Extraction with solvents


EXTRACTION WITH SOLVENTS  [c.44]

The process of extraction with solvents is generally employed either for the isolation of dissolved substances from solutions or from solid mixtures or for the removal of undesired soluble impurities from mixtures. The latter process is usually termed washing.  [c.44]

TECHNIQUE OF EXTRACTION WITH SOLVENTS  [c.149]

Aromatic and Nonaromatic Hydrocarbon Separation. Aromatics are partially removed from kerosines and jet fuels to improve smoke point and burning characteristics. This removal is commonly accompHshed by hydroprocessing, but can also be achieved by Hquid-Hquid extraction with solvents, such as furfural, or by adsorptive separation. Table 7 shows the results of a simulated moving-bed pilot-plant test using siHca gel adsorbent and feedstock components mainly in the C q—range. The extent of extraction does not vary gready for each of the various species of aromatics present. SiHca gel tends to extract all aromatics from nonaromatics (89).  [c.300]

The polymer is then dried thoroughly and stored for subsequent processing. Whenever a polyester is made by melt polycondensation, a small amount of cycHc oligomer is formed which is in equiHbrium with the polymer. This can be extracted with solvents from soHd polymer but when the  [c.294]

Many attempts have been made to reduce the ammoniacal and sulfurous odor of the standard thioglycolate formulations. As the cosmetics market is very sensitive to the presence of impurities, odor, and color, various treatments of purification have been claimed to improve the olfactory properties of thioglycolic acid and its salts, such as distillation (33), stabilization against the formation of H2S using active ingredients (34), extraction with solvents (35), active carbon (36), and chelate resin treatments (37).  [c.5]

Aniline will be used as a second example. It has a pK of 4.60 at 25° in H2O. If it is placed in aqueous solution at pH 1.60 it will exist almost completely (99.9%) as the anilinium cation. This solution can then be extracted with solvents e.g. diethyl ether to remove neutral impurities. The pH of the solution is then adjusted to 7.60 whereby aniline will exist as the free base (99.9%) and can be extracted into diethyl ether in order to give purer aniline.  [c.7]

Extraction of steam distillates by solvents. The apparatus, depicted in Fig. 11,58, 7, may be employed for the continuous extraction of substances which are volatile in steam from their aqueous solutions or suspensions. Solvents of the ether type (i.e., lighter than water) or of the carbon tetrachloride type (i.e., heavier than water) may be used. A reflux condenser is inserted in the Bl9 socket, whilst flasks of suitable capacity are fltted into the lower B24 cone and the upper. B19 cone respectively. For extraction with ether, the flask attached to the upper. B19 cone contains the ether whilst the aqueous solution is placed in the flask fltted to the lower B2i cone the positions of the flasks are reversed  [c.224]

Endo-exo product mixtures were isolated using the following procedure. A solution of cyclopentadiene (concentration 2-10" M in water and 0.4 M in oiganic solvents) and the dienophile (concentration 1-5 mM) in the appropriate solvent, eventually containing a 0.01 M concentration of catalyst, was stirred at 25 C until the UV-absorption of the dienophile had disappeared. The reaction mixture (diluted with water in the case of the organic solvents) was extracted with ether. The ether layer was washed with water and dried over sodium sulfate. After the evaporation of the ether the  [c.67]

To a solution of 0.22 mol of butyllithium in about 150 ml of hexane were added 120 ml of dry THF with cooling below -10°C. The mixture was cooled to -70°C and 0.22 mol of tert.-butylallene (see Chapter VI, Exp. 2) was added in 10 min, while maintaining the temperature at about -70°C. After 30 min the solution of the lithiated allene was cooled to -100°C in a bath of liquid nitrogen. The cooling bath was then removed and 0.20 mol of trimethylchlorosilane was added with vigorous stirring in a few seconds. Fifteen minutes later the reaction mixture was poured into 200 ml of saturated ammonium chloride solution. After vigorous shaking the layers were separated and the aqueous layer was extracted with two 4Q-ml portions of diethyl ether. The combined solutions were dried over magnesium sulfate. After the greater part of the solvents had been distilled off at normal pressure through a 40-cm Vigreux column, the remaining liquid was distilled. The  [c.37]

