, IL). 

Standard polyester fibers contain no reactive dye sites. PET fibers are typically dyed by diffusiag dispersed dyestuffs iato the amorphous regions ia the fibers. Copolyesters from a variety of copolymeri2able glycol or diacid comonomers open the fiber stmcture to achieve deep dyeabiHty (7,28—30). This approach is useful when the attendant effects on the copolyester thermal or physical properties are not of concern (31,32). The addition of anionic sites to polyester usiag sodium dimethyl 5-sulfoisophthalate [3965-55-7] has been practiced to make fibers receptive to cationic dyes (33). Yams and fabrics made from mixtures of disperse and cationicaHy dyeable PET show a visual range from subde heather tones to striking contrasts (see Dyes, application and evaluation). 

Application of Wet-Strength Resins. Wet-strength resins seldom are appHed to the surface of paper for enhancing wet strength because the commercially available, cationic wet-strength resins are retained so effectively internally. However, wet-strength resins are appHed frequendy to the surface of towels and tissues as creping aids. 

Ring closures based upon electrophilic processes are uncommon. The cationic cyclization in Scheme 29a proceeds via transformation of the commencing oxime into a nitrilium ion (81CC568). Schemes 29b (82CB706) and 29c (82CB714) exemplify the application of intramolecular acylation. 

Application of the above principles to the synthesis of 1,3-diselenolylium ions has been successful. iVjA -Dialkyldiselenocarbamates as their oxo esters (30) undergo acid-catalyzed cyclization and dehydration to give the cation (31) in nearly 90% yield (75JOC746, 77CC505, 80CC866, 80CC866). 

There is very little published information on the UV spectra of 1,2-benzisothiazoles, though more data are available on the 2,1-isomers. The spectra are complex with as many as six maxima above 200 nm. Representative wavelengths of maxima are collected in Table 12. In all cases the most intense bands (e > 15 000) are those at short wavelengths, but all the bands indicated in the table have molar absorptivities greater than 4000, except those of 3-amino-2,l-benzisothiazole. Saccharin absorbs weakly at 350 nm and 277 nm, with intense bands below 230 nm (ethanol solvent) (82UP41700>. It exists as the anion except in acid solutions. The UV spectra of cations formed from 3-amino-2,l-benzisothiazole are discussed in (69CB1961>. Further applications of UV spectroscopy in studying tautomeric... 

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