Sulfate removal

A mixture of 100 ml of water and 0.10 mol of methylthioallene (see Chapter IV, Exp. 23) was placed in the flask and 24 g of sodium periodate were added in five portions at intervals of 4 min. The mixture was agitated vigorously and the temperature was kept between 25 and 30°C by occasional cooling. After 1 h twenty extractions with 10-ml portions of chloroform were carried out. The combined extracts were dried (without previous washing) over magnesium sulfate. Removal of the chloroform by evaporation in a water-pump vacuum gave the reasonably pure (> 9i%) le... 

Enzymes for Liming and Bating. An important discovery (79) for the leather industry was the close relationship between the amount of dermatan sulfate removed and the degree of opening up. Until this discovery, the use of enzymes during the liming and unhairing steps was not considered worthwhile. 

Oxides of sulfur react with copper oxide to form copper sulfate. Removal with a dry particulate control system follows. 

The solid is separated by filtration and the filtrate is extracted with three 150-ml. portions of ether. Caution Gloves should be worn when handling this solution because of the large amount of cyanide it contains.) The solid is dissolved in ether and this solution is combined with the extracts. The combined ethereal solutions are washed with water and dried over 5 g. of sodium sulfate. Removal of the solvent by distillation leaves crude ferrocenyl-acetonitrile as a solid or as an oil that crystalli/.es on being scratched. I he nitrile is dissolved in about 200 ml. of boiling... 

A solution of cholest-4-en-3-one (139), 1 g, in diethylene glycol dimethyl ether (20 ml) is treated for 1 hr with a large excess of diborane at room temperature under nitrogen and then left for a further 40 min. Acetic anhydride (10 ml) is added and the solution refluxed for 1 hr. The mixture is concentrated to a small volume, diluted with water and extracted with ether. The extracts are washed with 10% sodium hydroxide solution, then with water and dried over sodium sulfate. Removal of the solvent leaves a brown oil (1.06 g) which is purified by chromatography on alumina (activity I). Hexane elutes the title compound (141), 0.68 g mp 76-77°. Successive crystallization from acetone-methanol yields material mp 78-79°, [a]p 66°. 

A mixture of 17 g of the methiodide and 32 ml of a 40 % aqueous potassium hydroxide solution is heated with stirring in a flask fitted with a condenser. The heating bath should be kept at 125-130°, and the heating should be continued for 5 hours. The cooled reaction mixture is then diluted with 30 ml of water and washed twice with 25-ml portions of ether. The aqueous layer is cautiously acidified in the cold with concentrated hydrochloric acid to a pH of about 2 and then extracted five times with 25-ml portions of ether. The combined extracts are washed twice with 10% sodium thiosulfate solution and are dried (magnesium sulfate). Removal of the solvent followed by distillation affords about 3 g of 4-cyclooctene-l-carboxylic acid, bp 125-12671-1 mm. The product may solidify and may be recrystallized by dissolution in a minimum amount of pentane followed by cooling in a Dry-Ice bath. After rapid filtration, the collected solid has mp 34-35°. 

Catalysis by PhosphorousPentoxide (7) A 500-ml round-bottom flask is charged with a mixture of 1-ethynylcyclohexanol (40 g, 0.32 mole), 250 ml of dry benzene, and 10 g of phosphorous pentoxide. (The addition of the phosphorous pentoxide may be attended by considerable heating if the benzene is not well dried no particular disadvantage is found in this case, providing provision for initial cooling is made.) A condenser is attached to the flask, and the contents are refluxed gently (steam bath) for 2 hours. The cooled solution is then decanted from the phosphorous pentoxide, washed once with bicarbonate solution, and dried (anhydrous sodium sulfate). Removal of the benzene (rotary evaporator) and fractionation of the residue affords the desired product, bp 85-88°/22 mm, 1.4892, about 25 g (61 %). 

Comparison of Sulfate Removal in Samples of Nitrocellulose by Acid Boil... 

Anhydrous calcium sulfate removes the water formed in the oxidation. 

Downstream extraction. The culmre broth was diluted with ethyl acetate and the aqueous phase separated using a separation funnel. The organic layer was collected and dried over anhydrous sodium sulfate. Removal of the solvent by rotary evaporator gave (5)-7-methyl-2-oxepanone as a light yellow oil (6.5 g, 38 % yield). Chiral-phase GC showed 99 % ee and >97 % purity. EI-MS and NMR confirmed the product. Note the unconverted (R)-2-methyl cyclohexanone evaporated completely under the aeration conditions used during the overnight incubation. 

B. 2-Methoxycyclooctanone oxime. In a 500-ml., three-necked, round-bottomed flask, fitted with a mechanical stirrer, a dropping funnel, and a reflux condenser equipped with a calcium chloride tube, is placed a solution of 53.5 g. (0.252 mole) of crude 2-chlorocyclooctanone oxime hydrochloride in 250 ml. of methanol. While cooling the vessel with running water, 60.7 g. of triethyl-amine (0.60 mole) is added dropwise during 40 minutes. The reaction temperature is kept below 50° and the reaction is continued for 30 minutes with stirring. After removal of methanol under reduced pressure using an efiicient rotatory evaporator, a light brown semisolid is obtained it is treated with 200 ml. of ether and 200 ml. of water to effect complete solution. The ether layer is separated and the aqueous layer is further extracted twice with ether. The combined ether solution is washed with saturated sodium chloride and dried over sodium sulfate. Removal of ether affords 42.8 g. of crude 2-methoxycyclooctanone oxime (Note 3) as a brown oil. 

