Conductance, 31. acids water

Microstructure. Interest in PVP microstmcture and the potential for tacticity has been reviewed (39,40). PVP generated by free radicals has been shown to be atactic except when polymerization is conducted in water. In this case some syndiotacticity is observed (40). In the presence of syndiotactic templates of poly(methacryhc acid) (or poly(MAA)), VP will apparentiy polymerize with syndiotactic microstmcture, although proof is lacking (41—45). The reverse, polymerization of MAA in the presence of PVP, affords, as expected, atactic poly(MAA) (46,47). 

RAFT polymerization of two anionic acrylamido monomers sodium 2-acrylamido-2-methylpropane-sulfonate, AMPS, and sodium 3-acrylamido-3-methyl-butanoate, AMBA, (Scheme 29) was conducted in water at 70 °C using 4,4/-azobis(4-cyanopentanoic acid) as the initiator and 4-cyanopentanoic acid dithiobenzoate as the RAFT chain transfer agent [80]. The synthesis was initiated either from one monomer or the other leading to narrow molecular weight distributions in both cases (Mw/Mn < 1.2). 

Fang, J., Guo, X., Harada, S., Watari, T., Tanaka, K., Kita, H. and Okamoto, K. 2002. Novel sulfonated polyimides as polyelectrolytes for fuel cell applications. 1. Synthesis, proton conductivity, and water stability of polyimides from 4,4 -diaminophenyl ether-2,2 -disulfonic acid. Macromolecules 35 9022-9028. 

For the polyhydroxy compounds to be examined, the conductivity in water and subsequently (as a rule) in 0.5 M boric acid at 25 C. was determined. The increase in. this conductivity (called the conductivity... 

The synthesis of the right-hand fragment of ziprasidone started with a Wolff-Kishner reduction of isatin 43 to give the oxmdole 44 (Scheme 14). Friedel-Crafts acylation with chloroacetyl chloride afforded aryl ketone 45, which was reduced with triethylsilane in trifluoroacetic acid to the phenethyl chloride 46. The two fragments were joined by alkylation of 40 with 46 in the presence of Nal and Na2CO3 to give ziprasidone (4) in low yield. The yield of the coupling step was improved dramatically when the reaction was conducted in water (Scheme 15). 

The xanthenes exist in solution in several different forms depending on pH, as shown in Figure 2 and Table 1 [18]. The emission quantum yield of fluorescein depends on the acidity of the solution, the fluorescence intensity decreasing as the protonated forms of the dye come to predominate with decreasing pH. This pH sensitivity allows fluorescein derivatives to be employed as pH indicators, to measure the pH inside living cells [19-22], at water-lipid interfaces [23], and in the interior of phospholipid vesicles [24]. The sensitivity of fluorescein emission to the pH of the medium has also been used to measure lateral proton conductances at water-lipid interfaces [25-28] and proton translocation across phospholipid vesicles [29] and to determine the electrostatic potential of macromolecules [30, 31]. The pheno-... 

Irradiation of 2,6-dimethylpyran-4-one (357) in ethanol or benzene or in the solid state yields the cage-like molecule (358) from which the pyran-4-one is regenerated by hydrochloric acid (63JA1208). When the photodimerization is conducted in water but in the absence of air, a small amount of 4,5-dimethylfuran-2-aldehyde is also formed (63JA2956). Pyran-4-one is photoisomerized to pyran-2-one (359) the intermediates postulated resemble those suggested in the irradiation of pyrylium salts (Section 2.23.2.1) (79JA7521). 

Conductivity, in water activity measurement, 67-70 Confocal laser scanning microscopy to characterize lipid crystals, 575-579 description of, 575, 577 Conjugated dienes and trienes, determination of, 515-517 Conjugated linoleic acid (CLA), fatty acid analysis, 437-438, 445-446 Convection oven, gravimetric measurement of water, 7-8, 10-11... 

Reverse-phase chromatography has been used extensively for the determination of saccharin. Smyly et al. (30) and Eng et al. (39) used /rBondapak Cl 8 and 5% acetic acid for the determination of saccharin. Based on this work, an Association of Official Analytical Chemists (AOAC) collaborative study was conducted, and the method using a mobile phase buffered to pH 3 with sodium acetate and modified with 3% isopropanol was adopted. Webb and Beckman (61) used this method successfully for the separation of saccharin from aspartame, caffeine, sodium benzoate, and artificial colors and flavors. Veerabhadrarao et al. (27) added methanol to the mobile phase (methanol acetic acid water, 4 1 1, v/v) for improved separation of saccharin from caffeine, benzoic and p-hydroxybenzoic acids, vanillin, aspartame, acesulfame-K, and dulcin. Saccharin was also determined using LiChrosorb Cl8 and 4 6 v/v methanol phosphate buffer,... 

Because of the complexity of hydrated PEMs, a full atomistic modeling of proton transport is impractical. The generic problem is a disparity of time and space scales. While elementary molecular dynamics events occur on a femtosecond time scale, the time interval between consecutive transfer events is usually 3 orders of magnitude greater. The smallest pore may be a few tenth of nanometer while the largest may be a few tens of nanometers. The molecular dynamics events that protons transfer between the water filled pores may have a timescale of 100-1000 ns. This combination of time and spatial scales are far out of the domain for AIMD but in the domain of MD and KMC as shown in Fig. 2. Because of this difficulty, in the models the complexity of the systems is restricted. In fact in many models the dynamics of excess protons in liquid water is considered as an approximation for proton conduction in a hydrated Nation membrane. The conformations and energetics of proton dissociation in acid/water clusters were also evaluated as approximations for those in a Nation membrane.16,19 20 22 24 25... 

The addition of water to alkynes is also aided by the presence of mercury (II) salts. The reaction is usually conducted in water, with the presence of a strong acid, such as sulfuric acid, and a mercury salt, such as HgS04 oi HgO. In this case the mercury is spontaneously replaced by hydrogen under the reaction conditions, so a second step is not necessary. The addition occurs with a Markovnikov orientation stereochemistry is not an issue. 

A quite different chiral catalyst 136 can be used to promote the reaction of some pyrroles and indoles with benzoylhydrazones (Scheme 64) <2005JA2858>. Condensations of indoles with a variety of imines can be conducted in water with decanoic acid ( -C9H19C02H) as the catalyst <2006OL4939>. 

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