Water-methanol-ethanol mixtures

Solubility In Ethanol-Methanol-Water Mixtures at 30° (Rel 69a, v 1, p 1112) (Various proportions of water were added to a mixt of 51.7% methanol and... 

Silica gel, per se, is not so frequently used in LC as the reversed phases or the bonded phases, because silica separates substances largely by polar interactions with the silanol groups on the silica surface. In contrast, the reversed and bonded phases separate material largely by interactions with the dispersive components of the solute. As the dispersive character of substances, in general, vary more subtly than does their polar character, the reversed and bonded phases are usually preferred. In addition, silica has a significant solubility in many solvents, particularly aqueous solvents and, thus, silica columns can be less stable than those packed with bonded phases. The analytical procedure can be a little more complex and costly with silica gel columns as, in general, a wider variety of more expensive solvents are required. Reversed and bonded phases utilize blended solvents such as hexane/ethanol, methanol/water or acetonitrile/water mixtures as the mobile phase and, consequently, are considerably more economical. Nevertheless, silica gel has certain areas of application for which it is particularly useful and is very effective for separating polarizable substances such as the polynuclear aromatic hydrocarbons and substances... 

The crude ketal from the Birch reduction is dissolved in a mixture of 700 ml ethyl acetate, 1260 ml absolute ethanol and 31.5 ml water. To this solution is added 198 ml of 0.01 Mp-toluenesulfonic acid in absolute ethanol. (Methanol cannot be substituted for the ethanol nor can denatured ethanol containing methanol be used. In the presence of methanol, the diethyl ketal forms the mixed methyl ethyl ketal at C-17 and this mixed ketal hydrolyzes at a much slower rate than does the diethyl ketal.) The mixture is stirred at room temperature under nitrogen for 10 min and 56 ml of 10% potassium bicarbonate solution is added to neutralize the toluenesulfonic acid. The organic solvents are removed in a rotary vacuum evaporator and water is added as the organic solvents distill. When all of the organic solvents have been distilled, the granular precipitate of 1,4-dihydroestrone 3- methyl ether is collected on a filter and washed well with cold water. The solid is sucked dry and is dissolved in 800 ml of methyl ethyl ketone. To this solution is added 1600 ml of 1 1 methanol-water mixture and the resulting mixture is cooled in an ice bath for 1 hr. The solid is collected, rinsed with cold methanol-water (1 1), air-dried, and finally dried in a vacuum oven at 60° yield, 71.5 g (81 % based on estrone methyl ether actually carried into the Birch reduction as the ketal) mp 139-141°, reported mp 141-141.5°. The material has an enol ether assay of 99%, a residual aromatics content of 0.6% and a 19-norandrost-5(10)-ene-3,17-dione content of 0.5% (from hydrolysis of the 3-enol ether). It contains less than 0.1 % of 17-ol and only a trace of ketal formed by addition of ethanol to the 3-enol ether. 

Figure 8-4. Fraction of total base present as hydroxide as a function of the percentage of water in the binary solvent, lor ethanol-water and methanol-water mixtures. ...

Electrodes and Galvanic Cells. The Silver-Silver Chloride Electrode. The Hydrogen Electrode. Half-cells Containing an Amalgam, Electrode. Two Cells Placed Back to Back. Cells Containing Equimolal Solutions. The Alkali Chlorides as Solutes. HC1 in Methanol or Ethanol Containing a Trace of Water. The Alkali Chlorides in Methanol-Water Mixtures. The Heal of Solution of HC1. Proton Transfer Equilibrium from Measurements of E.M.F. 

In the cells discussed in Sec. 57 the solvent in every case was water. But in this chapter we shall discuss cells placed back to back, where one solution contains a solute dissolved in water, while the other contains the same solute dissolved in ethanol, or in methanol, or in a methanol-water mixture. When, for example, a hydrogen electrode containing IIC1 dissolved in ethanol is coupled to a Ag/AgCl electrode, also containing HC1 dissolved in ethanol, the cell may be written... 

The highly electrophilic character of the POf ion would suggest a very unselective phosphorylation behavior. For example, the ratio of alkyl phosphate to inorganic phosphate obtained in hydrolyses of phosphoric esters in water/alcohol mixtures should reflect the molar ratio of water and alcohol. This is indeed found in numerous cases, e.g. in the hydrolysis of phenyl and 4-nitrophenyl phosphate monoanions 97) or of 4-nitrophenyl phosphate dianions 65) at 100 °C in methanol/ water mixtures of various compositions, as also in the solvolysis of the acetyl phosphate dianion at 37 °C 97) or of phosphoenol pyruvate monoanions 82). Calculations of the free energy of the addition reactions of water and ethanol to the POf ion support the energetic similarity of the two reactions 98) (Table 4). 

