Flash-chromatography

Pyrolvsis-Gas Chromatography. Flash pyrolysis analyses were performed according to previously described methods (3). In brief, samples were... 

I) Physical characteristics of the oil condition monitoring wear metals analysis, fuel contamination, viscosity, chromatography, flash point, water content, insoluble test, blotter test, direct reading ferrography, differential scanning calorimetry and colorimetry. 

Early isolation of brevetoxins from cell cultures relied heavily on thin-layer chromatography, flash chromatography, and high pressure liquid chromatography (HPLC) with ultraviolet (UV) detection... 

Extraction is a process of separation of active compounds from plant material using different solvents. Extract can be prepared using various methods, such as sonification, heating under reflux, Soxhlet extraction, maceration, and others. Different solvent systems are available to extract the bioactive compound from natural products. The solvent systems used in extraction are selected on the basis of their capacity to dissolve the maximum amount of desired active constituents and the minimum amount of undesired constituents. The extraction of hydrophilic compoxmds uses polar solvents such as methanol, ethanol, or ethyl acetate. For extraction of more lipophilic compounds, dichloromethane and a mixture of dichloromethane/methanol are used (Sasidharan et al. 2011). Due to the fact that extracts usually occur as a combination of various types of bioactive compounds or phytochemicals with different polarities, their separation to obtain pure compounds using different separation techniques such as TLC, column chromatography, flash chromatography, Sephadex chromatography, and HPLC is still required. The pure compounds are then used for the determinaticai of stracture and antimicrobial activity. 

In a Schlenk. flask, a solution of 1.03 g (2.70 mmol) terpyridinetriflate in 30-mL abs. tetrahydrofuran under argon atmosphere, 0.758 mL (0.531 g, 5.40 mmol) trimethyl-silylacetylene, 57.0 mg (81.0 mmol, 3 mol%) bis(triphenylphosphine)palladium(II) chloride, 51.0 mg (0.270 mmol, 10 mol%) copper(I) iodide, and 13.4 mL of diisopropylamine was added. The black mixture was stirred for 2.5 h at ambient temperature. Subsequently, 125 mg of activated charcoal was added, stirred for 15 min, and filtered then, the solvent was removed under reduced pressure. The black crude product was purified by column chromatography (flash silica gel, 4.5 x 25 cm, CH2Cl2/MeOH 19 1). This gave 0.874 g (2.65 mmol, 98%) of the alkyne as a red-brown solid mp 163 °C 0.05 (CH2Cl2/MeOH 19 1). ... 

Methoxy-l-methylethyl alkyl peroxides (1, X = OR , R = R = R" =, methyl R = decyl, undecyl, pentadecyl, 2-octyl) are Hquids that have been isolated using flash chromatography (131). Peroxyester derivatives (R = cyl) have also been prepared (131). 

Bonded Phases. Substrate-bond hydrocarbon coatings for high pressure Hquid chromatography (hplc) and flash chromatography are prepared from octyltrialkoxysilanes and other long-chain alkyltrialkoxysilanes (see Chromatography). 

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... 

This material Is purified by recrystallization from ethyl acetate acetone 2 1 (v v) to give a first crop (6.8 g), and by flash chromatography of the residue from the mother liquor, using 150 g of 230-400 mesh silica gel (Merck), a 40-mm diameter column, and elution with 10 1 (v v) ethyl acetate methanol. A fast moving orange band and a slower moving lemon-yellow band can be clearly seen on the column. The lemon-yellow hand is collected from the column and evaporation gives a second crop (1.4 g) of comparably pure material. The total yield of the pale yellow isoquinoline is 8.2 g (86t), mp 135-137°C (Note 10). 

Carbonate ionophore I [ETH 6010] (heptyl 4-trifluoroacetylbenzoate) [129476-47-7] M 316.3, b 170°/0.02 Torr, d 0.909. Purified by flash chromatography (2g of reagent with 30g of Silica Gel 60) and eluted with EtOAc/hexane (1 19). The fractions that absorbed at 260nm were pooled, evapd and dried at room temp (10.3 Torr). The oily residue was distd in a bubbled-tube apparatus (170°/0.02 Torr). Its IR (CHCI3) had peaks at 1720, 1280, 940cm and its sol in tetrahydrofuran is 50mg/0.5mL. It is a lipophilic neutral ionophore selective for carbonate as well as being an optical humidity sensor. [Anal Chim Acta 233 41 1990.]... 

Chromoionophore I [ETH 5294] [9-diethylamino-5-octadecanoyl-imino-5-//-benzo[a]-phenoxazine] [125829-24-5] M 583.9. Purified by flash chromatography (Silica Gel) and eluted with EtOAc. The coloured fractions are pooled, evaporated and recrystd from EtOAc. It is a lipophilic chromoionophore and is a selectophore for K and Ca ions. [Anal Chem 62 738 7990.]... 

M 340.6. Purified by flash chromatography (at 40 kPa) on silica and eluting with EtOH-hexane (4 1). IR has v(CHCl3) 1630cm. [Helv Chim Acta 63 2271 1980.] It is a good magnesium selectophore compared with Na, K and Ca [Anal Chem 52 2400 7950]. 

Magnesium ionophore II (ETH 5214), [A/,A/"-octamethylene-bis(A/ -heptyl-)V"-methyl methylmalonamide)] 1119110-37-1] M 538.8. Reagent ca 700mg) can be purified by flash chromatography on Silica Gel 60 (30g) and eluting with CH2Cl2-Me2CO (4 1). [Anal Chem 61 574 1989.]... 

To a solution of m-ethyl cinnamate (44, 352 mg, 85% pure, 1.70 mmol) and 4-phenylpyridine-A-oxide (85.5 mg, 29 mol%) in 1,2-dichloromethane (4.0 mL) was added catalyst 12 (38.0 mg, 3.5 mol%). The resulting brown solution was cooled to 4°C and then combined with 4.0 mL (8.9 mmol) of pre-cooled bleach solution. The two-phase mixture was stirred for 12 h at 4°C. The reaction mixture was diluted with methyl-t-butyl ether (40 mL) and the organic phase separated, washed with water (2 x 40 mL), brine (40 mL), and then dried over Na2S04. The drying agent was removed by filtration the mother liquors concentrated under reduce pressure. The resulting residue was purified by flash chromatography (silica gel, pet ether/ether = 87 13 v/v) to afford a fraction enriched in cis-epoxide (45, cis/trans . 96 4, 215 mg) and a fraction enriched in trans-epoxide cis/trans 13 87, 54 mg). The combined yield of pure epoxides was 83%. ee of the cis-epoxide was determined to be 92% and the trans-epoxide to be 65%. 

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