Chloroform-acetone-water mixture

Mixtures of phosphoglycerides can be separated using a chloroform-methanol-water mixture, the proportions of which may be varied to suit the sample constituents (e.g. 65 25 4). Acetone is sometimes included in the solvent and silver nitrate-impregnated plates can be used. Acetic acid (1-4%) is also a useful additive to effect the separation of neutral phosphoglycerides... 

Two hundred cubic centimeters of an acetone-water mixture that contains lO.O wt% acetone is mixed with 400.0 cm of chloroform at 25 C. and the phases are then allowed to settle. What percentage of the acetone is transferred from the water to the chloroform ... 

Most papers dealing with phenolic acid HPLC analysis in herbs describe only simple liquid extraction without the hydrolysis step. Acetone, methanol, or alcoholic-water or acetone-water mixtures are applied. Very rarely, pure water is used as the extraction solvent. " It was found that the extraction recoveries for water extracts are often lower in comparison to alcoholic-water mixtures, especially when the simultaneous separation of polar and less polar phenolic acids has been performed. Sometimes, the control of pH can improve the recovery. If necessary, n-hexane, chloroform, diethyl ether, benzene-acetone, petroleum ether, or other less polar solvents are recommended for removing interfering compounds. The extraction is usually performed by refluxing the samples for a specific time in a Soxhlet apparatus, with simple mechanical or magnetic stirring of the sample with the extraction solvent, or by plant sample maceration. The application of an ultrasonic bath for the liquid extraction has also become popular in recent years. The hydrolysis steps have also been recommended for medicinal species preparation, especially when other phenolic compounds are also analyzed simultaneously with phenolic acids in herbs. 

The lyso-glycerophospholipids are insoluble in ether, petroleum ether and absolute acetone, but soluble in water, chloroform, and acetone-water mixtures. 

The introduction of polar groups such as carboxylic acid groups modified polymer physical properties. As reported in Table 4, PHOioo-xUx samples are soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, but are insoluble in polar solvents such as methanol, acetone/water 85/15 (v/v). After oxidation PHO90U10 and PH09oDio(cooh) behaved differently in acetone/water solvent. More clearly, contrary to PHO75U25, PH075D25(cooh) was soluble in methanol, acetone, and in different acetone/water mixtures. 

Over a period of hours, 1.65 g lithium (3.27 eq) is added in small portions until a permanent blue color is obtained. The blue reaction mixture is then treated with 38 g of triethyl-amine hydrochloride. The ammonia is allowed to evaporate at room temperature overnight and the residual solvent is evaporated at reduced pressure. The white residue is taken up in a small amount of methanol-water and added to 4 liters of cold 1 1 chloroform-acetone to precipitate the crude product. After 20 minutes stirring the suspension is filtered and the while filler cake dried in vacuo the filler cake is then pulverized and submitted once more to the precipitation process from 1 1 chloroform-acetone. 

The new lipid occurred only in the plasma hpids of newborns and was not present in membrane hpids of red cell membranes or platelets. Total lipids were extracted from plasma and from red blood cell membranes and platelets. A total lipid profile was obtained by a three-directional PLC using silica gel plates and was developed consecutively in the following solvent mixtures (1) chloroform-methanol-concen-trated ammonium hydroxide (65 25 5, v/v), (2) chloroform-acetone-methanol-ace-tic acid-water (50 20 10 15 5, v/v), and (3) hexane-diethyl ether-acetic acid (80 20 1, v/v). Each spot was scraped off the plate a known amount of methyl heptadecanoate was added, followed by methylation and analysis by GC/MS. The accmate characterization of the new lipid was realized using NMR technique. 

