Alcohol-water mixtures acidity

To make sols containing up to 50% -SiO by dissolving silicon. Bobb (114) claims the use of an aqueous solution of an inorganic base (NaOH, KOH) to catalyze the dissolution at 50-100 C and stabilize the resulting sol. It is remarkable that sols made at 90-95 C were said to be very viscous but when made at 98-lOO C were of normal low viscosity. Particle sizes were between 15 and 45 nm. Also the sols were unusual in that they did not form hard gels when acidified, but only soft coacervates. These differences are unexplained. An alcosol is obtained when silicon is used an an anode and dissolved by electrolysis in an alcohol-water mixture. Acid or a metal salt is added to provide conductivity according to Tripp (91) or Chilton (115). 

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. 

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. 

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 ... 

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... 

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-... 

Later, Torii et al. found that the tin-aluminum-mediated allylation can be carried out with the less expensive allyl chloride, instead of allyl bromide, when a mixture of alcohol-water-acetic acid was used as the solvent.77 When combined with stoichiometric amounts of aluminum powder, both stoichiometric and catalytic amounts of tin are effective. As reported by Wu et al., higher temperatures can be used instead of aluminum powder.78 Under such a reaction condition, allyl quinones were obtained from 1,4-quinones, followed by oxidation with ferric chloride. Allylation reactions in water/organic solvent mixtures were also carried out electrochemically, with the advantage that the allyltin reagent could be recycled.79... 

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... 

Cohn, E.J., McMeekin, T.L., Edsall, J.T., and Weare, J.H. Studies in the physical chemistry of amino acids, peptides and related substances. II. The solubility of a-amino acids in water and in alcohol-water mixtures, J. Am. Chem. Soc., 44(3) 451-460, 1922. 

It will be observed that the F, N curves for such binary mixtures follow the same course—a rapid followed by a more gentle rise of F as iV increases to a well defined maximum followed by a drop and an asymptotic fall in the F value. In the case of alcohol water mixtures F ax. is obtained at about 0 3A. To find an adequate explanation for the complete F, N curve is by no means an easy matter. It is clear that the first portion of the curve may be taken to represent an increasing surface concentration of alcohol and this proceeds to a limiting value—an observation first made by Milner (Phil. Mag. xill. 96, 1907), who showed that for relatively strong solutions of acetic acid the surface tension of the solutions could be expressed as a function of the concentration of the acetic acid in the following form ... 

Reports have appeared claiming that triperoxo vanadates behave as nucleophilic oxidants. In particular, triperoxo vanadium complexes, A[V(02)3]3H20 (A=Na or K), are proposed as efficient oxidants of a,-unsaturated ketones to the corresponding epoxide, benzonitrile to benzamide and benzil to benzoic acid, reactions which are usually carried out with alkaline hydrogen peroxide. Subsequent studies concerning the oxidation of cyclobutanone to 4-hydroxybutanoic acid, carried out with the above-cited triperoxo vanadium compound, in alcohol/water mixtures, clearly indicated that such a complex does not act as nucleophilic oxidant, but only as a source of HOO anion. 

Hydrolysis of tetraalkoxysilanes in pure water is usually incomplete, but it is more effectively carried out in an alcohol-water mixture and can be catalyzed by H+ or weak bases such as ammonia. Polymerization occurs in the range pH 2-7 under neutral conditions, the rate of polymerization is limited by the slowness of hydrolysis, whereas in acidic media hydrolysis is complete before polymerization begins. The nanostructure of the gel (density of particles, fractal dimensions of particle clusters, and degree of cross-linking of particles to form a network) is controlled by these conditions. 

Many papers concerning salt effect on vapor-liquid equilibrium have been published. The systems formed by alcohol-water mixtures saturated with various salts have been the most widely studied, with those based on the ethyl alcohol-water binary being of special interest (1-6,8,10,11). However, other alcohol mixtures have also been studied methanol (10,16,17,20,21,22), 1-propanol (10,12,23,24), 2-propanol (12,23,25,26), butanol (27), phenol (28), and ethylene glycol (29,30). Other binary solvents studied have included acetic acid-water (22), propionic acid-water (31), nitric acid-water (32), acetone-methanol (33), ethanol-benzene (27), pyridine-water (25), and dioxane-water (26). 