Neutral compounds can be extracted without controlling pH. Washing can be carried out with dilute acid or alkaline buffer (to remove ionisable impurities) and methanol water mixtures. The compounds can be eluted from the column with methanol, ethanol or chloroform. 

A suspension of 22.8 g (0.05 mol) of 2-(N-propargyl)-phthalimidoacetamido-5-chlorobenzophenone in 250 ml ethanol containing 7.5 g hydrazine hydrate (0.15 mol) was heated under reflux for 2 hours, at the end of which time the reaction mixture was set aside overnight at ambient (25°C) temperature. Thereafter, the crystalline phthalyl hydrazide which had precipitated out was removed by filtration and washed with 3 x 50 ml aliquots of chloroform. The filtrate and washings were diluted with water and exhaustively extracted with chloroform. The chloroform extract was then evaporated and the residue washed with 100 ml hexane to promote crystallization. The crude 7-chloro-l-propargyl-3H-l,4-benzodiazepine-2(lH)-one was recrystallized from a methanol-water mixture to give 10.5 g (71.4%) of the pure product. Melting point 140°C to 142°C. 

Although acid-base titrations in alcohol-water mixtures have been studied extensively, we do not consider them in detail since titration curves and indicator equilibria in ethanol-water and methanol-water mixtures can be calculated in the same way as in water. Values of the autoprotolysis constants of the mixtures, are close to for mixtures containing only a moderate amount of alcohol. On the other hand, even a trace of water in ethanol causes a large increase in J SH According to Gutbezahl and Grunwald, pXsH is 14.33, 14.88, 15.91, and 19.5 for ethanol-water mixtures containing 20, 50, 80, and 100 wt % ethanol. 

A particularly useful preparation of DHA, described by Ohmori and Takagi, uses oxygen oxidation over a charcoal catalyst (6). The use of oxygen and charcoal to convert AA to DHA is a well-known reaction that has been used in AA assays for many years. The oxidation can be made in ethanol, methanol, water, or various mixtures of these solvents. We carry out this procedure as follows ... 

Properties Crystals from methanol-water mixture. Mp 222C. Soluble in water insoluble in methanol and ethanol. 

The electrochemical reactions proceed in ethanol-water or methanol-water mixtures. Alternatively, gas diffusion electrodes can be used. 

Alumina and titania in different solvents were studied in [822]. MgO and ZnO in seven organic liquids were studied in [1686]. Silica in a series of nonaqueous solvents and in acetonitrile-water and methanol-water mixtures was studied in [3139,3140]. Only positive potentials are reported, probably by mistake. Silica in decane was studied in [3141]. ZnO in absolute methanol, ethanol, and propanol was studied in [3142]. Montmorillonite in 2-propanol was studied in [3143]. Silicon in a 99% l-butanol-1% water mixture was studied in [3145]. In [3146], 11 solids (oxides and inorganic salts) in 9 solvents were studied. 

Silica in 80-95% dioxane in the presence of HCI, KOH, and different 1 1 salts was studied in [314]. Silica in nonaqueous solvents containing 1 mass% of water in the presence of CsCl was studied in [3155]. Silica in methanol in the presence of KCl was studied in [282]. Quartz in DMSO in the presence of various 1-1 electrolytes was studied in [3156]. Quartz in ethanol in the presence of various 1-1 electrolytes was studied in [3157,3158]. Quartz in DMSO, acetone, and 1-butanol in the presence of NaBr or LiBr was studied in [3151]. Silica in methanol, acetonitrile, and methanol-water mixtures, with or without NaCl was studied in [1853]. Silica in 99.7% acetone in the presence of Nal and BU4NI was studied in [1908]. Titania in different 99% organic-1% water mixtures in the presence of CsCl and other 1-1 salts was studied in [3160]. Anatase in different organic solvents in the presence of CsOH and HCIO4 was studied in [3161].Titania in -alcohols in the presence of different salts was studied in [2037]. LIF, Cal 2, and MgF, in methanol, acetone, and nitroethane in the presence of NaF were studied in [3162]. Agl in ethanol at concentrations of LiNQ, up to 0.01 M was studied in [3163]. ("aSiO, in DMSO at different concentrations of NaBr and CaBr2 was studied in [3144]. Diamond in 96% ethanol in the presence of various 1-1 salts was studied in [3164]. 

Materials with immobilised mercaptopropyl groups were oxidised with H2O2 in a methanol-water mixture. Typically 2.04 g of aqueous 35% H2O2 dissolved in three parts of methanol was used per gram of material. After 24 hours the mixture was filtered and washed with water and ethanol. The wet material was then re-suspended in 0.1 M H2SO4 solution for another 4 hours. Finally, the material was rinsed with water and dried at 60 C under vacuum. ... 

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