The most critical decision to be made is the choice of the best solvent to facilitate extraction of the drug residue while minimizing interference. A review of available solubility, logP, and pK /pKb data for the marker residue can become an important first step in the selection of the best extraction solvents to try. A selected list of solvents from the literature methods include individual solvents (n-hexane, " dichloromethane, ethyl acetate, acetone, acetonitrile, methanol, and water ) mixtures of solvents (dichloromethane-methanol-acetic acid, isooctane-ethyl acetate, methanol-water, and acetonitrile-water ), and aqueous buffer solutions (phosphate and sodium sulfate ). Hexane is a very nonpolar solvent and could be chosen as an extraction solvent if the analyte is also very nonpolar. For example, Serrano et al used n-hexane to extract the very nonpolar polychlorinated biphenyls (PCBs) from fat, liver, and kidney of whale. One advantage of using n-hexane as an extraction solvent for fat tissue is that the fat itself will be completely dissolved, but this will necessitate an additional cleanup step to remove the substantial fat matrix. The choice of chlorinated hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride should be avoided owing to safety and environmental concerns with these solvents. Diethyl ether and ethyl acetate are other relatively nonpolar solvents that are appropriate for extraction of nonpolar analytes. Diethyl ether or ethyl acetate may also be combined with hexane (or other hydrocarbon solvent) to create an extraction solvent that has a polarity intermediate between the two solvents. For example, Gerhardt et a/. used a combination of isooctane and ethyl acetate for the extraction of several ionophores from various animal tissues. 

In a similar way, one can achieve the separation according to functionality in other solvent mixtures, e.g. chloroform-acetone (Fig. 17). Except of slight differences in retention times for molecules of different functionality, which can be caused either by the difference in the interaction in the mobile phase or a change in the water content of the adsorbent, the form of FTD chromatograms for both eluents at critical conditions is similar. This indicates that for the critical conditions to be realized it is sufficient to have any two solvents suitable for the detection method, one of which works in the exclusion and the other in the adsorption mode. 

Hudson et a/.151,152 have concluded that the bimolecular solvolysis of ethyl chloroformate involves heterolysis of the carbon-chlorine bond and not heterolysis of the carbon-oxygen bond. Their data shows that the hydrolysis of ethyl chloroformate is a second-order reaction in water/acetone mixtures, methyl chloroformate reacting about 2.2 times as fast in 65% water/acetone at 50°C. Hydroxide ion accelerates the reaction (3.1 x 107 in 18% water/ acetone and 3.4 x 108 in 85% water/acetone) and catalysis by hydroxide ion was observed with pure water as solvent by Hall118. There is some disagreement about the value for the hydrolysis rate coefficient for ethyl chloroformate in water and in other solvents (Table 21). To date, the data of Queen153 (for pure water), Kivinen92 (for ethanol) and Liemiu101 (for methanol) must be considered the most accurate. 

A solution of 2 (246 mg, 0.9 mmol) in 2.5 mL of a mixture of acetone, water, and sulfuric acid (96 4 0.25) was left at room temperature for 40 min, whereupon the solution was neutralized with solid lead carbonate (ca. 300 mg). The suspension was filtered, the solid was washed with acetone, and to the filtrate water (10 mL) was added. Acetone was evaporated, and the residue was extracted with chloroform. The CHC13 extract was dried (MgS04) and concentrated to dryness to yield 3 (167 mg, 83%). 

The solubility of NHDC in hot water, alcohol, aqueous alkali, acetonitrile, dimethyl sulfoxide, and alcohol/water mixture facilitates its selective extraction from food samples (20,91,94). It is extracted from jams, fruit juices, and dairy products with methanol (66,93) or acetone (95) and filtered or centrifuged. Chewing gum samples are dissolved in chloroform and extracted with water. The extract is centrifuged, and the clear supernatant is injected into the HPLC (95). If necessary, sample cleanup and concentration may be achieved by selective adsorption or desorption (20) on Sep-Pak Cl8 (96). Tomas-Barberan et al. (93) used Amberlite XAD-2 resin for purification of jam extract. Sugars, pectin, and other polar compounds were eluted with water, and NHDC was eluted with methanol. After concentration, the extract was further purified on a Sephadex LH-20 column prior to HPLC analysis. 

The dimer-rich fractions were adsorbed on 30 parts of Woelm alumina, activity grade IV (i.e., alumina containing 10% water) and eluted first with mixtures of chloroform and cyclohexane and on a second pass with benzene and cyclohexane. Occasionally, acetone-cyclohexane mixtures were used for better separation of alcohols and dimers and nylon powder chromatography for ultimate purification. Even at a 30 1 (alumina lignin) weight... 

