Charcoal Darco

Adsorbents. Macroreticular Amberlite resins XAD-2 and XAD-4 (20-50 mesh Lots 90721 and 89829, respectively) were obtained from BDH Chemicals Ltd. Polyurethane foam (upholstery grade, Woodbridge Foam Co.) and vegetable charcoal (Darco G-60 Lot 363-53 Matheson Canada Ltd.) were purchased. 

The residues, eluted with mixture water-acetone, were combined and chromatographed through a 50 g 1 1 charcoal (Darco)-diatomaceous earth (Celite) column. The column was developed with solvent of the following composition and order methanol, a 1 1 mixture of methanol and acetone, a 1 2 mixture of methanol and acetone, acetone and a 1 4 mixture of acetone and methylene chloride. Fractions, containing 7(a)-epimer were combined, the solvent evaporated and the residue crystallized from acetone to give the 7a,17-dimethyltestosterone, melting point at 163° to 165°C. 

In methylene chloride (3 L) was dissolved m-chloropropiophenone (698.0 g 4.15 mole). The solution was stirred with charcoal (Darco) and magnesium sulfate for 2 h and filtered. To it was added with stirring (662.0 g) of bromine in methylene chloride (1 L). When the bromine color had faded completely, the solvent was evaporated in vacuum and m-chloro-a-bromopropiophenone was obtained as oil. 

Acid Hydrolysis. Twenty-five milliliters of 6N hydrochloric acid was added to 250 mg. of dry sample and the suspension was refluxed for 16 hours. The excess hydrochloric acid was removed by evaporation on a steam bath or on a rotary vacuum evaporator. The amino acids were then dissolved in 20 ml. of 10% 2-propanol. Samples so prepared were used directly for analysis by paper chromatography. Those samples to be analyzed by ion exchange chromatography were decolorized with a small amount of charcoal (Darco G-60) and filtered through paper. A 2-ml. aliquot of the filtrate was dried and redissolved in sodium citrate buffer at the pH and molarity required for application to the resin. 

A 0.200-g ground sample of tobacco is weighed into a 250-ml Erlenmeyer flask with a ground glass stopper. Also added to the flask is 0.5 g of activated charcoal (Darco G-60 phosphate-free) to remove interfering color, and 100 ml of extraction solution. The samples are extracted for 5 min on a fast action shaker and then filtered through Whatman 1 filter paper. 

The crude product containing a considerable amount of a black contaminant is dissolved in a minimum amount of warm water (70°), treated with decolorizing charcoal (Darco), and filtered. To the filtrate is added slowly one to two volumes of ethyl alcohol until a golden-yellow crystalline solid separates. This purification process may be repeated if a product of higher purity is desired. The crystals are collected on a Buchner funnel, washed with alcohol, then ether, and finally dried in a vacuum. 

On the whole it is better to employ the activated decolourising charcoal prepared from wood. Excellent decolourising carbons are marketed under the trade names Norit (from birch wood), Darco and Nuchar. ... 

Charcoal is generally satisfactorily activated by heating gently to red heat in a crucible or quartz beaker in a muffle furnace, finally allowing to cool under an inert atmosphere in a desiccator. Good commercial activated charcoal is made from wood, e.g. Norit (from Birch wood), Darco and Nuchar. If the cost is important then the cheaper animal charcoal (bone charcoal) can be used. However, this charcoal contains calcium phosphate and other calcium salts and cannot be used with acidic materials. In this case the charcoal is boiled with dilute hydrochloric acid (1 1 by volume) for 2-3h, diluted with distilled water and filtered through a fine grade paper on a Buchner flask, washed with distilled water until the filtrate is almost neutral, and dried first in air then in a vacuum, and activated as above. To improve the porosity, charcoal columns are usually prepared in admixture with diatomaceous earth. 

Activated charcoal, purified - place about 50 g Darco C-5 activated carbon in a wide-neck screw-cap container, add sufficient calcium phosphate extractant to completely wet it, then cap the bottle and shake for 5 min. Filter slowly with suction through a Buchner funnel, then wash three times successively with deionized water. Test the final leachate with a solution of barium chloride (approximately 1.4% m/v in 0.3 M HCI). If turbidity indicates the presence of sulphate, return the charcoal to a beaker, thoroughly mix with deionized water (boil for 15 min if necessary to get a clear test), refilter, wash and test for S as above. When satisfactory, dry overnight at 105°C and store in a tightly capped bottle. 

Decolourising carbon, 127, 128 animal charcoal, 128 Darco, Norit, Nuchar, 128 D.D.T., 1011, 1012... 

Preliminary Purification of Lima Bean and Alfalfa. The pH 7 buffer solution was washed once with ethyl acetate, acidified to pH 2 with sulfuric acid, and extracted several times with ethyl acetate. The combined ethyl acetate extracts were evaporated under reduced pressure below 40° C. The residue was dissolved in pH 7 buffer and then added to a charcoal column (10 grams of 1 1 Darco G-60-crushed glass particles). The column was eluted with 95% acetone, the eluate was evaporated to dryness, and the residue was taken up in methanol. 

At the end of the incubation period, the culture was filtered through Whatman No. 1 paper, and 1 gram of Darco G-60 charcoal was added to the filtrate. This suspension was agitated on the shaker for 1 hour and then filtered. The charcoal was air-dried and eluted once with 80% aqueous acetone. The eluate was concentrated to about 5 ml. in vacuo and was finally lyophylized. 

The medium is adjusted to pH 7.0 prior to sterilization for 20 minutes at 121°C. The fermentation flasks are incubated and agitated under similar conditions as the germination flasks. After 72 hours the mycelium was separated by centrifugation and the untreated broth assayed by the streak dilution method. 30 liters of broth are centrifuged and 6% of Darco G-60 charcoal is added to the clear solution, which is stirred for 30 minutes then the charcoal is filtered off to give an almost colorless solution which is concentrated in vacuum at 45-50°C to 1.5 liters. The concentrated solution is poured under stirring into 5 liters of methanol, the formed precipitate is... 

The fermentation mixtures from the four fermenters are combined and filtered with the aid of diatomaceous earth, A material such as Celite 545 can be used. The filtrate is concentrated under reduced pressure to a volume of 10 liters, and the concentrate is treated with 200 grams of activated charcoal (for example, Darco G-60), stirred at room temperature for one hour, and filtered. The charcoal cake is washed with 7.5 liters of water, and then extracted with three 10-liter portions of 50% aqueous acetone. The three aqueous acetone extracts are combined, concentrated under reduced pressure to approximately one liter, and chilled at 5°C for 48 hours. The solid 9-( 5-D-arabinofuranosyljadenine that precipitates is isolated and purified by successive crystallizations from boiling methanol and from boiling water MP 262° to 263°C. 

The checkers used Darco G-60 charcoal from Matheson Coleman and Bell. It appeared to be very fine and plugged the filter during filtration. Norit A is recommended. 

Activated charcoal (20-40 mesh) was used as received from Matheson, Coleman, Bell or Darco (G-60). Addition of charcoal at this stage removes reduces the amount of malodorous thiol impurities. 

A. Tiselius, Advances in Colloid Set., 1, 89 (1942) Kahlbaum active carbon, Carboraffin, Supranorit, Merck animal carbon, and Merck blood charcoal were found useful in these separations. Norit P-3, Carboraffin Supra, and Darco G-60 were used subsequently. 

Activated charcoal powder - specified to be low in P (for example Darco G60). 

Ordinary animal charcoal and Darco gave equally good results. 

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