Mixtures alcohols + water

We have considered the surface tension behavior of several types of systems, and now it is desirable to discuss in slightly more detail the very important case of aqueous mixtures. If the surface tensions of the separate pure liquids differ appreciably, as in the case of alcohol-water mixtures, then the addition of small amounts of the second component generally results in a marked decrease in surface tension from that of the pure water. The case of ethanol and water is shown in Fig. III-9c. As seen in Section III-5, this effect may be accounted for in terms of selective adsorption of the alcohol at the interface. Dilute aqueous solutions of organic substances can be treated with a semiempirical equation attributed to von Szyszkowski [89,90]... 

Estimate the interfacial tension gradient formed in alcohol-water mixtures as a function of alcohol content. Determine the minimum alcohol content necessary to form wine tears on a vertical glass wall [174] (experimental veriflcation is possible). 

Add 40 ml. of ethyl alcohol to 21 -5 g. of 70 per cent, ethylenediamine solution (0 -25 mol) dissolve 36 -5 g. of adipic acid (0 -25 mol) in 50 ml. of a 6 1 mixture of ethyl alcohol and water. Mix the two solutions, stir and cool. Filter off the resulting salt and recrystalliae it from 60 ml. of a 6 1 ethyl alcohol - water mixture, and dry the salt in the air. Heat the salt in an atmosphere of oxygen-free nitrogen or of carbon dioxide in an oil bath until it melts (ca. 160°) the product will sohdify after a short time. Reduce the pressure to 15 mm. of mercury or less and raise the temperature of the oil bath until the product remelts (about 290°) and continue the heating for 4r-5 hours. Upon coohng, a nylon type polymer is obtained. 

Breslow studied the dimerisation of cyclopentadiene and the reaction between substituted maleimides and 9-(hydroxymethyl)anthracene in alcohol-water mixtures. He successfully correlated the rate constant with the solubility of the starting materials for each Diels-Alder reaction. From these relations he estimated the change in solvent accessible surface between initial state and activated complex " . Again, Breslow completely neglects hydrogen bonding interactions, but since he only studied alcohol-water mixtures, the enforced hydrophobic interactions will dominate the behaviour. Recently, also Diels-Alder reactions in dilute salt solutions in aqueous ethanol have been studied and minor rate increases have been observed Lubineau has demonstrated that addition of sugars can induce an extra acceleration of the aqueous Diels-Alder reaction . Also the effect of surfactants on Diels-Alder reactions has been studied. This topic will be extensively reviewed in Chapter 4. 

Freezing point of ethyl alcohol-water mixtures ... 

Meclizine Hydrochloride. Pipera2ine Antivert, and Bonine are trade names for mech2ine dihydrochloride monohydrate [31884-77-2] (20). It is a white or slightly yellowish crystalline powder with a slight odor, no taste, and a melting point of 217—224°C. The hydrochloride is practically insoluble in water and ether. It is freely soluble in chloroform, pyridine, methylacetamide, and mild acid alcohol—water mixtures, and is slightly soluble in dilute acids or alcohol. See Reference 16 for synthesis. 

Concentration Effects. The reactivity of ethyl alcohol—water mixtures has been correlated with three distinct alcohol concentration ranges (35,36). For example, the chromium trioxide oxidation of ethyl alcohol (37), the catalytic decomposition of hydrogen peroxide (38), and the sensitivities of coUoidal particles to coagulation (39) are characteristic for ethyl alcohol concentrations of 25—30%, 40—60%, and above 60% alcohol, respectively. The effect of various catalysts also differs for different alcohol concentrations (35). 

There are three general methods of interest for the preparation of vinyl chloride, one for laboratory synthesis and the other two for commercial production. Vinyl chloride (a gas boiling at -14°C) is most conveniently prepared in the laboratory by the addition of ethylene dichloride (1,2-dichloroethane) in drops on to a warm 10% solution of sodium hydroxide or potassium hydroxide in a 1 1 ethyl alcohol-water mixture Figure 12.1). At one time this method was of commercial interest. It does, however, suffer from the disadvantage that half the chlorine of the ethylene dichloride is consumed in the manufacture of common salt. 

Because of its high polarity, polyfvinyl alcohol) is very resistant to hydrocarbons such as petrol. Although the polymer will dissolve in lower alcohol-water mixtures, it does not dissolve in pure alcohols. As it is crystalline as well as... 

Table 4.11 lists the Y values for some alcohol-water mixtures and for some other solvents. The Y value reflects primarily the ionization power of the solvent. It is largest for polar... 

Sn2 reactions with anionic nucleophiles fall into this class, and observations are generally in accord with the qualitative prediction. Unusual effects may be seen in solvents of low dielectric constant where ion pairing is extensive, and we have already commented on the enhanced nucleophilic reactivity of anionic nucleophiles in dipolar aprotic solvents owing to their relative desolvation in these solvents. Another important class of ion-molecule reaction is the hydroxide-catalyzed hydrolysis of neutral esters and amides. Because these reactions are carried out in hydroxy lie solvents, the general medium effect is confounded with the acid-base equilibria of the mixed solvent lyate species. (This same problem occurs with Sn2 reactions in hydroxylic solvents.) This equilibrium is established in alcohol-water mixtures ... 

