Preparative chromatography columns

Sodium ionophore VI bis[(12-crown-4)methyl]dodecyl methyl malonate [80403-59-4] M 662.9. Purified by gel permeation or column chromatography. [Preparation and NMR data J Electroanal Chem 132 99 1982.]... 

Lipopholic products are usually separated by extraction of the filtered broth, or the whole culture including the biomass, with water immiscible organic solvents, followed by separation of the solvent extracts and concentration in a vacuum evaporator. Chloroform, dichloromethane and ethyl acetate have been widely used as extraction solvents, however, 4-methyl-2-pentanone (methyl isobutyl ketone) appears to be the solvent of choice in the case of steroid substrates. Hydrophilic products, which cannot be extracted by organic solvents, can be isolated by ion exchange or by selective adsorption to polymeric resins (e.g., Amberlite XAD-resins). Resins of a wide range of polarity are available and lipophilic compounds can also be separated by this method. Final purification is accomplished in the usual way by crystallization, distillation or column chromatography. Preparative HPLC is a powerful tool for purification of small product quantities. 

Purify it by gel permeation or column chromatography. [Preparation and NMR data Shono et al. J... 

The nitration of the 2-anilino-4-phenylselenazole (103) is much more complicated. Even careful nitration using the nitrate-sulfuric acid method leads to the formation of a mixture of variously nitrated compounds in an almost violent reaction. By the use of column chromatography as well as thin-layer chromatography a separation could be made, and the compounds could be partly identified by an independent synthesis. Scheme 33 shows a general view of the substances prepared. Ring fission was not obser ed under mild conditions. 

Until separation techniques such as chromatography (28,29) and counter-current extraction had advanced sufficientiy to be of widespread use, the principal alkaloids were isolated from plant extracts and the minor constituents were either discarded or remained uninvestigated. With the advent of, first, column, then preparative thin layer, and now high pressure Hquid chromatography, even very low concentrations of materials of physiological significance can be obtained in commercial quantities. The alkaloid leurocristine (vincristine, 22, R = CHO), one of the more than 90 alkaloids found in Catharanthus roseus G. Don, from which it is isolated and then used in chemotherapy, occurs in concentrations of about 2 mg/100 kg of plant material. 

Preparation of soil—sediment of water samples for herbicide analysis generally has consisted of solvent extraction of the sample, followed by cleanup of the extract through Uquid—Uquid or column chromatography, and finally, concentration through evaporation (285). This complex but necessary series of procedures is time-consuming and is responsible for the high cost of herbicide analyses. The advent of soUd-phase extraction techniques in which the sample is simultaneously cleaned up and concentrated has condensed these steps and thus gready simplified sample preparation (286). 

Nltroestrone (2)/ Claylen was prepared from a mixture of Fe(N03)3 H2O (45 g Oil mol), K 10 bentonite clay and MeaCO (750 mL) Freshly prepared Claylen" (2 0 g) was added to estrone 1 (0 54 g 2 mmol) and PhMe (150 mL) The suspension was slirred overnight at 20° and filtered under vacuum The yellow liltraie was purified by column chromatography on sdica gel (n-hexane ElOAc 8 2] Evaporation of the corresponding fraction afforded 0 347 g of 2 (55%) mp 178 180°C... 

TLC can be used as an analytical technique, or as a guide to establishing conditions for column chromatography or as a preparative technique in its own right. 

Butylcyclohexanol has been prepared from />-/-butylphenol by reduction under a variety of conditions.3 4 Winstein and Holness5 prepared the pure trans alcohol from the commercial alcohol by repeated crystallization of the acid phthalate followed by saponification of the pure trans ester. Eliel and Ro 6 obtained 4-f-butylcyclohexanol containing 91% of the trans isomer by lithium aluminum hydride reduction of the ketone. Iliickel and Kurz 7 reduced />-/-butylphenol with platinum oxide in acetic acid and then separated the isomers by column chromatography. 

A mixture of 4,5-di(pentyloxy)phthalonitrile (A 69 mg, 0.23 mmol), 3,4,5,6-tetraphenylphthalonitrile (B lOOmg, 0.23 mmol), Ni(0Ac)2 (35 mg, 0.2mmol). and catalytic amounts of DBU in pentan-l-ol (3mL) was heated under N2 for 24 h under reflux. The cooled blue-green solution was poured into MeOH/H20 (5 1, 50 mL), and the precipitate formed was centrifuged, washed with MeOH, and dried in vacuo. The separation of the prepared compounds was performed by column chromatography (toluene/hexane 1 1). The fractions were collected and the solvent evaporated. The order of elution was ABBB (0.5 mg, 0.1 %), ABAB (7.5 mg, 1.4%), AABB (2 mg, 0.5%), AAAB (15 mg, 2.3%) and AAAA (9 mg, 1.6%). No BBBB-type phthalocyanine was formed. 

An improved method of producing recombinant aequorin was devised based on the fact that the expression of the peak amount of apoaequorin in bacterial cells occurs several hours before the secretion into culture medium (Shimomura and Inouye, 1999). The cells containing apoaequorin in the periplasmic space, before secretion, are extracted under a very mild condition and, at the same time, converted into aequorin. The purification of the extract by two steps of column chromatography yields a high-purity preparation of recombinant aequorin. 

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