Methanol, removal

In a modification of this scheme, hydroxypregnenolone is first acetylated under mild conditions to the 3-acetate and then under forcing conditions with caproic anhydride to give the acetate-caproate (122). Ester interchange with methanol removes the acetate at 3 Oppenauer oxidation affords hydroxyprogesterone caproate (124). ... 

Preparation of 9, 11 -Epoxy-17a-21 -Dihydroxy-16 -Methyl-4-Pregnene-3 0-Dione 21-Acetate To a stirred solution of 100 mg of the 9a-bromo-11(3,17a,2Ttrihydroxy-16 3-methyl-4-pregnene-3,20-dione 21-acetate in 3 ml of tetrahydrofuran and 1 ml of methanol under nitrogen was added 1.02 ml of 0.215 N methanolic sodium methoxide. After 10 minutes at 25°C, 0.2 ml of acetic acid was added and the methanol removed in vacuo. The residue was acetylated with 1.00 ml of pyridine and 0.5 ml of acetic anhydride at 60°C for 70 minutes. The mixture was taken to dryness in vacuo, water added, and the product extracted into chloroform. The residue was crystallized from ether-acetone to give pure 9(3,11 (3-epoxy-17a,21-dihydroxy-16(3-methyl-4-pregnene-3,20-dione 21-acetate. 

Unisol process. In this process, mixture of caustic soda and methanol removes mercaptans from gasoline. 

Column side-draws, methanol removal from, 18 520... 

The soil samples are air dried. Transfer 50g into a 500ml flat-bottomed flask and extracted with methanol. Remove the methanol by using a rotary evaporator with a water bath at 55°C. Cool the flask and add 5.0ml of methanol, swirl to dissolve the residue and filter the solution through a Whatman No. 42 filter-paper. Using a flow-rate of 0.6ml min-1, inject 5pl of extract into the liquid chromatograph. Calculate the uron content of the sample by comparing the peak height obtained with those obtained from 5pl injections of standard solutions. 

To a vigorously stirred solution of 1,2-diaminoethane (107 g, 118 ml, 1.781 mol) in methanol (150 ml), at 0°C under nitrogen, was added a solution of (G = 1.5) dentin -PAMAM(C02Me)16 [5] (10 g, 0.004 mol) in methanol (30 ml). The addition was controlled such that the temperature did not rise above 40 °C. The mixture was stirred at room temperature for 96 h, after which time no ester groups were detectable by NMR spectroscopy. The methanol was removed by vacuum distillation at < 40°C, and the excess 1,2-diaminoethane was removed by azeotropic distillation using a mixture of toluene and methanol (9 1). The remaining toluene was removed by azeotropic distillation with methanol and finally the methanol removed under vacuum (10 1 mm Hg, 50°C, 48 h) to give the amine terminated G = 2.0 dendrimer as a pale yellow oil (10.9 g, 94%). 

The use of o-dichlorobenzene as a solvent is recommended. If the reaction is carried out in excess dimethylformamide alone, the product is contaminated with unreacted anthracene. It is then best to extract the crude material with cold methanol, remove the anthracene by filtration and recover the product by dilution with water. 

Acetone has been used as the organic solvent but can cause problems due to the formation of acetonides with vicinal diols in slightly acid conditions (lU,15). After the aqueous methanol extraction, the homogenate is filtered and the methanol removed from the filtrate under reduced pressure at 1+0° or below. At this stage it is common to buffer the aqueous residue, usually with potassium phosphate. With some tissues, for example liquid endosperm, it is convenient to extract directly with a buffer solution at about pH 8 resulting in a cleaner extract (16). 

Small Quantities. Wear protective gloves, laboratory coat, and goggles. Work in the fume hood. If the aflatoxin is dissolved in an organic solvent other than methanol, remove the solvent under reduced pressure. Dissolve the residue in methanol and, for each microgram of aflatoxin, add 3 mL of household bleach (5% sodium hypochlorite solution). Shake the mixture and allow to stand at room temperature for at least 2 hours. Dilute the solution with five times its volume of water and then add acetone equal to one-twentieth of the total volume. Allow to react for 30 minutes. Wash the solution into the drain with water.4... 

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. 

Allow the mixture to cool to room temperature and add 10 mL of methanol. Remove the stirrer bar and pour the contents into a 250 mL round-bottomed flask. Remove the solvent on a rotary evaporator. 

Figure 39 shows a spectacular example of the selectivity of reactions of dibutylstannylene acetals of vicinal m-diols over isolated diols, for 2 -0-acetyltylosin, where one secondary hydroxyl of the three available reacts because it is the only one vicinal to another hydroxyl group. In the sequence shown, reflux in methanol removes the 2 -0-acetyl group.260... 

The addition provides only one stereoisomer out of the four possible ones. Sodium Amalgam reduction in buffered methanol removes the binaphthyl residue to afford the hydrocarbon and recovered starting dithiol. 

Methanol removes water without dissolving much anthracene... 

Methanol removal from mixtures with toluene, MTBE, IPA, and acetonitrile... 

Zhou M, Persin M, and Sarrazin J. Methanol removal from organic mixtures hy pervaporation using polypyrrol membranes. J. Memb. Sci. 1996 117(l-2) 303-309. 

Hemodialysis corrects any metabolic acidosis while removing methanol and formate [97] and should be considered with evidence of organ toxicity, presence of acidosis, and methanol levels greater than 50 mg/ dL. Fomepizole is dialyzable (see next section). Closure of the osmolal gap correlates with methanol removal and can be followed if methanol levels are unavailable or... 

In order to determine the major routes of methanol removal, a sensitivity analysis was done. The abstraction reaction... 

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