Ethanol water removal

Filter the mixed product at the pump, and wash it well with ethanol to remove excess of dimedone, and then with water and again with ethanol. The dried white residual methylene-dimedone , m.p. 186-188°, weighs o 55-o-65 g. It may be recrystallised from ethanol containing about 10% of water, and then has m.p. 189°. 

Esterifica.tlon. The process flow sheet (Fig. 4) outlines the process and equipment of the esterification step in the manufacture of the lower acryflc esters (methyl, ethyl, or butyl). For typical art, see References 69—74. The part of the flow sheet containing the dotted lines is appropriate only for butyl acrylate, since the lower alcohols, methanol and ethanol, are removed in the wash column. Since the butanol is not removed by a water or dilute caustic wash, it is removed in the a2eotrope column as the butyl acrylate a2eotrope this material is recycled to the reactor. 

Pervaporation is a relatively new process with elements in common with reverse osmosis and gas separation. In pervaporation, a liquid mixture contacts one side of a membrane, and the permeate is removed as a vapor from the other. Currendy, the only industrial application of pervaporation is the dehydration of organic solvents, in particular, the dehydration of 90—95% ethanol solutions, a difficult separation problem because an ethanol—water azeotrope forms at 95% ethanol. However, pervaporation processes are also being developed for the removal of dissolved organics from water and the separation of organic solvent mixtures. These applications are likely to become commercial after the year 2000. 

The hquid product streams are fed to a distillation system to remove the light impurities and to recover the ethanol as a 95% volume ethanol—water a2eotrope. To produce anhydrous ethanol, the ethanol—water a2eotrope is fed to a dehydration system. 

Alumina sufficient to adsorb the complete solution is added, then the solvent is removed under vacuum. While benz[a]anthracene, np 157-158°C, sufficiently pure for most purposes, can be obtained by crystallization of the crude product from ethanol-water, filtration" through alumina removes residual, colored impurities, affording a pure, white product. 

Cellulose for chromatography is purified by sequential washing with chloroform, ethanol, water, ethanol, chloroform and acetone. More extensive purification uses aqueous ammonia, water, hydrochloric acid, water, acetone and diethyl ether, followed by drying in a vacuum. Trace metals can be removed from filter paper by washing for several hours with O.IM oxalic or citric acid, followed by repeated washing with distilled water. 

At the conclusion of the reflux period, ethanol is removed on a rotary evaporator. Sulfuric acid (200 ml of 2 A solution) is added to the residue, and the mixture is stirred for 3-4 hours. The solid product is collected by filtration, washed with several portions of water, and allowed to dry in the air. It is then dissolved in 150 ml of boiling ethyl acetate, then filtered hot. The filtrate is cooled in ice, affording 16-17 g of 2,5-dicarbethoxy-l,4-cyclohexanedione, mp 126-129° as off-white crystals. 

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. 

Preparation of 1-Methyl-5-Allyl-5-( 1-Methyl-2-Pentynyl) Barbituric Acid A solution of 23.8 g of sodium in 360 ml of absolute alcohol was prepared and thereto were added 38.3 g of methyl urea and 96.8 g of diethyl allyl (1-methyl-2-pentynyl) malonate. The mixture was refluxed for about 20 hours, cooled, and the ethanol was removed by distillation in vacuo. The residue was dissolved in about 300 ml of water and the aqueous solution was washed with ether, and the washings were discarded. The aqueous solution was then acidified with acetic acid, and extracted with three 150 ml of portions of ether. 

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 ... 

B. Determination of tellurium Procedure. The solution should contain not more than 0.2 g tellurium in 50 mL of 3M hydrochloric acid (ca 25 per cent by volume of hydrochloric acid). Heat to boiling, add 15 mL of a freshly prepared, saturated solution of sulphur dioxide, then 10 mL of a 15 per cent aqueous solution of hydrazinium chloride, and finally 25 mL more of the saturated solution of sulphur dioxide. Boil until the precipitate settles in an easily filterable form this should require not more than 5 minutes. Allow to settle, filter through a weighed filtering crucible (sintered-glass, or porcelain), and immediately wash with hot water until free from chloride. Finally wash with ethanol (to remove all water and prevent oxidation), and dry to constant weight at 105 °C. Weigh as Te. 