Finally, a caveat. Despite its documented success in many situations, bioremediation may not always be able to meet current clean-up criteria for a particular site. Some standards are so tight that they are essentially "detection limit" standards, and it is not clear that biological processes will be able to remove contaminants to such low levels. For example, the level of contaminant may be so low that it does not induce the microorganisms to produce the enzymes necessary for biodegradation. Or perhaps the contaminant is bound to soil or sediment particles in such a way that it is not available for biodegradation, although it is stiU extractable with aggressive solvents in analytical procedures. These are areas that require further research, but bioremediation will be more likely to hilfill its promise as an important tool in contaminated site remediation if there is progress towards standards based on bioavailabihty and net environmental benefit from the clean up, rather than on arbitrary absolute standards.  [c.39]

The choice of separation method to be appHed to a particular system depends largely on the phase relations that can be developed by using various separative agents. Adsorption is usually considered to be a more complex operation than is the use of selective solvents in Hquid—Hquid extraction (see Extraction, liquid-liquid), extractive distillation, or azeotropic distillation (see Distillation, azeotropic and extractive). Consequentiy, adsorption is employed when it achieves higher selectivities than those obtained with solvents.  [c.291]

Solvent. Solvent choice is deterrnined by the chemical stmcture of the material to be extracted, and the rule that like dissolves like provides useful guidance. Thus vegetable oils (qv) consisting of triglycerides of fatty acids are normally extracted with hexane [110-54-3] whereas for free fatty acids, which are more polar than the triglycerides, more polar alcohols are used. Halogenated hydrocarbons and hexane are both widely used as solvents, and hquid carbon dioxide [124-38-9] (qv) appears to be suitable for extracting flavor components from plants (5) (see Supercritical fluids). Where a choice of solvent other than water exists on the grounds of comparable solubiUty of the solute, the following criteria are likely to be considered.  [c.88]

Hydrogen peroxide can also be recovered directly from the working solution by vacuum distUlation or by stripping with organic solvents. The organic solutions obtained by solvent stripping can be used to prepare peroxycarboxyHc acids or they can be extracted with water to obtain aqueous hydrogen peroxide of higher strength. The use of extract water containing sodium metaborate has been claimed to give sodium perborate, or that containing aHphatic carboxyHc acids to give peroxycarboxyHc acid. Other patents describe transfer of hydrogen peroxide from one solvent to another.  [c.476]

Latexes of synthetic resins are identified by ir spectrometry. Selective extraction with organic solvents is used to obtain purified fractions of the polymers for spectrometric identification. Polymeric films can be identified by the multiple internal reflectance ir technique, if the film is smooth enough to permit intimate contact with the reflectance plate. TAPPI and ASTM procedures have not been written for these instmmental methods, because the interpretation of spectra is not amenable to standardization.  [c.11]

Lanolin is wool grease that has been refined to lighten its color and reduce its odor and free fatty acid content. Wool wax is the pure Hpid material of the fleece, yellow to pale brown in color and extractable with the usual fat solvents such as diethyl ether and chloroform. Wool grease is a mixture of compounds that ate classed as waxes. However, it does not have the physical characteristics usually displayed by waxes. It is soft and slightly sticky, with a greasy appearance. Some centrifugaHy recovered greases are light buff or ivory in color and practically odorless. Those recovered by other methods contain  [c.353]

Food, Beverage, and Cooking Oil. Approximately 6% of the Hquid-phase activated carbon is used in food, beverage, and cooking oil production (74). Before being incorporated into edible products, vegetable oils and animal fats are refined to remove particulates, inorganics, and organic contaminants. Activated carbon is one of several agents used in food purification processes. In the production of alcoholic beverages, activated carbon removes haze-causing compounds from beer, taste and odor from vodka, and fusel oil from whiskey (82). The feed water for soft drink production is often treated with carbon to capture undesirable taste and odor compounds and to remove free chlorine remaining from disinfection treatment. Caffeine is removed from coffee beans by extraction with organic solvents, water, or supercritical carbon dioxide prior to roasting. Activated carbon is used to remove the caffeine from the recovered solvents (83).  [c.534]

