Solvent purification methanol

The residue is triturated with methanol to afford a crystalline solid. This material contains no detectable amount of starting material by paperstrip chromatography but shows two UV absorbing spots near the solvent front (methanol-formamide 2 1 vs benzene-n-hexane 1 1). An aliquot is recrystallized three times from a mixture of benzene and n-hexane to give 17a,20,20,21-bis(methylenedioxy)-11(3-hydroxy-6,16a-dimethyl-4,6-pregnadiene-3-one which is used in the subsequent step of the synthesis without further purification. 

General Considerations. The following chemicals were commercially available and used as received 3,3,3-Triphenylpropionic acid (Acros), 1.0 M LiAlH4 in tetrahydrofuran (THF) (Aldrich), pyridinium dichromate (Acros), 2,6 di-tert-butylpyridine (Acros), dichlorodimethylsilane (Acros), tetraethyl orthosilicate (Aldrich), 3-aminopropyltrimethoxy silane (Aldrich), hexamethyldisilazane (Aldrich), tetrakis (diethylamino) titanium (Aldrich), trimethyl silyl chloride (Aldrich), terephthaloyl chloride (Acros), anhydrous toluene (Acros), and n-butyllithium in hexanes (Aldrich). Anhydrous ether, anhydrous THF, anhydrous dichloromethane, and anhydrous hexanes were obtained from a packed bed solvent purification system utilizing columns of copper oxide catalyst and alumina (ether, hexanes) or dual alumina columns (tetrahydrofuran, dichloromethane) (9). Tetramethylcyclopentadiene (Aldrich) was distilled over sodium metal prior to use. p-Aminophenyltrimethoxysilane (Gelest) was purified by recrystallization from methanol. Anhydrous methanol (Acros) was... 

A smaller scale and less efficient synthesis of the phenyl derivative of 1 has been reported. The method described for the title compound 1 provides excellent synthetic access to the p-chlorophenyl-substituted thiazolethione 1. It offers higher yields in every step of the synthesis, reduces the amount of hydroxylamine hydrochloride used in Step A to a third and avoids the use of halogenated solvents and methanol. Further, only one purification step is necessary at the very end of the synthesis to afford pure thione 1. The protocol for N-hydroxy-4-(p-chlorophenyl) thiazole-2(3H)-thione has also been applied to syntheses of the respective p-substituted phenyl derivatives 7-9 from the respective acetophenones (Figure 2)... 

After extraction of alkaloids from powdered hyoscyamus (4 g) and purification, an aliquot is applied to 0.5 mm layers of silica gel G which developed for 1 hour with the solvent ahydrous methanol-aqueous ammonia (200 1). After development, the plates are dried at room temperature, sprayed with modified... 

The membranes used for ethanol purification are also suitable for dehydration of many other organic solvents, including methanol, isopropanol, butanol, methyl ethyl ketone, acetone, and chlorinated solvents. Commercial units use up to 12 stages with reheating between stages, and product water contents lower than 100 ppm can be obtained. 

For preparative purposes, purifications based on the precipitation of alkaloids are sometimes employed. A crude extract of the alkaloids is made with aqueous acid, subsequently the alkaloids are precipitated with reagents such as Mayer s reagent (IM mercury chloride in potassium iodide) or Reinecke s salt (5% ammonium reineckate in 30% acetic acid) at pH 2, or picric acid (saturated aqueous solution) at pH 5-6. After collection of the precipitate by filtration or centrifugation, the precipitate is dissolved in an organic solvent (acetone-methanol-water 6 2 1). The complexing group is then removed by means of an anion exchanger (Jordan and Scheuer 1965 Verpoorte and Baerheim Svendsen 1976). This method is particularly suited for the purification of quaternary alkaloids. 

Even smaller, nanometer size particles, can be prepared Irom cyclodextrin. These particles are useful as a carrier for pharmaceuticals and cosmetics. First, a solution of cyclodextrin in an organic solvent mixture is prepared, followed by the preparation of a water dispersion of surfactant. When the two components are mixed together a colloidal dispersion of microspheres is produced. Particles sizes range Irom 90 to 900 nm. Typical solvents are methanol, ethanol, isopropanol, and acetone. Solvents are used in the purification of xanthan gum to lower ash and to obtain a product with no traces of solvents. Lower alcohol is used as the solvent. Solvents have also been used to decolor fatty acid esters. Crude oils extracted by pressing or with solvents cannot be used in cosmetic products. Re-... 