Fig. 7.2.1 Absorption spectra of Odontosyllis luciferin (solid line) and Odontosyllis oxyluciferin (dashed line), both in ethanol/water (5 6) containing 8% NaCl. To measure the latter curve, luciferin was first luminesced in the presence of luciferase, then luciferase was removed using a small column of DEAE cellulose. From Shimomura et al, 1963d, with permission from John Wiley Sons Ltd.

The procedure for determination of neutral oils in AOS measures petroleum spirit-extractable material from an aqueous alcoholic solution. Normally a solution of 1 1 ethanol/water is used as to dissolve the sample prior to extraction. For higher molecular weight materials 2 1 propan-2-ol/water is preferred. The petroleum ether is removed on a steambath and finally under vacuum. The amount of neutral oil is then determined gravimetrically. Due to the slight volatility of alkenes, alkanes, and alcohols, especially in the C,2 materials, the neutral oil tends to be underestimated by these procedures. 

The simplest and cheapest procedure to obtain standards is based on selective extraction followed by crystallization. A method developed to obtain lycopene from tomato residue using factorial experimental design consisted of a preliminary water removal with ethanol, followed by extraction with EtOAc and two successive crys-talhzation processes using dichloromethane and ethanol (1 4), producing lycopene crystals with 98% purity, measured by HPLC-PDA. Using this approach, bixin was extracted with EtOAc from annatto seeds that were previously washed with... 

Volkov (1994) has given a state-of-the-art review on pervaporation. A number of industrial plants exist for dehydration of ethanol-water and (.vwpropanol-water azeotropes, dehydration of ethyl acetate, etc. There is considerable potential in removing dissolved water from benzene by pervaporation. The recovery of dis.solved organics like CH2CI2, CHCI3, CCI4, etc. from aqueous waste streams also lends itself for pervaporation and pilot plants already exist. 

Similarly, Kou et al. published the synthesis of PVP-stabilized noble-metal nanoparticles in ionic liquids BMI PF6 at room temperature [76]. The metal nanoparticles (Pt, Pd, Rh) were produced by reduction of the corresponding metal halide salts in the presence of PVP into a refluxing ethanol-water solution. After evaporation to dryness the residue was redissolved in methanol and the solution added to the ionic liquid. The methanol was then removed by evaporation to give the ionic liquid-immobilized nanoparticles. These nanoparticles were very stable. TEM ob-... 

The partition of different lipids between two immiscible solvents (countercurrent distribution) is useful for crude fractionation of lipid classes with greatly differing polarities. Repeated extractions in a carefully chosen solvent pair increase the effectiveness of the separation but in practice mixtures of lipids are still found in each fraction. A petroleum ether-ethanol-water system can be used to remove polar contaminants (into the alcoholic phase) when interest lies in the subsequent analysis of neutral glycerides, which may be recovered from the ether phase. Carbon... 

A simple TLC method has been developed for the separation and identification of flavons and flavon glycosides in the extract of Phillyrea latifolia L. The leaves (100 g) were defatted in 11 of chloroform for 24 h and then extracted with 2 X 11 of ethanol-water (80 20, v/v). The collected extracts were concentrated and extracted again with n-hexane to remove chlorophylls and other apolar constituents. Analytes were extracted with ethyl acetate. Both normal phase and RP-TLC have been used for the separation of flavonoids. The results are compiled in Table 2.36. It was concluded from the data that TLC can be successfully applied for the quality control of plant extracts containing various flavone derivatives [124],... 

In the analysis of water, the use of ethanol to remove more than traces of nitrate or nitrite ion may lead to formation of fulminic acid, and if mercury(II) is used as a catalyst, explosive mercury fulminate may be formed. 