A solution of S-iodomethyl-6a,9a-difluoro-lip-hydroxy-16a-methyl-3-oxo-17a-propionyloxyandrosta-l,4-diene-17p-carbothioate (310 mg) in acetonitrile (10 ml) was stirred with silver fluoride (947 mg) for 3 days at room temperature in the dark. Ethyl acetate (100 ml) was added and the mixture was filtered through kieselguhr. The filtrate was washed successively with 2 N hydrochloric acid, water, saturated brine, then dried. The solvent was removed and the residue was subjected to column chromatography in chloroform then chloroform-acetone (19 1). The product was eluted with ethyl acetate and crystallised on concentration of the solution to give S-fluoromethyl 6a,9a-difluoro-lip-hydroxy-16a-methyl-3-oxo-17a-propionyloxyandrosta-l,4-diene-17p-carbothioate (0.075 g) melting point 272-273°C (dec.), [a]D= +30° (c 0.35). 

To a solution of 28.91 g of 3-fluoro-4-morpholinyl-aniline and 27.88 g of sodium bicarbonate in 500 mL of acetone and 250 mL of water at 0°C was added 28.68 g of benzyl chloroformate. After stirring the mixture for 1.5 hours, the mixture was poured onto 1 L of ice and water, and the ice allowed to melt. The precipitated solid was collected by filtration and washed with of water, and then dried in a vacuum oven at 75°C to give a gray-purple solid. This was recrystallized from acetone-water to give a cream-colored solid of N-carbobenzyloxy-3-fluoro-4-morpholinylaniline, m.p. = 123-124°C. 

To a mixture of 4.2 g (0.0083 mole) of 4 -tert-butyl-4-[4-(a-hydroxy-a-phenylbenzyl)piperidino]-butyrophenone hydrochloride and 0.54 g (0.01 mole) of sodium methoxide in 25 ml of methanol is added 2.16 g (0.04 mole) of potassium borohydride. The reaction mixture is stirred overnight, diluted with water and the methanol removed under reduced pressure. The remaining material is extracted with chloroform, washed with water, dried over magnesium sulfate and filtered. The filtrate is concentrated, and the residue is recrystallized from acetone-water to give 4-[a-(p-tert-butylphenyl)-a-hydroxybenzyl]-a-phenyl-l-piperidinebutanol, melting point 161°-163°C. 

For isolation of la, filter the suspension, which should be once again almost colourless, on a Buchner funnel and wash the remaining solid with ether. Recrystallize it first from minimum amount of water, and then from chloroform/acetone mixtures to obtain pure 1a, m.p. 271°C, 7.5 g (94%). For the preparation of 2, the ethereal suspension resulting from step 4 can be used right away. 

Method. Take two 20-ml screw-capped glass bottles (McCartney bottles) and to the first add 10 ml of the urine and 3 ml of hydrochloric acid, and to the second add 9 ml of blank urine, 1 ml of the reference solution, and 3 ml of hydrochloric acid. Screw on the caps and heat the bottles in a boiling water-bath for 15 minutes. Cool the solutions, add to each bottle 10 ml of petroleum spirit (b.p. 40°-60°), shake for 5 minutes, and centrifuge. Transfer the solvent layers to 10-ml conical test-tubes, evaporate to dryness under a stream of air or nitrogen, and dissolve die residues in 0.1 ml of methanol. Divide a TLC plate (silica gel G, 250 pm) into two equal columns and apply 50 pi of each exhact to die plate. Develop the plate in a tank containing a 4 1 mixture of chloroform acetone (System TD, p. 168). After development, dry die plate in a stream of cold air. 

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... 

If a third substance is added to a two-phase liquid mixture, it distributes itself according to its relative solubility in each phase. For example, acetone is soluble in both water and chloroform—two nearly immiscible liquids—but much more so in chloroform. If a mixture of acetone and water is contacted with chloroform, a substantial portion of the acetone enters the chloroform-rich phase. Separation of the acetone and water may then be accomplished easily by allowing the mixture to settle and separating the two phases. This example illustrates the separation process of liquid extraction. 

---