Water + ethanol mixtures

Filter the crystals at the pump, wash them with water, and drain well. To save time, the product may be recrystallised directly from an ethanol-water mixture (1 2 by vol.), and obtained as colourless crystals, m.p. 68°. Alternatively, the crude product can be dried in a desiccator (yield of dry product, I-9-2 0 g., m.p. 65-67°) and recrystallised from petroleum (b.p. 60-80°), and obtained as needles, m.p. 68°. 

Fig. 42. Integrated distillation/pervaporation plant for ethanol recovery from fermentors. The distillation columns concentrate the ethanol—water mixture from 5 to 80%. The pervaporation membrane produces a 99.5% ethanol product stream and a 40—50% ethanol stream that is sent back to the distillation...

Table 2. Solubility of Coumarin in Ethanol-Water Mixtures ...

A typical apphcatiou of a simple batch still might be distillation of an ethanol-water mixture at 101.3 kPa (1 atm). The initial charge is 100 mol of ethanol at 18 mole percent, aud the mixture must be reduced to a maximum ethanol concentration in the stiU of 6 mole percent. By using equilibrium data interpolated from Table 13-1,... 

To illustrate the use of these equations, consider a charge of 520 mol of an ethanol-water mixture containing 18 mole percent ethanol to be distilled at 101.3 kPa (1 atm). Vaporization rate is 75 moFh, and the product specification is 80 mole percent ethanol. Let L/V = 0.75, corresponding to a reflux ratio R = 3.0. If the system has seven theo-... 

Because of their zwitterionic nature, amino acids are generally soluble in water. Their solubility in organic solvents rises as the fat-soluble portion of the molecule increases. The likeliest impurities are traces of salts, heavy metal ions, proteins and other amino acids. Purification of these is usually easy, by recrystallisation from water or ethanol/water mixtures. The amino acid is dissolved in the boiling solvent, decolorised if necessary by boiling with Ig of acid-washed charcoal/lOOg amino acid, then filtered hot, chilled, and set aside for several hours to crystallise. The crystals are filtered off, washed with ethanol, then ether, and dried. 

Potassium hydrogen malate [4675-64-3] M 172.2. A saturated aqueous solution at 60° was decolorised with activated charcoal, and filtered. The filtrate was cooled in water-ice bath and the salt was ppted by addition of EtOH. After being crystallised five times from ethanol-water mixtures, it was dried overnight at 130° in zir [Edenand Bales J Res Nat Bur Stand 62 161 1959],... 

There is much evidence that there are many cases in which the interaction between liquids and solids cannot be described in terms of dispersion forces alone. For example, Dann [75] found significant non-dispersion-force contributions to the work of adhesion between ethanol/water mixtures, mixed glycols, and polyglycols and a mixture of formamide and 2-ethoxyethanol against a variety of solids. The nature of these other interactions , however, were at first the subject of some dispute. We may account for them in a general way with a term /sl inserted into Eq. 11 ... 

In some cases the column construction used does not support a movable adapter, e.g., the popular stack column (see Section V) where a stable bed is achieved by shrinking the gel slightly in an ethanol-water mixture prior to packing. After the column is packed and the column has been closed the gel is allowed to expand by equilibrating the column in distilled water. 

Wines and other alcoholic beverages such as distillates represent very complex mixtures of aromatic compounds in an ethanol-water mixture. Once an extract or concentrate of the required compounds is prepared, a suitable chromatographic system must be used to allow separation and resolution of the species of interest. Many applications have been developed that use MDGC. 

This Crude product (15.8 g) In water (360 ml) was added to a prehydrogenated suspension of 10% palladium on charcoal (4 g) in water (400 ml), and hydrogenation was continued for 30 minutes. The catalyst was removed and the filtrate was adjusted to pH 7.5 with sodium bicarbonate, then evaporated at low temperature and pressure. The residue was purified by chromatography on a column of cellulose powder, eluting first with butanol/ ethanol/water mixture and then with acetone/isopropanol/water. The main fraction was evaporated at low temperature and pressure to give a 32% yield of the sodium salt of a-carboxybenzylpenicillin as a white powder. The product was estimated by manometric assay with penicillinase to be 58% pure. 

Figure 8-37. x-y diagram for ethanol-water mixture, showing minimum reflux. Used by pemiission, Block, B. Chem. Eng. Feb. 6 (1961), p. 87. 

Maleic anhydride is also a precursor for 1,4-butanediol through an esterification route followed by hydrogenation. In this process, excess ethyl alcohol esterifies maleic anhydride to monoethyl maleate. In a second step, the monoester catalytically esterifies to the diester. Excess ethanol and water are then removed by distillation. The ethanol-water mixture is distilled to recover ethanol, which is recycled ... 

Procedure. Weigh out accurately about 4 g of the pure organic acid, dissolve it in the minimum volume of water (Note 1), or 1 1 (v/v)ethanol/water mixture, and transfer the solution to a 250 mL graduated flask. Ensure the solution is homogeneous and make up to the required volume. Use a pipette to measure out accurately a 25 mL aliquot and transfer to a 250 mL conical flask. Using two drops of phenolphthalein solution as indicator, titrate with standard 0.2M (approx.) sodium hydroxide solution (Note 2) until the colourless solution becomes faintly pink. Repeat with further 25 mL volumes of the acid solution until two results in agreement are obtained. 

