Salt additive

A white gelatinous precipitate of aluminium hydroxide is obtained when an alkali is added to an aqueous solution of an aluminium salt. Addition of an excess of caustic alkali causes the precipitate to redissolve, the whole process being reversed by the addition of a strong acid the actual substance present at any time depending on... 

The pale blue tris(2,2 -bipyridine)iron(3+) ion [18661-69-3] [Fe(bipy)2], can be obtained by oxidation of [Fe(bipy)2]. It cannot be prepared directiy from iron(III) salts. Addition of 2,2 -bipyridine to aqueous iron(III) chloride solutions precipitates the doubly hydroxy-bridged species [(bipy)2Fe(. t-OH)2Fe(bipy)2]Cl4 [74930-87-3]. [Fe(bipy)2] has an absorption maximum at 610 nm, an absorptivity of 330 (Mem), and a formation constant of 10. In mildly acidic to alkaline aqueous solutions the ion is reduced to the iron(II) complex. [Fe(bipy)2] is frequentiy used in studies of electron-transfer mechanisms. The triperchlorate salt [15388-50-8] is isolated most commonly. 

As with TxA2, the reactivity of PGI2 — 3 min at pH 7.6 and 37°C) made isolation of the natural substance difficult, and a pure chemical sample was obtained only through chemical synthesis. PGI2 is stable under more alkaline conditions and can be isolated and stored as a salt. Additional information on the chemistry and stabiUty of TXA2 and PGI2 has been summarized (58). 

It has often been necessary to isolate oxazine dyes as insoluble zinc salts. Addition of urea [57-13-6] CH4N2O, or thiourea [62-56-6] CH4N2S, to the reaction mixture is reported to give good yields without using zinc (12), eg, the salt (25) [33203-82-6] is formed. 

Class B direct dyes have poor leveling power and exhaustion must be brought about by controlled salt addition. If these dyes are not taken up uniformly in the initial stages it is extremely difficult to correct the urdevelness. They are dyes that have medium—high affinity and poor diffusion. In their apphcation the cellulose is entered into a dyebath containing ordy dye. The salt is added gradually and portionwise as the temperature is increased and possibly the final additions made after the dyebath has come to the bod. 

Process 2-4 is main. With an increasing concentration of alkali the rate of polymerization increases and the molecular weight decreases. The nature of hydrolyzing agent and salt additions influence the acrylamide polymerization process. Various methods of the acrylamide polymerization in the presence of alkaline agents have been reviewed [12,16,17]. 

The increase of the liquid range of binary mixtures based on a polar (e.g., EC) and a nonpolar component (e.g., DMC) by salt addition reflects the association of the electrolyte. Large freezing-point depres-... 

Catalytic activity is a result of physical contact the reaction ceases when particles no longer present a salt-additive interface. 

Salt addition to the subphase has a strong influence on monolayer formation, too. The effect of salt was studied by spreading particles la on an aqueous KCl solution of different salt concentration, with the pH of the subphase always being 5. If no salt is present at pH 5, the particles simply disappear into the subphase, as discussed earlier. However, the presence of salt causes the metal ions to penetrate the particle shell and shield the ionic groups electrostatically. Consequently, the particles become less hydrophilic and monolayer formation is improved, as indicated by the larger value of Aq. As shown in Figure 6a, a KCl concentration of 10 moles is sufficient to cause formation of a stable particle layer even at pH 5. 

Addition of such a-lithiosulfinyl carbanions to aldehydes could proceed with asymmetric induction at the newly formed carbinol functionality. One study of this process, including variation of solvent, reaction temperature, base used for deprotonation, structure of aldehyde, and various metal salts additives (e.g., MgBrj, AlMej, ZnClj, Cul), has shown only about 20-25% asymmetric induction (equation 22) . Another study, however, has been much more successful Solladie and Moine obtain the highly diastereocontrolled aldol-type condensation as shown in equation 23, in which dias-tereomer 24 is the only observed product, isolated in 75% yield This intermediate is then transformed stereospecifically via a sulfoxide-assisted intramolecular 8, 2 process into formylchromene 25, which is a valuable chiron precursor to enantiomerically pure a-Tocopherol (Vitamin E, 26). 