Assessing whether a material is a copolymer or a mixture of homopolymers can sometimes be accomplished by extracting the prospective copolymers with solvents selective for the component homopolymers. However, this method is effective only when the copolymer segments differ significantly in solubiUty behavior. The situation is further compHcated by the fact that block copolymers can themselves act as compatibilizing agents for homopolymers and can confound extraction experiments. Alternatively, solution fractionation has been used to test copolymers versus homopolymers or polymer blends. Determining whether a co-polymer is block or random can often be made by nmr, nmr, or from T measurements (differential scanning calorimetry (dsc) or thermal-mechanical tests). However, detailed monomer unit sequence distributions are usually best determined by nmr. Using this technique, information on dyad (two monomer units) up to pentad (groups of five monomer units) can be obtained (99,100).  [c.187]

Oil from rape seed, coconut, com germ, sunflower seed, palm kernel, and oHves is traditionally produced by a combined process using pressing followed by extraction with organic solvents. CeU-waH degrading enzymes may be used to extract vegetable oil in an aqueous process. They break down the cell-wall stmcture and release the oil. This concept is already in commercial use in connection with oHve oil processing, and has been thoroughly investigated for rape seed oil extraction (95).  [c.303]

The theory of extraction with solvents has heen discussed in Section 1,22, and it has been shown that for a given volume of solvent several extractions with aliquot parts give better results than a single extraction with the total volume of the solvent. By way of illustration, the technique of the extraction of an aqueous solution with diethyl ether will be described. A separatory funnel (globular or pear-shaped with a short stem, see Figs. 11,1, 5, c and d) is selected of about twice the volume of the liquid to be extracted, and is mounted in a ring on a stand with a firm base. The barrel and plug of the stopcock are dried with a linen cloth, and lightly treated with a suitable lubricant (vaseline, etc. see third footnote in Section 11,38). A new well-fitting cork is selected for closing the mouth of the funnel alternatively, the ground glass stopper, supplied with the separatory funnel, may be used. The solution and the extraction solvent (usually about one third of the volume of the solution, but see Section 1,22) are introduced into the funnel, and the latter stoppered. All naked flames in the immediate vicinity should be extinguished. The funnel is then shaken gently (so that the excess vapour pressure f will be developed slowly), inverted, and the stopcock opened in order to relieve the excess pressure. The stopcock is again closed, the funnel again shaken, and the internal pressure released. When the atmosphere inside the funnel is saturated with ether vapour, further shaking develops little or no additional pressure. At this stage, the funnel is vigorously shaken for 2-3 minutes to ensure the maximum possible transfer of the organic substance to the ether layer, and then returned to the stand in order to allow the mixture to settle. When two sharply defined layers have formed, the lower aqueous layer is run oflF and separated as completely as possible. The residual ethereal layer is then poured out through the upper neck of the funnel contamination with any drops of the aqueous solution still remaining in the stem of the funnel is thus avoided. The aqueous solution may now be returned to the funnel and the extraction repeated, using fresh ether on each occasion until the extraction is complete. Not more than three extractions are usually required, but the exact number of extractions will naturally depend upon the partition coefficient (Section 1,22) of the substance between water and ether. The completeness of the extraction can always be determined by evaporating a portion of the last extract on the water bath and noting the amount of residue. The combined ethereal solutions are dried with an appropriate reagent (Section 11,39), and the ether removed on a water bath (Sections 11,5, 11,13 and 11,14). The residual organic compound is purified, depending upon its properties, by distillation or by recrystalliKition.  [c.150]

Acid Recovery. Approximately 4.0—4.5 kg of acetic acid per kg of cellulose acetate is used in the solution process ca 0.5 kg is consumed by the product and the remaining 3.5—4.0 kg is recovered as an aqueous solution of 25—35% acetic acid. This solution may also contain dissolved salts from sulfuric acid neutrali2ation, and dissolved and suspended low molecular weight cellulose and hemiceUulose acetates. Acetic acid is recovered from the clarified weak acid stream by solvent extraction with solvents such as ethyl acetate or methyl ethyl ketone. Ben2ene, also formerly used, is being phased out because of carcinogenic concerns. The organic extract is sent to a distillation column, and the aqueous raffinate phase, containing most of the inorganic salts, is discarded. The extraction solvent is distilled off, leaving glacial acetic acid. The energy requirements for acid recovery depend on the organic solvent used and may be in the 4.2—10.5 kj/g (1—2.5 kcal/g) range of acid recovered. A portion of the acetic acid may be subsequently converted to acetic anhydride by catalytic pyrolysis in good yield and at low cost. A new acetic anhydride process uses synthesis gas obtained from coal as feedstock (42,43).  [c.296]