The results for (cyclohexane + decane) are obtained from J. R. Goates. J. R. Ott, and R. B. Grigg, "Excess Volumes of Cyclohexane 4- u-Hexane. +u-Heptane, -t-n-Octane, + -Nonane, and +u-Decane", J. Chem. Thermodyn.. 11. 497-506 (1979). Excess volumes for the (ethanol + water) system were obtained from K. N. Marsh and A. E. Richards, Excess Volumes for Ethanol + Water Mixtures at 10-K intervals from 278.15 to 338.15 K", Ausr. J. Chem., 33, 2121-2132 (1980). Excess volumes for the (acetonitrile + benzene) and the (hexane + decane) systems were obtained from the same source as the HG and results referenced earlier. 

The auto-thermal reaction of ethanol occurred in the shell side of a palladium membrane reactor in which a Zn-Cu/AlaOs industrial catalyst (MDC-3) was packed with silica powder. Ethanol-water mixture (nH2o/nEioH=l or 3) and oxygen (noa/nEioH=0.2,0.776 or 1.035) are fed concurrently to the shell side. The reaction temperatures were set at 593-723 K and the pijrasures were 3 10 atm. 

Since it is well known that the higher the olefin, the more difficult it is to hydroformylate, we tried our approach on 1-dodecene. We found that when we used 50 50 ethanol/water (R24) and CTAB only (R33) systems they showed no activity for hydroformylation of 1-dodecene whereas, the addition of surfactant to the 50 50 ethanol/water mixture (R27) dramatically increased the reaction rate, as well as the selectivity. 

The oxidative cleavage of v/c-diols to give two carbonyl functions (Eq. 5.3) by periodates was first observed by Malaprade and has since been widely applied to the carbohydrate area.50 Since both the reagent sodium periodate and the carbohydrate substrate are water soluble, the reaction is usually carried out in aqueous media.51 The reaction has been applied to polysaccharides such as starch.52 The periodate oxidations of sodium alginate in water as well as a dispersion in 1 1 ethanol-water mixture have been compared.53 Because sodium alginate forms a highly viscous solution, the oxidation was observed to be more extensive in ethanol-water. 

Esteso, M. A. Gonzalez-Diaz, O. M. Hemandez-Luis, F. F. Femandez-Merida, L., Activity coefficients forNaCl in ethanol-water mixtures at 25°C, J. Solut. Chem. 18,277-288 (1989). 

Hawes, J. L. Kay, R. L., Ionic association of potassium and cesium chloride in ethanol-water mixtures from conductance measurements at 25°, J. Phys. Chem. 69, 2420-2431 (1965). 

Pervaporation. Pervaporation differs from the other membrane processes described so far in that the phase-state on one side of the membrane is different from that on the other side. The term pervaporation is a combination of the words permselective and evaporation. The feed to the membrane module is a mixture (e.g. ethanol-water mixture) at a pressure high enough to maintain it in the liquid phase. The liquid mixture is contacted with a dense membrane. The other side of the membrane is maintained at a pressure at or below the dew point of the permeate, thus maintaining it in the vapor phase. The permeate side is often held under vacuum conditions. Pervaporation is potentially useful when separating mixtures that form azeotropes (e.g. ethanol-water mixture). One of the ways to change the vapor-liquid equilibrium to overcome azeotropic behavior is to place a membrane between the vapor and liquid phases. Temperatures are restricted to below 100°C, and as with other liquid membrane processes, feed pretreatment and membrane cleaning are necessary. 

Figure 12.22 Distillation sequence for the separation of an ethanol-water mixture using ethylene glycol as entrainer is infeasible using single-feed column.

Noskov S Y, Lamoureux G, Roux B (2005) Molecular dynamics study of hydration in ethanol-water mixtures using a polarizable force field. J Phys Chem B 109(14) 6705-6713... 

FIGURE 8.5 Absorption spectra of zeaxanthin dissolved in pure ethanol (solid line), in ethanol/water mixture with 1 4 ratio (dotted line), and in 3 2 ethanol/water mixture. Minor bands of the H-aggregate are denoted by. ... 

When we perform experiment in such way that there is no interference of H-bonds or these bonds are stable and structure of solvent also does not varies essentially, solvatochromic plot demonstrates very good linearity as shown, for example, for some naphthylamine derivatives in ethanol-water mixtures. The linearity of solvatochromic plots is often regarded as an evidence for the dominant importance of nonspecific universal intermolecular interaction in the spectral shifts. Specific solvent effects lead to essential deviation of measured points from this linear plot. 

Cohn, E.J. et al. (1947) Preparation and properties of serum and plasma proteins. XIII. Crystallization of serum albumins from ethanol-water mixtures./. Am. Chem. Soc. 69, 1753-1761. 

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