In order to improve the selectivity toward the formation of 1,3-PDO, we studied the influence of metal salt additives. While the addition of calcium or copper salts exhibited a moderate influence, the presence of iron salts played a significant role on the rate and selectivity of the reaction (Figure 35.1). The metal additives reduced noticeably the activity of the rhodium catalysts suggesting that they acted as a surface poison, but they modified the selectivity of the glycerol hydrogenolysis, probably through selective diol chelation. 

Figure 35.2 Influence of lanthanide salts addition on the hydrogenolysis of glycerol.

Chen, L.A., Carbonell, R.G., and Serad, G.A., Recovery of proteins and other biological compounds using fibrous materials I adsorption by salt addition, /. Chem. Technol. Biotechnol., 74, 733, 1999. 

Figure 7 Effect of salt additive on selectivity. Buffer 50 mM DAP, the specified salt, and titrated to pH 7 with phosphoric acid 200 V/cm salt concentrations (A, B, E) 40 mM, (C and D) 80 mM. For other information, see Figure 6. (From Bullock, J. A. and Yuan, L.-C., /. Microcol. Sep., 3, 241, 1991. With permission.)...

The corresponding liquid-phase chemistry can be used to promote ion formation by appropriate choice of solvent and pH, salt addition to form M.Na+ or M.NH4+, and postcolumn addition of reagents. The primary applications of ESI-MS are in the biopolymer field. The phenomenon of routine multiple charging is exclusive to electrospray, which makes it a very valuable technique in the fine chemical and biochemical field, because mass spectrometers can analyse high-molecular-mass samples without any need to extend their mass range, and without any loss of sensitivity. However, with ESI, molecules are not always produced with a distribution of charge states [137], Nevertheless, this phenomenon somehow complicates the determination of the true mass of the unknown. With conventional low-resolution mass spectrometers, the true mass of the macromolecule is determined by an indirect and iterative computational method. 

The following are further examples of amides prepared from carboxylic acids/CDI and primary amines activated by magnesium salts (additional examples are reported in ref. [90]) ... 

Of interest here is the question relating to the value for the slope coefficient, k, from equation (1), when surfactant structures incorporating both ionic (say sulphonate) and nonionic moieties are included together. The Ghanges in electric double layer effects imparted from salt addition might dominate the packing constraints and therefore the phase inversion process, or perhaps oxyethylene dehydration effects from the presence of toluene could also play a role. 

Gaudette and Coatney [115] reported that primaquine phosphate was unstable when subjected to dry heat of 100 °C in the presence of sodium chloride for 24 h, when boiled in water for 24 h and when heated for 24 h at 100 or 200 °C in melted hydrogenated vegetable oil. These findings exclude the use of primaquine phosphate as a salt additive in cooking. Primaquine phosphate was isolated from the test preparations at alkaline pH by extraction into ethylene chloride, after which primaquine phosphate was returned to an aqueous phase by shaking with 0.1 N sulfuric acid the concentration of primaquine phosphate was then determined spectrophotometrically. The ultraviolet absorption curve of primaquine phosphate has maxima at 224, 266, 282, and 300 nm, and minima at 216, 250, 276, and 310 nm. A solution containing 10 yl/mL has an optical density of 0.375 at 282 nm optical densities were proportional to concentrations. 

Sayama, K. and Arakawa, H., Effect of carbonate salt addition on the photocatalytic decomposition of liquid water over PtTiOz catalyst, /. Chem. Soc., Faraday Trans., 93,1647,1997. 

The ionic cycle is important under reaction conditions where iodide ion can exist, e.g., higher water levels (CH3OH + HI CH3I + H20) or with salt additives. However, while higher ionic iodide levels give an iridium species capable of very rapid reaction with methyl iodide, they also serve to inhibit the formation of an acyl species. The relatively slow conversion of [CH3Ir(CO)2I3] to an acyl species is almost certainly not... 

Surface disinfectants Compounds containing phenolics, chlorhexidine (not effective against bacteria spores), quaternary ammonium salts (additional activity if bis-n-tributyltin oxide present), hypochlorites such as household bleach, alcohols such as 70-95% ethanol and isopropyl (not effective against bacteria spores), potassium peroxymonosulfate, hydrogen peroxide, iodine/iodophores, and triclosan. 

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