The first tower in Figure 11.44 gives the ternary azeotrope as an overhead vapour, and nearly pure ethanol as bottom product. The ternary azeotrope is condensed and splits into two liquid phases in the decanter. The benzene-rich phase from the decanter serves as reflux, while the water-ethanol-rich phase passes to two towers, one for benzene recovery and the other for water removal. The azeotropic overheads from these successive towers are returned to appropriate points in the primary tower. 

B. 1,4-Cyclohexanedione. The purified 2,5-dicarbethoxy-l,4-cyclohexanedione (170 g., 0.66 mole) (Note 5) and 170 ml. of water are placed in a glass liner (vented) of a steel pressure vessel of 1.5-1. capacity (fitted with a pressure-release valve). The vessel is sealed, heated as rapidly as possible to 185-195°, and kept at this temperature for 10-15 minutes (Note 6). The reaction vessel is immediately removed from the heater, placed in a large tub of ice water, and cooled to room temperature. The gas pressure then is carefully released. The resulting yellow to orange liquid is transferred to a distillation flask with the aid of a minimum volume of ethanol, and most of the water and ethanol is removed under reduced pressure by means of a rotary evaporator. The flask is attached to a short heated column fitted with a short air condenser. The remainder of the water and ethanol is removed under reduced pressure, and the 1,4-cyclohexanedione is distilled, b.p, 130-133° (20 mm.). The product solidifies to a white to pale-yellow solid, m.p. 77-79°, deld 60-66 g. (81-89% yield from 2,5-dicarbethoxy-l,4-cyclohexanedione). The compound may be conveniently recrystallized from carbon tetrachloride (7 ml. per gram of dione) the purified product is obtained as white plates, m.p. 77-79° (90% recovery). 

At the end of the 24-hour period, the ethanol is removed under reduced pressure on a steam bath. A 2N sulfuric acid solution (2 1.) is added to the warm residue, and the mixture is stirred vigorously for 3—4 hours (Note 3). The solid is removed by suction filtration and washed several times with water. The air-dried product is a pale-bufi powder weighing 180-190 g., m.p. 126-128°. The solid is added to 1.5 1. of ethyl acetate, the mix-... 

The other change that needed to be made in the synthesis of RSR 13 for in vivo administration was the method of purification. RSR 13 is used in vivo as the sodium salt. I prepared the first batch for in vivo toxicology by triturating RSR 13 sodium salt with acetone to remove any vestiges of water. However, the first industrial scale-up procedure called for crystallization of the salt from ethanol-water. The ethanol-water crystals were not as soluble as the acetone triturated method and could not be formulated at a reasonable volume. We performed the crystal structure determination of the ethanol-water crystals and found that it was a heptahydrate (Figure 17.5) [50]. The problem for large-scale production of RS R13 was solved eventually by the industrial producers of RSR 13. 

Examples of solvent-mediated transformation monitoring include the conversion of anhydrous citric acid to the monohydrate form in water [235,236], CBZ with water [237] and ethanol-water mixtures [238,239], and cocrystallization studies of CBZ, caffeine, and theophylline with water [240]. Raman spectroscopy was used to monitor the crystallization rate and solute and solvent concentrations as griseofulvin was removed from an acetone solution using supercritical CO2 as an antisolvent [241]. Progesterone s crystallization profile was monitored as antisolvent was added [242]. 

The organic phase is removed by applying a positive air pressure to the extraction vessel, thus forcing the extract up a PTFE tube and through a probe into a glass, or polypropylene, extract collection vessel situated in the extract collection module. During the washing cycle, the tube and probe are washed out with ethanol—water and then blown dry with air. 

The partial oxidation of ethanol was investigated, but with less intensity than in the case of steam reforming. The reason is that the use of the pure partial oxidation process is not advised for bioethanol reforming because bioethanol is an ethanol-water mixture in which removal of all the water entails a significant cost. Therefore, for bioethanol partial oxidation, the process is combined with steam reforming in autothermal schemes with the stoichiometry shown in Equation 6.18. 

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