Prepared similarly to the nitrate. Six grains of finely powdered aquopentammine bromide (No. 112 b) are nsed with the same amounts of oxalic acid and the alcohol-water mixture, Heating on the steam bath requires 10 minutes brick-red powder. 

Commonly used extraction solvents are ethyl acetate, diethyl ether, methanol, and aqueous methanol, but the majority of the free phenolic compounds can be extracted with alcohols (methanol or ethanol) or alcohol-water mixtures (1). Due to the differences in polarity between components (40), neither diethyl ether nor ethyl acetate are able to extract completely all the phenolic compounds in a liquid-liquid extraction. Thus, successive extraction with diethyl ether and then ethyl acetate has been used for phenolics in fruit juices (41). When using alcohol-water mixtures (40), repeated extraction or reflux for 1 h are necessary to extract free phenolic acids as well as their glycosides. 

Selectivities for alcohol-water mixtures depend strongly on the pH of the solution. If the pH is sufficiently high that the alcohol and water are partially deprotonated, then alkoxide and hydroxide will be effective nucleophiles, and their concentrations will depend on the p Kz values of the alcohol and water. For relatively acidic alcohols, calculation of S using Equation 2.9 could then give S values over 1000, e.g. nucleophilic aromatic substitutions, including the dyeing of cotton using fibre-reactive dyes [42]. 

Amino Acids and Peptides. The amino acids and peptides used were high grade commercial products, further purified by recrystallization from alcohol-water mixtures, except when they were chromato-graphically pure. Glycolamide was prepared by passing dry ammonia into cold, freshly distilled ethyl glycollate. Pure lactamide was obtained from E. H. Harris of this laboratory. 

Endothermic maxima are also observed in plots of 5m//f for carboxylic acids in t-butyl alcohol + water mixtures at x2 0-05. The importance of the hydrophobic side chain in determining the height of these maxima is confirmed by the observation that these become more intense as the size of the alkyl group increases. Indeed the function 5R 6m//e, calculated for replacement of H- by CH3-, has an endothermic maximum near x2 = 0-05 (Avedikian et al., 1973). 

More marked dependences on mole fraction are observed in the related enthalpy and entropy functions, 8mAH and 5mAS , e.g. acetic and chloracetic acids in ethyl alcohol + water mixtures (Millero et al., 1969). Extrema in these quantities are observed for... 

A. Add 25 mL of 1 2 hydrochloric acid to about 1.5 g of sample, and dilute to 50 mL with water. Heat to effect complete solution then cool filter on a fine-porosity, sintered-glass crucible wash the precipitate with 2 100 hydrochloric acid, saving the filtrate for Identification Test B and dry the precipitate at 105°. Add 3 mL of water and 7 mL of 1 A sodium hydroxide to 400 mg of the dried precipitate, and stir until solution is complete. Add, dropwise, 2.7 A hydrochloric acid until the solution is just acid to litmus add 1 g of p-nitrobenzyl bromide and 10 mL of alcohol and reflux the mixture for 2 h. Cool, filter, and wash the precipitate with two small portions of a 2 1 alcohol water mixture, followed by two small portions of water. The precipitate, recrystallized from hot alcohol and dried at 105°, melts at about 152° (see Melting Range or Temperature, Appendix IIB). 

The calculated values are from the mixture rule c pi+p =ciPi+C2P2i where Pu Pi are the weights of the components with specific heats ci and C . The mixture rule is closely obeyed by mixtures of chloroform and carbon tetrachloride, benzene and carbon tetrachloride, and chlorobenzene and bromo-benzene, but mixtures of chloroform and acetone have smaller specific heats than the calculated. Jamin and Amaury found with alcohol-water mixtures fliat the increase in specific heat is proportional to the density increase due to. contraction, and the same result was found for water-acetic acid mixtures by von Reiss.3... 

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