Chromatography of ethers

Kesner, L., E. Mundtwyler, G. E. Griffin, and J. Abrams Automatic column chromatography of ether-soluble and water-soluble 2,4-DNP-derivatives of amino acids, peptides and amines. Analytic. Chem. 35, 83-89 (1963). 

The noncarbohydrate fraction can indeed be traced to lignin source. Gas-liquid chromatography of ether extracts of the washer liquors indicates the presence of guaiacol syringaldehyde, vanillin, vanillic acid, syringic acid, and hydroxybenzoic acid. 

Carbofuran and its degradation products carbofuranphenol, 3-keto-carbofuran, 3-hydroxycarbofuranphenol, Y-hvdroxymethylcarbofiiran and 3-hydroxycarbofuran, have been determined in water samples by thin layer chromatography of ether extracts of the sample [23],... 

Subsequently, SieUcki et aL [11] described a styrene-utilizing mixed culture enriched from landfill soil in mineral salts medium with 1% (w/v) styrene. Thin-layer chromatography of ether extracts of the styrene-degradi cultures showed phenylacetic acid and a second compoimd, which was tentatively identified as 2-phenylethanol to be present. 

Neutral lipids represent another group of antihypertensive agents from the renal medulla [147,149,150]. Isolation was accomplished by chromatography of ether extracts of renal medulla. A highly refined product described by Muirhead et al. [150 a] contained two or more components and was active against hypertension in rabbits at a dose of 2 [Xg/kg. The product lowered the arterial pressure of hypertensive animals within 12-24 hours. The pressure returned to prior hypertensive levels within several days after one to two parenteral doses. 

The product may also be purified by flash chromatography using 19/1 (v/v) petroleum ether, (bp 3Q-60 C)/ethyl acetate as eluant. A column of 2-cm diameter was packed to a height of 25 cm with Kieselgel 60 (230-400 mesh) supplied by BOH Chemicals Ltd. In one run chromatography of 4.19 g of crude product afforded 3.70 g (88%) of the a.g-unsaturated ester which was... 

Toluene is a useful co-solvent in metal-ammonia reductions as first reported by Chapman and his colleagues. The author has found that a toluene-tetrahydrofuran-ammonia mixture (1 1 2) is a particularly useful medium for various metal-ammonia reductions. Procedure 8a (section V) describes the reduction of 17-ethyl-19-nortestosterone in such a system. Ethylene dibromide is used to quench excess lithium. Trituration of the total crude reduction product with methanol affords an 85% yield of 4,5a-dihydro-17-ethyl-19-nortestosterone, mp 207-213° (after sintering at 198°), reported mp 212-213°. For the same reduction using Procedure 5 (section V), Bowers et al obtained a 60% yield of crude product, mp, 196-199°, after column chromatography of the total reduction product. A similar reduction of 17-ethynyl-19-nortestosterone is described in Procedure 8b (section V). The steroid concentration in the toluene-tetrahydrofuran-ammonia system is 0.05 M whereas in the ether-dioxane-ammonia system it is 0.029 M. 

Androst-4-ene-3,l7-dione 3-Ethylene Thioketal A solution of androst-4-ene-3,17-dione (1.42 g, 5 mmoles) in acetic acid (20 ml) is treated with ethanedithiol (0.47 g, 5 mmoles) and a solution of 0.45 of p-toluenesulfonic acid monohydrate in acetic acid (5 ml). After 1 hr at room temperature, the pale yellow solution is poured into water and the resulting suspension is extracted with chloroform. The chloroform solution is washed with water, 5 % sodium hydroxide solution and water, dried (Na2S04) and evaporated. Chromatography of the resulting oil (1.93 g) over silica gel yields androst-4-ene-3,17-dione bisethylene thioketal, mp 173-175° [0.16 g, eluted with petroleum ether-benzene (1 2)] and androst-4-ene-3,17-dione 3-ethylene thioketal, mp 173-176° [1.38 g (76%), eluted with benzene-ethyl acetate (19 1)]. 

A solution of 0.38 g of the diazoketone in 2 ml of acetic acid is heated 0.5 hr at 100-105°. Removal of the solvent under reduced pressure and crystallization of the residue from acetone-ether gives 0.27 g of 1 la,21-dihydroxy-pregn-4-ene-3,20-dione 11,21-diacetate mp, 144-146° [a]o 156° (CHCI3). An additional 60 mg of this product is obtained by chromatography of the mother liquor (total yield 72%). 

After an additional 10 min, a 1 % solution of hydrochloric acid (100 ml) is slowly added to the stirred reaction mixture and the resultant mixture is transferred to a separatory funnel. The ether layer is separated and washed sequentially with water, 5 % sodium bicarbonate solution, water and saturated salt solution. The washed ether solution is dried over anhydrous sodium sulfate, filtered, and evaporated to give an oily residue (0.45 g). Chromatography of the crude product on silica gel (50 g) followed by crystallization of the solid thus obtained (0.18 g) from ethanol gives 3 -hydroxy-B-homo-cholest-5-en-7a-one acetate (67 0.14 g) mp 90-91° [a]o 99° (CHCI3). 

