Methanol-water alkali halides

EXAFS studies on tris-maltolatoiron(III) in the solid state and in solution, and on [Fe(Ll)3] hydrate, pave the way for detailed investigation of the hydration of complexes of this type in aqueous media.Solubilities and transfer chemical potentials have been determined for tris-maltolatoiron(III) in methanol-water, and for tris-etiwlmaltolatoiron(III) in alcohol-water mixtures and in isobutanol, 1-hexanol, and 1-octanol. Solubility maxima in mixed solvents, indicating synergic solvation, is relevant to trans-membrane transport of complexes of this type. Solubilities of tris-ethylmaltolatoiron(III) and of [Fe(Ll)3] have been determined in aqueous salt solutions (alkali halides NH4 and NR4 bromides). ... 

Viscosity of Dilute Solutions of Alkali Halides in Methanol-Water Mixtures... 

Equation (5a) applies to all the polar liquids which we have investigated, from rather viscous substances such as glycerol, or tetra and tri-ethylene glycol, to fairly inviscid fluids such as water, formamide, benzaldehyde, benzyl alcohol, and the simplest alcohols from methanol to at least 1-octanol. It holds also at all the salt concentrations we have investigated (up to 1 molar), and for all the types of solutes tried, from alkali halides to larger (X ganic salts sudi as tetrabutyl ammonium halides. 

G. Somsen and L. Weeda, Rec. Trav. Chim., 90, 81 (1971). Enthalpies of transfer of alkali halides between different solvents. Enthalpies of solution of alkali halides in formamide, Af-methylformamide, i r,Af-di-methylformamide, AT-methylacetamide, dimethyl sulfoxide, water, methanol and ammonia are discussed. 

Washburn numbers of hydrochloric acid and of alkali-metal halides have been determined in mixtures of water with methanol ethanol ... 

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 transformation of alkyl halides into alkanenitriles with cyanide ions has frequently been carried out in protic solvents such as methanol or ethanol, sometimes with the addition of water or acetone, and often at elevated temperatures. Under these conditions reaction rates decrease in the order iodides, bromides, chlorides, as would be expected. Accordingly iodide ions have a catalytic effect and increase reaction rates. The use of anhydrous ethylene glycol or di- and poly-ethylene glycols and their corresponding ethers allows the use of higher temperatures, which means better solubility of the alkali metal cyanides. There is probably additional help from the extensive solvation of the countercations by some of these hydroxy polyethers. While for primary halides yields for nitriles range up to 90% (Table 1), they drop sharply with secondary and tertiary halides. ... 

Comparison of Water and Methanol Solutions. Comparison of (-AA(7/RT)j for ions in both water and methanol solutions can be made by using (-AA(7/R2 )ua+ and (-AA(7/R2 )(j2 - as references for the alkali metal cations and halide anions respectively. These have been plotted in Figure 5 with the lyotropic numbers for each ion. Figure 5 shows that with respect to halide ions the correlation of lyotropic number with [ (-AAG/RT)j.-(-AA( /R2 )j,j -] is both linear and identical for both solvents, whereas the corresponding correlations with respect to alkali metal cations are different. In particular, with respect to these latter ions, the change of [ (-AAG/RT) j -(-AA( / )jjg+] with lyotropic number is greater in methanol solutions than in aqueous solutions. This means that for a given membrane, the variations in solute separation for alkali metal halide salts with common anions is much less in aqueous solutions than in methanol solutions, which is consistent with experimental results. Further, in the case of methanol solutions, the solute separation increases with increase in lyotropic number for the alkali metal cation series and decreases with an increase in lyotropic number for the halide series. 

Briihl875 observed that alkali salts often do not react smoothly with alkyl halides, but that in such cases addition of a little methanol may be helpful. It is essential that the salt be finely divided lead or silver salts should be washed with water, alcohol, and ether after their preparation and then dried in a vacuum-desiccator heat should be avoided during drying. 

Alkali hydroxides are most commonly used, with or without a solvent. Suitable solvents, in order of importance, are ethanol, methanol, butanol, ethanol-water mixtures, ethylene glycols and its ethers, glycerol, and hydrocarbons. The usual reagent is saturated ethanolic potassium hydroxide ca. 4n, ca. 20) at room temperature, but always more than the theoretical amount. For dehydrohalogenation of arylalkenyl halides it often suffices to reflux the compound for some time in a suitable solvent, but preparation of purely aliphatic acetylenes sometimes requires heating in an autoclave at temperatures around 170°.180 Reaction times vary, from a few minutes to several hours. 

Reaction over Base Catalysts. - Masada et al. reported a detailed study on the reaction with methyl propionate over silica-supported various base catalysts. The reaction is conducted in the presence of methanol but in the absence of water vapor. HCHO free from water is obtained by the thermal decomposition of cyclohexanol-hemiformal which was previously prepared from formalin and cyclohexanol. The performances of catalysts are summarized in Table 8. The KOH catalysts are more active than the CsOH catalysts, although the selectivity to methyl methacrylate is lower. Incorporation of halides of alkali metal into the KOH catalyst improves the yield of methyl methacrylate, though the halides by themselves are inactive for the reaction. The best results are obtained with a KOH (1.5 percent) + Csl (0.5 percent) on silica catalyst. The single-pass yield of methyl methacrylate reaches about 59 mol% based on the charged HCHO with a methyl propionate/HCHO/ methanol molar ratio of 10/1/10. It is also found that the selectivity of methyl propionate to methyl methacrylate is very high, nearly 100 mol%. The best support is found to be silica gel. No catalytic activity is observed with the alumina-supported catalysts. 

Nearly all the ions show some temperature dependence in aqueous solution, but at least for the tetraalkylammonium ions, very little in methanol solutions (Figure 4). Instead of increasing, B decreases with increasing size for the alkali metal and halide ions. The negative values of B indicate that most of these ions actually decrease the viscosity upon their addition to water. The B coefficients for the tetraalkylammonium ions increase with increasing size but for the larger ions, B is much larger in aqueous than in methanol solutions and extremely temperature dependent in aqueous solution. 

Moss and Wolfenden and Slansky have reported heats for several alkali metal halides and HCl in water-methanol mixtures ranging from 0 to 100% alcohol. In every case there is a maximum in the heat of solution at a solvent composition of approximately 20 mol per cent methanol. The data for the pure methanol solutions from these investigations and those of earlier workers have been compiled as heats of formation by Rossini and co-workers. Only in a few cases are the data given at infinite dilution. 

Mishchenko and co-workers ° and Krestov and Klopov have measured heats of solution for several alkali and alkaline earth metal halides and nitrates in water-methanol mixtures. The data, which are given only in graphical form, indicate the same functional dependence upon alcohol concentrations as those reported by Slansky, and Moss and Wolfenden. ... 

Partial molal entropy data in ethanol are nearly as sparse as the heat capacity data. The only comprehensive entropy data in this solvent are those of Jakuszewski and Taniewska-Osinska, who report 5 for HCl and several alkali metal halides in ethanol. Ionic entropies have been calculated for the alkali metals from free energies and enthalpies of solvation, but since extra-thermodynamic assumptions were necessary, the meaning of the values is questionable. Ionic entropies in ethanol are somewhat more negative than in methanol and considerably more negative than in water. 

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