Sodium water structure former

Because the only variable changed in this dissolution study was the type of alkali metal hydroxide, differences in dissolution rate must be attributed to differences in adsorption behavior of the alkali metal cations. The affinity for alkali metal cations to adsorb on silica is reported (8) to increase in a continuous way from Cs+ to Li+, so the discontinuous behavior of dissolution rate cannot simply be related to the adsorption behavior of the alkali metal cations. We ascribe the differences in dissolution rate to a promoting effect of the cations in the transport of hydroxyl anions toward the surface of the silica gel. Because differences in hydration properties of the cations contribute to differences in water bonding to the alkali metal cations, differences in local transport phenomena and water structure can be expected, especially when the silica surface is largely covered by cations. Lithium and sodium cations are known as water structure formers and thus have a large tendency to construct a coherent network of water molecules in which water molecules closest to the central cation are very strongly bonded slow exchange (compared to normal water diffusion) will... 

Conversely, the addition of some other ions can promote solubility by the indifferent electrolyte effect. The use of hydrophilic molecules such as the hydroxyacids (e.g. citrate, tartaric) or aromatic carboxylic acids (e.g. benzoic) can create cavities in the water structure thereby promoting solubilization. Many salt formers increase drug solubility by this type of mechaiusm. Citrate buffers and sodium benzoate, the latter often used in formulations as an antimicrobial preservative, are known to enhance the solubility of a number of drugs. 

Since the discovery of LPS (Shear, 1941), various methods for the extraction of LPS have been developed. These include extraction with trichloroacetic acid (Ribi et al., 1961), with ether (Galanos et al., 1969), with water (Robert et al., 1967), with pyridine (Goebel et al., 1945), with phenol (Westphal and Jann, 1965), with butanol (Morrison and Leive, 1975), and with sodium dodecyl sulfate (SDS) (Darveau and Hancock, 1983). A few of these methods can chemically alter the structure of LPS (Nowotny et al., 1966 Tsang et al., 1974 Wober and Alaupovic, 1971). Among these methods, the most used are the phenol-water extraction (Westphal and Jann, 1965) and the ether extraction (Galanos et al., 1969). The former is most efficient for the extraction of S-LPS, while the latter for R-LPS. A method which could efficiently extract both S-LPS and R-LPS has also been developed (Darveau and Hancock, 1983). 

While the isolation of des-base-A as one of the products of the Hofmann reaction has added further support for the structure assigned to methyl-(chano)-dihydroneostrychnidine, yet it is the isomeric des-base, anhydro-methylstrychnidinium-D hydroxide (des-base-D, m.p. 196-197°) that has provided a whole series of new compounds by a novel reaction. Introduction of two hydrogen atoms into des-base-D by catalytic reduction (palla-A solution of 9.0 g. of des-basc-D in 130 cc. of 10% hydrochloric acid is shaken with hydrogen at 17-19° in the presence of palladium-charcoal catalyst. The uptake of hydrogen ceases when 355 cc. of hydrogen (theory 600 cc.) is absorbed. Further addition fails even at 90°. The hot solution is filtered, made ammoniacal, and concentrated under vacuum to one-third its volume. The concentrate, when treated with a solution of 10 g. of sodium iodide in 10 cc. of water, yields a colorless precipitate which is a mixture of methyldihydrostrychnidinium-D iodide and methyldihydrostrychnidinium-A iodide. Repeated fractional crystallization from water yields 8.7 g. of the former (m.p. 325-327°) and 3.2 g. of the latter (m.p. 345-350°). 

Kurumada et al. [86] investigated the structure and percolation of water/oil microemulsions employing sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl) phosphate (SDEHP). The sulfosuccinate-derived microemulsions have produced spherical aggregates, whereas those derived from the phosphate are composed of cylindrical aggregates. But the preparations have shown percolation in conductance the conductance increase with the phosphate system is 10-100 times more than that with the succinate system. Moreover, for the former, (]), 0.06. and for the latter cj), 0.4-0.5. In the region of c >, > 0.2, the electrical conductivity of the phosphate system has been found to be 1000-fold... 

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