Extraction with basic methanol, separation

Table V. Separation of Preasphaltenes by Extraction with Basic Methanol...

This is my version, but may be better done. First one, evaporate methanol, better with vacuum. Then we have two layers similar in volume, we add 100 of solvent and 50 cc of basic solution (sodium carbonate, bicarbonate or 10 % NaOH ). We shake it and may be we will have little more precipitate or tar. Also may be we can t see separation, then w/e add a bit more solvent without shaking to see separation. We make two more extractions with 50 cc of solvent. Even if we can t see separation, we can add enough HCI and shake, this will forme some tar and layers will be distincts, so we can separate and make a basic wash. Sometimes I ve done first an acid wash, but I can t sure it s better. I m thinking now may be is better to do all extraction as Strike s top 3. Add acid solution, like 250 cc (less PdClz and no CuCI) 15% HCI, extract and make a basic wash. 

A total of 3 g (0.13 moles) of sodium hydride is added to a solution consisting of 10 g of 17 -hydroxy-5a-androstan-3-one (36 mmoles) in 200 ml of benzene and 10 ml of ethyl formate. The reaction mixture is allowed to stand under nitrogen for 3 days followed by dropwise addition of 10 ml of methanol to decompose the excess of sodium hydride. The solution is then diluted with 300 ml water and the layers are separated. The basic aqueous solution is extracted with ether to remove neutral material. The aqueous layer is acidified with 80 ml of 3 A hydrochloric acid and the hydroxymethylene steroid is extracted with benzene and ether. The combined organic extracts are washed with water and saturated sodium chloride solution and then dried over magnesium sulfate and concentrated. The residue, a reddish-yellow oil, crystallized from 10 ml of ether to yield 9.12 g (83%) of 17 -hydroxy-2-hydroxymethylene-5a-androstan-3-one mp 162-162.5°. Recrystallization from chloroform-ether gives an analytical sample mp 165-165.5° [a]o 53° (ethanol) 2 ° 252 mjj. (g 11,500), 307 m u (e 5,800). 

Acetochlor and its metabolites are extracted from plant and animal materials with aqueous acetonitrile. After filtration and evaporation of the solvent, the extracted residue is hydrolyzed with base, and the hydrolysis products, EMA and HEMA (Figure 1), are steam distilled into dilute acid. The distillate is adjusted to a basic pH, and EMA and HEMA are extracted with dichloromethane. EMA and HEMA are partitioned into aqueous-methanolic HCl solution. Following separation from dichloromethane, additional methanol is added, and HEMA is converted to methylated HEMA (MEMA) over 12 h. The pH of the sample solution is adjusted to the range of the HPLC mobile phase, and EMA and MEMA are separated by reversed phase HPLC and quantitated using electrochemical detection. 

Another Hydrogenation with Platinum Oxide. JACS, 55, 2694. This method is used to reduce those hydrox-mandelonitriles in the amphetamine section. It uses low pressure and can be used on about any reducible compound. It can also use palladium oxide as the catalyst. A solution of 35.8 g of phenyl-2-propanol in 250 ml of 80% ethanol containing 7.3 g of HCl is hydrogenated for 3 hours in a Parr hydrogenation bottle at 3,5kg/cm or 50 p.s.i, over 0,5 g of platinum oxide (or palladium oxide Raney nickel may also work) or an equimolar ratio of analog catalyst for about 3 hours. Filter off the catalyst and rinse with a little water to wash all the product from the catalyst. Dilute the filtrate to 1 liter of volume with water and extract twice with ether to remove any acid insoluble material. The ether extracts do not contain product. The aqueous layer is made alkaline with solid NaHCOs to a pH of 8-9 and the basic oil which separates is extracted with two 300 ml portions of ether. This ether solution is dried over MgS04, and filtered, then evaporated to remove the ether. To convert to the oxalate, add ether to the crude product and add to a solution of 9.6 g of oxalic acid dihydrate in a small volume of methanol. Give ample... 

Shaker table techniques have been developed with increased efficiency for acidic and basic compounds. The sample is placed in an extraction vessel (Erlenmeyer flask or glass jar) together with an extracting solvent, dichloromethane methanol H2SO4 (70 29 1) for acidic compounds or dichloromethane methanol NaOH (70 29 1) for basic compounds. The vessel is placed on a platform shaker for 1 h and then the liquid is decanted into a separatory funnel-containing water. The separatory funnel is gendy shaken, the layers are allowed to separate as for a normal liquid liquid extraction, and the solvent is collected for further processing. 

Vacuum-still bottoms from the H-coal liquefaction process were separated into acid, neutral, and basic fractions by precipitation with acids or by extraction with bases. About one-third of the preasphaltene and one-sixth of the asphaltene fraction were precipitated by acids equivalent weights of the bases were in the range 1200-1800 for preasphaltenes and 600-800 for asphaltenes. The acidic components were obtained either by extraction with aqueous sodium hydroxide or by extraction with benzyltrimethylammonium hydroxide in methanol. About one-fifth of the asphaltene and one-fourth of the presasphaltene fractions were obtained as acids, and up to 10% as amphoteric substances. Nitrogen and sulfur were present in all fractions found. Deno axidation (CF3C02H, H202, H 04) gave dicarboxylic acids from malonic to adipic in addition to mono acids. 