B. Hydrogenolysis of the Phenolic Ether Biphenyl. To a solution of 10 g. (0.032 mole) of the product from Part A in 200 ml. of benzene is added 2 g. of 5% palladium-on-charcoal, and the mixture is shaken with hydrogen in a Parr apparatus at 40 p.s.i. and 35-40° for 8 hours (Note 3). The mixture is filtered, and the insoluble residue is washed with three 100-ml. portions of hot ethanol (Note 4). The filtrates are combined, and the solvent is removed by means of a rotary evaporator at 60° (12 mm.) to leave a solid residue. The product is dissolved in 100 ml. of benzene, and 100 ml. of 10% sodium hydroxide solution is added. The mixture is shaken, and the layers are separated. The aqueous layer is extracted with 100 ml. of benzene, and the original benzene layer is washed with 100 ml. of water (Note 5). The benzene solutions are combined and dried over magnesium sulfate. Removal of the benzene by distillation yields 4.0-4.7 g. (82-96%) of biphenyl as a white powder, m.p. 68-70° (Note 6). The infrared spectrum is identical with that of an authentic sample, and a purity of at least 99.5% was indicated by gas chromatography analysis. 

The slightly deliquescent sodium (1-hydrate) and anhydrous potassium salts are readily obtained by metathesis of the barium salt in hot water with the requisite amounts of sodium or potassium sulfate, removal of the barium sulfate that forms, and evaporation of the filtrate. 

The anhydrous sodium sulfate removes water from the sample. 

Dry pigment-rich diethyl ether layer by passing through approximately 50 to 100 mg of anhydrous sodium sulfate. Remove solvent under a stream of nitrogen. 

A mixture of 4-methoxybenzyl alcohol le (5 mmol) and acetic anhydride (5 mmol) in a beaker covered with watch glass was irradiated by microwaves for 10 min (heating and cooling at the interval of 1 min). After completion of die reaction (TLC), the product was extracted with ether (3x15 mL). The ether layer was washed with 10% NaOH and then dried with anhydrous sodium sulfate. Removal of the solvent under reduced pressure gave 4-methoxybenzyl acetate 2e in excellent yield (95%). 

Mechanisms of Sulfate Removal from the Water Column... 

A mixture of ethyl l-cyclopropyl-6,7,8-trifluoro-l,4-dihydro-4-oxoquinoline-3-carboxylate (933 mg), 3-acetamidopiperidine (710 mg), triethylamine (400 mg) and dimethylsulfoxide (10 ml) was heated at 100°C for 2 hours with stirring. Thereafter the mixture was cooled down and ice water was added thereto. The resulting mixture was extracted with chloroform and the chloroform layer was washed with water three times before being dried over anhydrous sodium sulfate. Removal of the solvent in vacuum followed by purification by silica gel column chromatography (chloroform-ethanol) gave ethyl 7-(3-acetamidopiperidin-l-yl)-l-cyclopropyl-6,8-difluoro-l,4-dihydro-4-oxo quinoline-3-carboxylate (930 mg). Re-crystallization from ethanol-ether afforded a colorless crystalline substance (MP 217°-218°C). 

A solution of 4.9 g (12.8 mmol) of methyl-l-(p-nitrobenzoyl)-5-methoxy-2-methyl-3-indolylacetate in 40 ml of acetic acid containing 400 mg of p-toluene-sulfonic acid is refluxed for 20 hours and then concentrated in vacuum. The gummy residue is extracted with ethyl acetate. The extract is filtered from insoluble material, washed with water and dried over sodium sulfate. Removal of the solvent under reduced pressure affords the desired product as yellow crystals MP 185-186°C. 

Sodium selenocyanate, 2 186, 187 Sodium selenopentathionate 3-hydrate, 4 88, 89 Sodium sulfate, removal of, in... 

Encouraging improvements in platinum dispersion and decline in sulfate content were observed- However, it was decided to repeat the sulfate removal step to bring down the sulphate content to less than 0 04%wt> which took another 24 hrs. The maximum H2S content... 

Ethyl 2-butyrylacetate. In a 1-L, three-necked, round-bottomed flask fitted with a mechanical stirrer, dry nitrogen inlet, and thermometer is placed 19.8 g (0.150 mol) of monoethyl malonate (Note 1), 350 mL of dry tetrahydrofuran (THF, Note 2), and 5 mg of 2,2 -bipyridyl. The solution is cooled to approximately -70°C (in an isopropyl alcohol-dry ice bath) and a 1.6M solution of n-butyllithium in hexane is added from a dropping funnel while the temperature is allowed to rise to approximately — 10°C. Sufficient n-butyllithium is added (approx. 190 mL) until a pink color persists for several minutes (Note 3). The heterogeneous solution is recooled to -65°C and 7.90 mL (7.98 g, 75 mmol) of iso-butyryl chloride (Note 4) is added dropwise over 5 min. The reaction solution is stirred for another 5 min (Note 5) and then poured into a separatory funnel containing 500 mL of ether and 300 mL of cold, 1 N hydrochloric acid (Note 6). The funnel is shaken, the layers are separated, and the organic phase is washed with two 150-mL portions of saturated aqueous sodium bicarbonate, followed by 150 mL of water, and dried over anhydrous sodium sulfate. Removal of the solvents under reduced pressure leaves 11.70 g (98%) of ethyl 2-butyrylacetate (Note 7). The crude product can be distilled at 70-74°C (7 mm) (80% yield, 96% purity by GLC). 

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