Table 2 summarizes the results for solvent purification by frontal analysis. In each case, purification improves their absorbance at the 1 cut-off point (AA). The small improvement in the case of ITPLC-grade methanol B is expected for this high-purity... 

Characteristics of applied initiators (potassium persulphate (PP), benzoyl peroxide (BP), 2,2 -azobisisobutyronitrile (AIBN)) and solvents (DMSO, methanol, aeetone, ehloroform) conformed to the reference data after purification by conventional methods. 

Previous research in this project dealt mainly with soxhlet extraction in general and related work as purification of solvents and extracts, testing several solvents in terms of extraction power to PAH, stability at boiling point and selectivity. Previously used solvents were methanol, dichloro-methane, trichloromethane, tetrachloromethane, cyclohexane, benzene, toluene, all xylenes, mesitylene, tetralin, tetrahydrofuran and acetic acid. 

The purification procedure of choice is vacuum distillation. Additionally, the melting point of 10.5°C allows a very efficient low temperature recrystallization from solvents like methanol, ethanol or mixtures thereof. ... 

Isolation is performed after defatting by solvent extraction (methanol, ethanol, their aqueous mixtures or slightly acidified water), distribution of the crude extract between water and an immiscible solvent phase, and precipitation of s. from the latter. Further concentration and purification may be achieved by chromatographic techniques. 

Reversed-phase chromatography is widely used as an analytical tool for protein chromatography, but it is not as commonly found on a process scale for protein purification because the solvents which make up the mobile phase, ie, acetonitrile, isopropanol, methanol, and ethanol, reversibly or irreversibly denature proteins. Hydrophobic interaction chromatography appears to be the least common process chromatography tool, possibly owing to the relatively high costs of the salts used to make up the mobile phases. 

Fiaal purification of propylene oxide is accompHshed by a series of conventional and extractive distillations. Impurities ia the cmde product iaclude water, methyl formate, acetone, methanol, formaldehyde, acetaldehyde, propionaldehyde, and some heavier hydrocarbons. Conventional distillation ia one or two columns separates some of the lower boiling components overhead, while taking some of the higher boilers out the bottom of the column. The reduced level of impurities are then extractively distilled ia one or more columns to provide a purified propylene oxide product. The solvent used for extractive distillation is distilled ia a conventional column to remove the impurities and then recycled (155,156). A variety of extractive solvents have been demonstrated to be effective ia purifyiag propylene oxide, as shown ia Table 4. 

Polyethers are usually found in both the filtrate and the mycelial fraction, but in high yielding fermentations they are mosdy in the mycelium because of their low water-solubiUty (162). The high lipophilicity of both the free acid and the salt forms of the polyether antibiotics lends these compounds to efficient organic solvent extraction and chromatography (qv) on adsorbents such as siUca gel and alumina. Many of the production procedures utilize the separation of the mycelium followed by extraction using solvents such as methanol or acetone. A number of the polyethers can be readily crystallized, either as the free acid or as the sodium or potassium salt, after only minimal purification. 

The purification of the COG involves washing the sour COG, Ri, with sufficient aqueous ammonia and/or chilled methanol to absorb the required amounts of hydrogen sulfide. The acid gases are subsequently stripped from the solvents and the regenerated... 

The reaction mixture is diluted with 250 ml of water, the mixture is transferred to a 2 liter flask using methanol as a wash liquid, and the organic solvents are distilled at 20-25 mm using a rotary vacuum evaporator. The product separates as a solid and distillation is continued until most of the residual toluene has been removed. The solid is collected on a 90 cm, medium porosity, fritted glass Buchner funnel and washed well with cold water. After the material has been sucked dry, it is covered with a little cold methanol, the mixture is stirred to break up lumps, and the slurry is kept for 5 min. The vacuum is reapplied, the solid is rinsed with a little methanol followed by ether, and the material is air-dried to give 9.1 g (85%), mp 207-213° after sintering at ca. 198°. Reported mp 212-213°. The crude material contains 1.0-1.5% of unreduced starting material as shown by the UV spectrum. Further purification may be effected by crystallization from methanol. 

A solution of the acylated thiocyanatohydrin in a minimal amount of 5% potassium hydroxide in diglyme (other solvents such as methanol, ethanol or tetrahydrofuran have also been used) is stirred for 2 days at room temperature. Water is added to the reaction mixture to precipitate the product which is filtered or extracted with ether (or chloroform). The ether extract is washed several times with water, dried (Na2S04), and concentrated under vacuum. The thiirane usually can be crystallized from an appropriate solvent pair. Chromatography over alumina has been used for the purification of episulfides. 