We have found that in the system of presulfate initiator, the PVAc latexes are not dissolved transparently in the methanol-water mixture [8], and in the system of HPO initiator, the extraction of the polymer from the PVAc latex films with acetone greatly depends on the polymerization condition [9]. These results suggest that if a polymerization method can be found in which the grafting polymerization of VAc onto PVA is controlled to the minimum, a large portion of PVAc in the latex film will have a chance of extraction with solvents. In this Chapter, the preparations of the unique porous films from the PVAc latexes containing PVA as a protective colloid by an extraction of the PVAc particles with acetone and the characteristic properties of the porous films are summarized.  [c.167]

Place a mixture of 25 5 g. of n-valerio acid (Sections 111,83 and 111,84), 30 g. (37 -5 ml.) of dry n-propyl alcohol, 50 ml. of sodium-dried benzene and 10 g. (5-5 ml.) of concentrated sulphuric acid in a 250 ml. round-bottomed flask equipped with a vertical condenser, and reflux for 36 hours. Pour into 250 ml. of water and separate the upper layer. Extract the aqueous layer with ether, and add the extract to the benzene solution. Wash the combined extracts with saturated sodium bicarbonate solution until effervescence ceases, then with water, and dry with anhydrous magnesium sulphate. Remove the low boiling point solvents by distillation (use the apparatus of Fig. II, 13,4 but with a Claisen flask replacing the distilling flask) the temperature will rise abruptly and the fi-propyl n-valerate will pass over at 163-164°. The yield is 28 g.  [c.387]

It is useful to devote some conments to the following work-up procedure, which is often prescribed in the case of compounds, prepared in THF, that have a volatility comparable to that of THF (b.p. between 35 and 100 C at normal pressure). The problem is to remove the THF, the amount of which exceeds many-fold that of the product, and yet to isolate all of the volatile product which has been formed. The procedure to be followed consists in adding a high-boiling solvent (b.p. > 170 C at 760 mraHg) to the reaction mixture and subsequently extracting with water or, more efficiently, with dilute hydrochloric acid (if the compound is stable in acidic medium), until no more THF is present in the organic layer. As a rule this requires washing several times. The many aqueous layers obtained in this operation, may contain some of the product, but even this can be isolated by shaking the combined washings once or twice with the extraction solvent and subsequently removing the THF from these extracts by washing 5-6 times with water or dilute acid. It should be pointed out that the partition coefficient of the pmdacL between the extraction solvent and water (or the acid) must be large, but that of THF and the mentioned phases in the order indicated must be small. High-boiling ethers (e.g. diisoamyl ether) therefore seem unsuitable, and hydrocarbons (light petroleum fractions) are the solvents of choice. The further isolation procedure involves heating the dried extract in vacuo and condensing the vapour of the product in a strongly cooled receiver (see Fig. 5). The contents of the receiver always contain some extraction solvent and should therefore be redistilled, either at normal or under reduced pressure.  [c.2]

A solution of 0.21 mol of butyllithium in about 140 ml of hexane (note 1) was cooled below -40°C and 90 ml of dry THF ivere run in. Subsequently a cold (< -20 C) solution of 0.25 nol of propyne in 20 ml of dry THF was added with cooling below -20°C and a white precipitate was formed. A solution of 0.10 mol of anhydrous (note 2) lithium bromide in 30 ml of THF was added, followed by 0.20 mol of freshly distilled cyclopentanone or cyclohexanone, all at -30°C. The precipitate had disappeared almost completely after 20 min. The cooling bath was then removed and when the temperature had reached 0°C, the mixture was hydrolyzed by addition of 100 ml of a solution of 20 g of NHi,Cl in water. After shaking and separation of the layers four extractions with diethyl ether were carried out. The extracts were dried over magnesium sulfate and the solvents removed by evaporation in a water--pump vacuum. Careful distillation of the remaining liquids afforded the following  [c.75]