The solvent was evaporated from the combined benzene extracts to give 33.4 g of a clear light brown resin. Crystallization from an alcohol-water mixture gave 19.5 g of 1-methyl-4-(5-hydroxy-5-dibenzo[a,e] cycloheptatrienyO-piperidine, MP 156° to 157°C. Two recrystallizations from alcohol-water mixtures followed by two recrystallizations from benzene-hexane mixtures gave analytically pure product, MP 166.7° to 167.7°C. 

Some ligand-exchange CSPs have been used at preparative level [31, 32]. In this case it must be taken into account that an extraction process, to remove the copper salts added to the mobile phase, must be performed following the chromatographic process [33]. Teicoplanin, in contrast, resolves all ordinary a and (3-amino acids with mobile phases consisting of alcohol/water mixtures. No buffer is needed in the... 

Some typical dispersion polymerization recipes and the electron micrograph of the uniform polymeric particles with Recipe I are given in Table 5 and Fig. 10, respectively. As seen in Table 5, the alcohols or alcohol-water mixtures are usually utilized as the dispersion media for the dispersion polymerization of apolar monomers. In order to achieve the monodispersity in the final product, a costabilizer can be used together with a primary steric stabilizer, which is usually in the polymeric form as in... 

We have studied the effect of monomer concentration in the dispersion polymerization of styrene carried out in alcohol-water mixtures as the dispersion media. We used AIBN and poly(acrylic acid) as the initiator and the stabilizer, respectively, and we tried isopropanol, 1-butanol, and 2-butanol as the alcohols [89]. The largest average particle size values were obtained with the highest monomer-dispersion medium volumetric ratios in 1-butanol-water medium having the alcohol-water volumetric ratio of 90 10. The SEM micrographs of these particles are given in Fig. 15. As seen here, a certain size distribution by the formation of small particles, possibly with a secondary nucleation, was observed in the poly-... 

Figure 7-52B. Flashpoints of ethyl alcohol-water mixtures as a function of liquid phase concentration at one atmosphere total pressure. By permission, Hercules, Inc.

The production of heers and ciders requires the fermentation of sugary fluids hy the action of yeasts, and the cooling, filtration, clarification and storage of the resulting alcohol-water mixture. 

Fig. 9-1. Iodine dissolving in an alcohol-water mixture. Equilibrium is recognized by constant color of the solution.

Figure 9-1C shows a system at equilibrium. Solid iodine has dissolved in an alcohol-water mixture until the solution is saturated. Then no more solid dissolves and the color of the solution remains constant. 

Consideration of the dissolving of iodine in an alcohol-water mixture on the molecular level reveals the dynamic nature of the equilibrium state. The same type of argument is applicable to vapor pressure. 

Reverse-phase Squalane Zipax-HCP Cyanoethylsilicone Water and alcohol-water mixtures acetonitrile and acetonitrile-water mixtures... 

Bowen et al. [94] made a B-MFI membrane on a monohthic support. The pervaporation fluxes and selectivities of several alcohol/water mixtures were comparable to similar tubular-based B-MFI membranes, demonstrating the scale-up, although, for pervaporation, the quality requirements are much more forgiving. Kuhn etal. tested a multicharuiel high-silica MFI membrane for ethanol/water separation. The membrane was supphed by NGK Insulators and, also, in this case, the multicharuiel membrane measures up to its tubular counterparts [95] (Figure 10.8). 

Strong infusions are made by soaking tea leaves in alcohol/water mixtures (the catechin content is about 2% w/v). 

Gelsema, W. J. de Ligny, C. L. Remijnse, A. G. Blijleven, H. A., pH-measurements in alcohol-water mixtures, using aqueous standard buffer solutions for calibration, Reel. Trav. Chim. Pays-Bas 85, 647-660 (1966). 

Tindell, W.A., Misak, M.O., and Gras, E.H. "The Use of Alcohol Water Mixtures in Fracture Stimulation of Gas Wells," 1974 Proc. Annu. Southwest. Pet. Short Course, Lubbock, 61 65. 

Moreover, in this example, the solvent systems used are also incompatible. The Grubbs catalyst is used in a relatively dry, nonpolar solvent to dissolve the substrates, whereas the AD-mix is placed in various alcohol-water mixtures. 

Dissolve a dendrimer in 50 percent methanol/water at a concentration of at least lOmg/ml. Singh (1998) used about 165mg of a G-5 PAMAM dendrimer dissolved in 1 ml of the alcohol/water mixture. Use a fume hood for all operations. 

Cereal proteins when classified by the Osborne sequential extraction method yield four different classes albumins, which are water soluble, globulins, which are soluble in salt solutions, prolamins, which are soluble in alcohol-water mixtures, and glutelins, which are soluble in dilute acid or alkali. Chen and Bushuk added a fifth fraction by dividing the glutelin into two fractions, one soluble in dilute (0.05 m) acetic acid and the other insoluble in this reagent.5... 

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