The ionic clusters observed are not limited to aqueous electrolyte solutions only. In fact very similar results were obtained for methanolic solutions as well [25]. This shows that sufficiently large and stable ionic clusters are a fairly common occurrence whenever ions are dissolved in polar solvents. The clusters are an essential factor in the facilitation of reverse osmosis purification. Since many industrially important solutions include ions in polar solvents, it is important to account for them in separation involving such solvents. 

A mixture of 50 g of betamethasone, 50 cc of dimethylformamide, 50 cc of methyl orthobenzoate and 1.5 g of p-toluenesulfonicacid Is heated for 24 hours on oil bath at 105°C while a slow stream of nitrogen is passed through the mixture and the methanol produced as a byproduct of the reaction is distilled off. After addition of 2 cc of pyridine to neutralize the acid catalyst the solvent and the excess of methyl orthobenzoate are almost completely eliminated under vacuum at moderate temperature. The residue Is chromatographed on a column of 1,500 g of neutral aluminum oxide. By elution with ether-petroleum ether 30 g of a crystalline mixture are obtained consisting of the epimeric mixture of 170 ,21 -methyl orthobenzoates. This mixture is dissolved without further purification, in 600 cc of methanol and 240 cc of methanol and 240 cc of aqueous 2 N oxalic acid are added to the solution. The reaction mixture is heated at 40°-50°C on water bath, then concentrated under vacuum. The residue, crystallized from acetone-ether, gives betamethasone 17-benzoate, MP 225°-231°C. 

The crude product separates as a solid from the reaction medium and is recovered by filtration, and it is then washed thoroughly with ether and dissolved in 350 ml 1 N HCI. Then, approximately 250 ml of the aqueous solvent is removed with a rotary evaporator and the evaporation residue combined with 125 ml methanol and filtered through decolorizing charcoal. The product is precipitated as the HCI salt by the addition of 7 parts of acetone. The resulting crystalline material is removed by filtration dried at 40°C with vacuum, and has a melting point of about 242°C and Is used without further purification. 

Purification of luciferin (Rudie etal., 1976). The luciferin fractions from the DEAE-cellulose chromatography of luciferase were combined and concentrated in a freeze-dryer. The concentrated solution was saturated with ammonium sulfate, and extracted with methyl acetate. The methyl acetate layer was dried with anhydrous sodium sulfate, concentrated to a small volume, then applied on a column of silica gel (2 x 18 cm). The luciferin adsorbed on the column was eluted with methyl acetate. Peak fractions of luciferin were combined, flash evaporated, and the residue was extracted with methanol. The methanol extract was concentrated (1 ml), then chromatographed on a column of SephadexLH-20 (2 x 80 cm) usingmethanol asthe solvent. The luciferin fractions eluted were combined and flash evaporated. The residue was... 

Purification of the activation products (PMs). The methylamine activation product dissolved in methanol is purified by chromatography, first on a column of silica gel using a mixed solvent of chloroform/ethanol, followed by reversed-phase HPLC on a column of divinylbenzene resin (such as Jordi Reversed-Phase and Hamilton PRP-1) using various solvent systems suitable for the target substance (for example, acetonitrile/water containing 0.15% acetic acid). 

While water has been used as a solvent more than any other media, nonaqueous solvents [e.g., acetonitrile, propylene carbonate, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or methanol] have also frequently been used. Mixed solvents may also be considered for certain applications. Double-distilled water is adequate for most work in aqueous media. Triple-distilled water is often required when trace (stripping) analysis is concerned. Organic solvents often require drying or purification procedures. These and other solvent-related considerations have been reviewed by Mann (3). 

The alkanephosphonic acid dichlorides obtained by these methods are converted with amines, with all reactions carried out in solvents such as acetone, benzene, or diethyl ether at 10°C with triethylamine as HC1 captor. The conversion runs quantitatively followed by a purification with the help of column chromatography with chloroform/methanol in a ratio of 9 1 as mobile phase. The alkanephosphonic acid bisdiethanolamides could be obtained as pure substances with alkane residues of C8, C10, C12, and Ci4. The N-(2-hydroxyethane) alkanephosphonic acid 0,0-diethanolamide esters were also prepared in high purity. The obtained surfactants are generally stable up to 100°C. Only the alkanephosphonic acid bismonomethylamides are decomposed beneath this temperature forming cyclic compounds. 

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