A solution of 0.20 mol of butyllithium in about 140 ml of hexane was cooled below -30°C. Dry tetrahydrofuran (100 ml) was added with efficient cooling. Subsequently 0.22 mol of the alkyne ( propyne and butyne were dissolved in 30 ml of THF, cooled below -2o c) was introduced in 2 min and with vigorous stirring. During this addition the temperature was kept below -10°C. Subsequently the ketone (0.20 mol) was added in 10 min with cooling between -30 and -50°C. In the cases of the reactions of CH3CeCLi and CH30CH2C5CLi with cyclopentanone and cyclohexanone, however, a solution of 0.10 mol of anhydrous lithium bromide (freed from traces of water by heating the commercial salt at 150-170°C during 30 min in a water-pump vacuum) in 20 ml of THF was added first (note 1). After the addition of the ketones the cooling bath was removed and the temperature of the mixture was allowed to rise to -5°C. Methyl iodide or ethyl iodide (0.28 mol) and dry DMSO (note 2) (160 ml) were added successively. The temperature of the mixture rose to OO-OS C and salt separated from the solution. The reaction was terminated by warming the mixture for 1.5 h at qB-BO C. Two clear layers were formed when stirring was stopped. Ice-water (500 ml) was added and after separation of the layers four extractions with redistilled pentane were carried out. The combined solutions were washed three times with brine and were subsequently dried over magnesium sulfate. After filtration and removing the solvents in a water-pump vacuum the residue was carefully distilled through a 30-cm-Widmer column. The following compounds were prepared (yields at least 80S)  [c.231]

Pollution Prevention. Procedures haven been developed for recovery of composite ammonium perchlorate propellant from rocket motors, and the treatment of scrap and recovered propellant to reclaim ingredients. These include the use of high pressure water jets or compounds such as ammonia, which form fluids under pressure at elevated temperature, to remove the propellant from the motor, extraction of the ammonium perchlorate with solvents such as water or ammonia as a critical fluid, recrystalli2ation of the perchlorate and reuse in composite propellant or in slurry explosives or conversion to perchloric acid (166,167).  [c.50]

In the Ahied process two solvents ate used. The first has low volatihty and is designed to be an effective solvent for the high molecular weight FAN. The resultant solution or xetogel is extmded with a jet stretch of lOx or less through an ak gap into a cooling bath where the extmdate is converted into gel fibers. Gelation is important because it restricts chain mobhity and prevents chain entanglements from forming as the solvent is extracted. The first solvent is extracted with a volatile solvent, and the solvent is then removed by evaporation. The fibers are drawn in several stages starting with the usual jet stretch at the spinneret face. Subsequent drawing is done after the solvent is removed in stages of increasing temperature from 130 to 230°C. Typical wet spinning solvents ate used for solvent 1 and water is used as solvent 2. The AUied and DSM processes ate similar, but DSM adds zinc chloride to the spinning solution to prevent phase separation and aid in drawing. The total draw ratio may be anywhere from 8-29x, with the highest tenacities achieved at the highest draw ratios. Table 3 compares the properties of gel spun FAN with other high performance fibers (qv) (71,72).  [c.284]

Natural Products. Various methods have been and continue to be employed to obtain useful materials from various parts of plants. Essences from plants are obtained by distillation (often with steam), direct expression (pressing), collection of exudates, enfleurage (extraction with fats or oils), and solvent extraction. Solvents used include typical chemical solvents such as alcohols and hydrocarbons. Liquid (supercritical) carbon dioxide has come into commercial use in the 1990s as an extractant to produce perfume materials. The principal forms of natural perfume ingredients are defined as follows the methods used to prepare them are described in somewhat general terms because they vary for each product and suppHer. This is a part of the industry that is governed as much by art as by science.  [c.76]

In the wood rosin process, rosin is isolated from aged pine stumps that have been left in fields cleared for farming or lumbering operations. The stumps are cut and shredded to pieces the size of matchsticks. The wood chips are then extracted with an appropriate solvent, eg, aUphatic or aromatic petroleum hydrocarbons or ketones. The extract is fractionally separated into nonvolatile cmde rosin, volatile extractibles, and recovered solvent. The dark rosin is usually refined further to lighter-colored products using selective solvents or absorption.  [c.138]

A number of techniques have been developed for the trace analysis of siUcones in environmental samples. In these analyses, care must be taken to avoid contamination of the samples because of the ubiquitous presence of siUcones, particularly in a laboratory environment. Depending on the method of detection, interference from inorganic siUcate can also be problematic, hence nonsiUca-based vessels are often used in these deterrninations. SiUcones have been extracted from environmental samples with solvents such as hexane, diethyl ether, methyl isobutylketone, ethyl acetate, and tetrahydrofuran (THF)  [c.59]