After stirring for 1 hr more, the reaction mixture is diluted with 500 ml of cold water the yellow precipitate which forms is filtered, washed and dried, to give 4.1 g (83%) of crude 16-diazoestrone methyl ether (94) mp 133-136°. Chromatography of the crude product over neutral alumina in chloroform, followed by recrystallization from chloroform-methanol, gives pure (94) mp 145-146°, in 64% over-all yield. ... 

After the end of the fermentation (28 hours) the culture broth is filtered off by suction over a large suction filter. The mycel residue is washed with water several times. The filtrate is extracted three times, each time with 10 liters of methyl isobutyl ketone. The extract is concentrated under vacuum in a circulating evaporator and in a round flask carefully dried under vacuum. The residue is crystallized from acetone/isopropyl ether. The melting point is 157°-158°C (fermentation yield = 60%). The pure product yield obtained after a second crystallization and chromatography of the mother liquor on silica gel amounts to 53% of the theoretical. 

ID) Obtaining Ethyl [3-l6-Methoxy-2-Naphthyl)J2,2-Dimethyl Pentanoate by Hydrogenation of the Previous Ethylene Ester 3.5 g of the previous ethylene ester, purified by chromatography, are hydrogenated in the presence of 3.6 g of platinum in 30 cc of ether. The quantity of hydrogen fixed corresponds to the theoretical quantity calculated. After filtering, the ether is evaporated, 3.45 g of ester are thus obtained in the form of an oil which quickly solidifies. Purification is effected by chromatography. 

From the reaction of 5-0-benzoyl-l,2-0-isopropylidene-o -D-en/t/iro-pentofuranos-3-ulose (prepared in 80% yield by oxidation of 5-0-benzoyl-l,2-0-isopropylidene- -D-xylofuranose (35,36) with ruthenium tetroxide) with an excess of diazomethane in methanol-ether, two main products (m.p. 44°-45°C. and 76°-77°C.), both epoxides, could be isolated by chromatography of the product on a silica column. An... 

A mixture of the sodium salt 7 (1.8 g, 4.7 mmol) and DME (90 mL) was refluxed for 30 min, cooled and filtered through Celite. Evaporation under reduced pressure was followed by chromatography of the residue (silica gel, Et20/petroleum ether 1 1) yield 0.81 g (76%) yellow crystals mp 103-104 C (EtOH). 

BuLi in hexane (6 mmol) was added dropwise to the dibenzotriazepine 1 a (0.980 g, 5 mmol) in THF (40 mL) under N2 at — 30 C. The mixture was stirred for 30 min, treated with a large excess of Mcl, allowed to warm to 20 C and stirred overnight. Evaporation, followed by chromatography of the residue (alumina, Et20/petroleum ether 1 9) gave the product yield 0.730 g (67%) yellow crystals mp 66-67 C. 

I2 (0.0267 g, 0.21 mmol) in THF (1 mL) was added to a suspension of the mercury derivative 17 (0.0093 g. 0.016 mmol) in THF. The mixture was added to H20 (2 mL) and the resulting suspension was extracted with EtzO (2x5 mL). The combined extracts were washed with H20 (2 mL), dried (MgSQ4) and evaporated. The oily residue was submitted to flash chromatography (petroleum ether) yield 4.5 mg (89%) yellow-orange crystals mp 62 — 63 C (Et20/petroleum ether). 

A solution of 3.7I g (0.013 mol) of tributyltin hydride in 10 mL benzene is added dropwise to a solution of 3.09 g (0.011 mol) of S-[(S)-4-(benzyloxy)-3-pentenyl] 5-methyl carbonodithioate in 25 mL of degassed, anhyd benzene under an atmosphere of argon, followed by 5 mg of AIBN. The mixture is heated under reflux for 2.5 h and then is concentrated under reduced pressure. Flash chromatography of the residue using ht,0/petroIeum ether 1 50 containing 1 % triethylamine as eluant gives a colorless oil yield 3.87 g (78%) [a] - 26 (e = 1. CHCl3). 

A mixture of 200 mg (1.9 mmol) of benzaldehyde and 1.35 g (3.8 mmol) of ( )-tributyl(l-mcthyl-2-butenyl)stannane [containing ca. 10% of its (Z)-isomer] is heated to 150 °C for 18 h in a sealed tube. Flash chromatography of the orange residue (silica gel, Ei20/peti oIeuni ether 1 5) gives a pale yellow oil yield 240 mg (72%) analyses by H NMR. 

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