At-Methylenebenzylamine (11.9g, 0.09 mol) is added dropwise to a solution of biacetyl monoxime (10.1 g, 0.12 mol) in glacial acetic acid, and the solution is allowed to stand (12 h). After saturation with dry HCl and pouring into diethyl ether the semi-solid which separates is wa.shed with ether, taken up in methanol, and reprecipitated as a fine, white solid (12.7g, 53%) by addition of ether. The hydrochloride is made basic with ammonia (d. 0.88) and extracted with chloroform. The organic extracts are dried (MgS04), the solvent is removed, and the solid product recrystallized from acetone, to... 

A mixture consisting of 254 parts of 2-nitro-l-phenyl-1-propanol. 600 parts of methanol, 90 parts of acetic acid, and 7 parts of Raney nickel catalyst, was reduced with molecular hydrogen under conditions similar to those set forth in Example 1. At the conclusion of the reduction, the charge was removed from the hydrogenation apparatus, and filtered. The filtrate was then distilled at atmospheric pressure up to a temperature of 80° C. to remove the methanol present. The still residue was next extracted with a 100-part portion of a 50-50 mixture of benzene butanol, in order to remove non-basic impurities from the crude reduction product. After considerable agitation, the resulting mixture was allowed, to settle, and the upper benzene-butanol layer discarded. To the aqueous solution of the phenyl amino propanol acetate (salt) was added 60 parts of sodium hydroxide in the form of a 50 percent solution. This treatment resulted in the formation of two separate layers. The upper layer, containing principally free phenyl amino propanol, was separated and distilled under reduced pressure (60-70 mm.) up to a temperature of 100° C. At this point the pressure was further reduced (1-2 mm), and substantially pure phenyl amino propanol was collected at 125° C. 

In situations when analysis is required to establish the presence and identity of calystegines in a plant extract it is not necessary to utilize a complex series of chromatographic separations. The plant material can be extracted with methanol or methanol-water and passage over a Dowex 50W-X8 column with dilute ammonium hydroxide as eluant provides substantial purification, yielding the alkaloid fraction, including other polyhydroxy alkaloids, contaminated only by basic amino adds. The extract can thus be rapidly prepared for analysis [29,30]. 

Extraction and work-up. Of the standard methods of alkaloid extraction, percolation with methanol has been especially favoured by Australian workers, followed by removal of the solvent and dilute acid extraction. Besides alkaloids, methanol dissolves large amounts of other plant constituents which hamper the acid extraction. One strategy used to overcome this was to completely dissolve the residue left after removal of the methanol in a minimal quantity of warm glacial acetic acid, an excellent solvent for most plant constituents. The solution was then diluted with water until no more precipitate formed if the evaporation of the methanol had been carried out in a pilot plant-scale rotary evaporator, the whole operation could be done in the same slowly rotating vessel. After separation of the precipitate, most of the dilute acid could be removed in vacuo in the same equipment to give an aqueous solution of crude alkaloid acetates largely free from non-basic materials 70). 

Tuber slices (338 kg) (1.5-2,0 mm thickness) of Ri cultivar Rishiri were inoculated with a zoospore suspension (250000-500000 zoospores/ml) of incompatible race of Phytophthora infestans (Mont.) de Bary, race 0 and incubated at 18-20°C for two days. The inoculated slices were stored in an ice-box (-30°C) for a week and then immersed in methanol (250 1) for a week. The supernatant was separated by decantation and the process was repeated twice with methanol (2 x 150 ml). The methanol extracts were combined and concentrated under reduced pressure below 30°C. The concentrate was extracted with chloroform and evaporated to yield oily residue from which a solid material was precipitated on treatment with acetone and was then removed by filtration. The filtrate w as c oncentrated to yield an o ily residue which w as treated with hexane. The hexane solution was concentrated, extracted with ether and washed with aqueous sodium carbonate (10%) and hydrochloric acid (0.1 M) to remove acidic and basic components. The ether extract was washed with water, dried and evaporated. The residue, which contained many c ompounds (by tlc) w as subjected toehromatographic p urification over silicic acid (Mallinckrodt, AR-100) and celite. Benzene ether (1 1 and 1 2) afforded crude rishitin which showed an almost single spot on tic. This was chromatographed over silica gel (Merck). Ether eluted pure rishitin (40) (3.9 g, from 338 Kg tuber slices), m.p. 65-67°C, [ai]-35.1°, max s, 3060,1640 and 890 cm 1 1HNMR 51.12 (3H, d, J=6 Hz), 3.12 (1H, t, J=9Hz),3.55 (lH,br,do,d, J=9and7 Hz), 4.18 (2H, br, s, 2 OH) C,3NMR 148.9 (Cn), 129.0 (C5), 124.9 (C10), 10.9 (C12), 79.2 (C8), 71.5 (C2), 41.6 (C7), 40.4 (C4), 38.3 (C8), 31.1 (C6), 29.7 (C9), 26.5 (C,), 21.0 (C13), 16.4 (Cm).22... 

Methyl formate and propylene oxide have close boiling poiats, making separation by distillation difficult. Methyl formate is removed from propylene oxide by hydrolysis with an aqueous base and glycerol, followed by phase separation and distillation (152,153). Methyl formate may be hydrolyzed to methanol and formic acid by contacting the propylene oxide stream with a basic ion-exchange resia. Methanol and formic acid are removed by extractive distillation (154). 

The isolation of flavonoids from the methanol extract of G. uralensis was carried out under non-basic conditions, because some flavonoids isomerize under basic conditions, e.g. racemization of flavanones and isoflavanones, ring-open reaction of flavanones etc. Bioactive fractions were separated by some chromatographic methods and each step was monitored with anti-H. pylori activity with the paper disk method. Eighteen compounds were isolated from these bioactive fractions and... 

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