Vanillin [121 -33-5] a natural product, can be found as a glucoside (glucovanillin) in vanilla beans, at concentrations of about 2%. It can be extracted with water, alcohol, or other organic solvents. Approximately 250 by-products have been identified in natural vanilla, out of which 26 are present at levels in excess of 1 ppm. The balance of aU. these products contributes to the subde taste of vanilla beans. The vanilla bean contains about 2% vanillin, but the 10% extract prepared from beans has several times the strength of a solution of 2% vanillin. For this reason, the U.S. Food and Dmg Administration (FDA) regulations state that one part of vanilla beans is equivalent to 0.07 parts vanillin in flavor strength. The best known natural source of vanillin is the vanilla plant. Vanillaplanifolia A., which belongs to the orchid family. It is cultivated mainly in Mexico, Madagascar, Reunion, Java, and Tahiti.  [c.396]

Pesticides. Chlorinated hydrocarbon insecticides are deterrnined with an electron-capture detector foUowing extraction with an organic solvent (20). If polychlorinated biphenyls (PCBs) are known to be present or if the extract contains so many pesticides that separation by glc is difficult, the extract should be passed through a Florisd column. Elution of the column with different solvents allows certain group separations of the pesticides. The foUowing organochlorinated pesticides and PCBs have been deterrnined by the method lindane, heptachlor, heptachlor epoxide, aldrin, dieldrin, Aj -l,l-dichloro-2,2-bis( -chlorophenyl)ethane (, j ) -TDE),N / lTT tfichloro-2,2-bis( -chlorophenyl)ethane o,p  [c.233]

Lipids. The hpids of the fiber are beheved to be constituents of the ceU membranes (see Fibers). Together with interceUular material they constitute about 1% of the fiber but play an important role in many properties, such as the interceUular diffusion of reagents. The free hpids are extractable with organic solvents and consist of fatty acids, sterols, and trace amounts of glycerides, sphinohpids, and glycohpids (44). Although phosphohpid is present in the wool foUicle membranes, only trace amounts of phosphohpid are found in the keratinized fiber (45,46). Cholesterol and its biosynthetic precursor desmosterol are the main sterol components of the free hpids. In addition to the free hpids, wool contains some hpids that are assumed to be covalendy bound to proteins. These components are not readily removed by organic solvents but can be released by mild alkaline hydrolysis. Covalently bound surface hpids account for the hydrophobicity of the fiber surface. An unusual odd-chain fatty acid, 18-methyleicosanoic acid, is the predominant fatty acid, accounting for approximately 60% of the bound fatty acid on the surface of wool.  [c.343]

A widely used colorimetric method for the estimation of microgram quantities of antimony is based on the reaction of antimony(V) with rhodamine B [81-88-9] C2gH22ClN202, in hydrochloric acid solution to form a colored complex that is extracted with organic solvents and measured spectrophotometricaHy (10). For the deterrnination of antimony in trace amounts, methods employing neutron activation or atomic absorption have been widely used. A comparison of the two methods has been reported (11). Both methods gave satisfactory results when used to determine specified values of antimony in several different biological materials. An excellent description of the deterrnination of antimony involving the generation of stibine by sodium borohydride, followed by atomic absorption analysis, has also been reported (12).  [c.201]

Ghlorohydrination with Nonaqueous Hypochlorous Acid. Because the presence of chloride ions has been shown to promote the formation of the dichloro by-product, it is desirable to perform the chlorohydrination in the absence of chloride ion. For this reason, methods have been reported to produce hypochlorous acid solutions free of chloride ions. A patented method (48) involves the extraction of hypochlorous acid with solvents such as methyl ethyl ketone [78-93-3J, acetonitrile, and ethyl acetate [141-78-6J. In one example hypochlorous acid was extracted from an aqueous brine with methyl ethyl ketone in a 98.9% yield based on the chlorine used. However, when propylene reacted with a 1 Af solution of hypochlorous acid in either methyl ethyl ketone or ethyl acetate, chlorohydrin yields of only 60—70% were obtained (10).  [c.74]


See pages that mention the term Extraction with solvents : [c.481]    [c.189]    [c.378]    [c.37]    [c.319]    [c.37]    [c.221]    [c.21]    [c.42]    [c.90]    [c.171]    [c.236]   
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Textbook on organic chemistry  -> Extraction with solvents