Anion water-methanol

All of these compounds 151a (Figure 16) have been made from the lithium salt of anionic tridentate phosphino-borate 152 or more conveniently from the thallium(l) derivative 153, available from 152 and T1PF6 in water-methanol media (Scheme 60) <1999CC2379, 1999JA9871, 2001CC2152, 2003IC5074>. 

The CE behaviour of inorganic anions in water-methanol mixtures has also been extensively studied. The specific conductivity a of electrolytes was converted into equivalent conductivity by... 

A similar conclusion arises from the capacitance data for the mercury electrode at far negative potentials (q 0), where anions are desorbed. In this potential range, the double-layer capacitance in various electrolytes is generally equal to ca. 0.17 F Assuming that the molecular diameter of water is 0.31 nm, the electric permittivity can be calculated as j = Cd/e0 = 5.95. The data on thiourea adsorption on different metals and in different solvents have been used to find the apparent electric permittivity of the inner layer. According to the concept proposed by Parsons, thiourea can be treated as a probe dipole. It has been cdculated for the Hg electrode that at (7 / = O.fij is equal to 11.4, 5.8, 5.1, and 10.6 in water, methanol, ethanol, and acetone, respectively. 

Water-soluble l,3-bis(di(hydroxyalkyl)phosphino)propane derivatives were thoroughly studied as components of Pd-catalysts for CO/ethene (or other a-olefins) copolymerization and for the terpolymerization of CO and ethene with various a-olefins in aqueous solution (Scheme 7.17) [59], The ligands with long hydroxyalkyl chains consistently gave catalysts with higher activity than sulfonated DPPP and this was even more expressed in copolymerization of CO with a-olefins other than ethene (e.g. propene or 1-hexene). Addition of anionic surfactants, such as dodecyl sulfate (potassium salt) resulted in about doubling the productivity of the CO/ethene copolymerization in a water/methanol (30/2) solvent (1.7 kg vs. 0.9 kg copolymer (g Pd)" h" under conditions of [59]) probably due to the concentration of the cationic Pd-catalyst at the interphase region or around the micelles which solubilize the reactants and products. Unfortunately under such conditions stable emulsions are formed which prevent the re-use... 

The emission spectra of 10-CPT in water-methanol mixtures exhibits dual fluorescence (Fig. 1 left). The appearance of the low energy emission band at 570 nm for 10-CPT in a neat methanol solution indicates an efficient PTTS process. The large fluorescence quantum yield and similarity of the emission at neutral and basic solutions is evidence of the excited anion (RO ) formation, in contrast to 6HQ, for which double PTTS leads to the tautomer [2], With the increase of water content in the mixtures, we observed a substantial decrease in the fluorescence intensity of the nondissociated form of 10-CPT at 430 nm and a concomitant increase of RO " intensity at 570 nm. This is a well-known effect in hydroxyaromatic compounds [4] and is attributed to the increase of the protolytic photodissociation rate with increasing water concentration. 

Studying the ESPT of hydroxy aromatic sulfonates, Huppert and co-workers [40-44] suggested an alternative model based on the geminate proton-anion recombination, governed by diffusive motion. The analysis was carried out by using Debye-Smoluchowskii-type diffusion equations. Their ESPT studies in water-methanol mixtures showed that solvent effects in the dissociation rate coefficient are equal to the effects in the dissociation equilibrium constant [45], 4-Hydroxy-1-naphthalenesulphonate in a water-propanol mixture as the solvent system has been found to behave somewhat differently than water-methanol or water-ethanol media, with a possible role of a water dimer [46,47],... 

Solid state analysis of crystals obtained of receptor with acetate from water/methanol solutions reveal that once again the guanidiniocarbonylpyrrole cation exists in an extended conformation however in contrast to the proposed solution state model, the pyrrole NH points away from the guanidium NHs with the acetate anions bound by two separate receptor groups with solvent molecules helping to create a series of 2D arrays (figure 23c). 

The bicyclic guanidinium tetramer 43 was first reported as a possible binder for helical oligonucleotides. Initial studies with 43 and sulfate anions showed that the tetramer formed double-helical dimers around sulfate counterions [69]. Despite the initial proposal of using this receptor for membrane transport of oligonucleotides, all subsequent work on 43 has been conducted on helical peptides. For example, the binding of 43 with several synthetic peptides caused an increase in the helicity and helical stability of the peptides in 10% water/methanol [70]. The peptide containing four Asp derivatives showed the... 

Protic character. The protic character of the solvent is an important consideration because electrochemical intermediates (particularly radical anions) frequently react rapidly with protons. The classification of solvents into protic or aptotic solvents is somewhat arbitrary. A simple classification1 is that protic solvents (such as hydrogen fluoride, water, methanol, formamide, and ammonia) are strong hydrogen-bond donors, exchange protons rapidly, and in-... 

Sherrington and coworkers161 have examined the chlorination of phenol by J-butyl hypochlorite in the presence of cross-linked polystyrenes substituted by pendant polymethylene chains terminated with anionic or cationic head groups, as well as some hydrophilic acrylic polymers, in four solvents water, methanol, 1,2-dichloroethane and xylene. The polymers exerted a significant influence on the chlorination, particularly in polar solvents. However, no changes in the regioselectivity of the chlorination, in comparison to homogeneous systems, was observed. 

The shapes and intensities of spectral bands were used in complexation studies of lanthanide nitrates in organic solvents. The degree of complexation of nitrate was in the order water > methanol > acetonitrile. The tendency of the nitrate anion and the solvent molecules to compete for coordination followed the order DMF > TBP > NOJ > H2O > C2H5OH > dioxane. The 4f-4f spectral band of Nd(C104>3 in DMF, DMSO and DMSO-H2O mixtures split into two components whose relative intensities were attributed to different amounts of nona- and octacoordinated Nd(III) solvated ion. The major species are [Nd(DMF)9]3+/[Nd(DMSO)9]3+ and the minor species are [Nd(DMF)8]3+/[Nd(DMSO>9]3+. Addition of water to the equilibrium mixture resulted in a shift of the equilibrium to predominantly nonacoordinated species due to substitution of DMF/DMSO by water along with a red shift of the spectral band [224,225]. 

When in a mixture of two solvents, both ions of a binary salt are solvated preferably by the same solvent, the term applied is homoselective solvation (Fig. 2-lOa). Similarly, the preferred solvation of the cation by one, and the anion by the other solvent, is termed heteroselective solvation (Fig. 2-lOb) [119], Thus, in a solution of silver nitrate in the binary solvent mixture acetonitrile/water, a preferential solvation of Ag by acetonitrile and of NO by water was observed (heteroselective solvation) [121, 369] . In contrast, in solutions of calcium chloride in water/methanol mixtures, both Ca and Cl are solvated largely by water (homoselective solvation) [122], Zn (from ZnCl2) in... 

Solvents such as water, methanol, MeCN or DMF dissolve a variety of inorganic supporting electrolytes, while only organic supporting electrolytes are used for organic solvents. Ilie anion part of the commonly used supporting electrolyte is X" (halide anion), C104, BE , PFe", OTs or RO , whereas the cation is (alkali metal cation) or R N. ... 

The isolation of this neutral complex is facilitated by its lower solubility in the mixture of polar solvents (water-methanol) used in the synthesis. When [M (CN)6l anions (M = Cr, Fe) are used as starting materials in the reaction, the formation of a neutral species is not so straightforward, and various products are... 

The strong anion-solvating power of water, methanol, and many other hydroxylic solvents is due to hydrogen bond formation. 

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