Charcoal treatment

The technical concentrated ether contains very smaH amounts of alcohol, water, aldehydes, peroxides, and other impurities (Table 5). The more refined grades, such as anesthetic ether, are obtained from technical ether by redistiHation and dehydration foHowed by alkaH or charcoal treatment. 

Bipyridyl [366-18-7] M 156.2, m 70.5 , b 273 , pK -0.52, pK 4.44. Crystd from hexane, or EtOH, or (after charcoal treatment of a CHCI3 soln) from pet ether. Also ppted from a cone soln in EtOH by addition of H2O. Dried in a vacuum over P2O5. Further purification by chromatography on AI2O3 or by sublimation. [Airoldi et al. J Chem Soc, Dalton Trans 1913 1986.]... 

Bromotetronic acid [21151-51-9] M 179.0, m 183°(dec), pK 2.23. Decolorised, and free bromine was removed by charcoal treatment of an ethyl acetate soln, then recrystd from ethyl acetate [Schuler, Bhatia and Schuler J Phys Chem 78 1063 1974]. 

Dissolved in a small volume of hot water and ppted with EtOH, twice. Repeated once more but with charcoal treatment of the aqueous soln, and filtered before addition of EtOH. 

Ncold water (400 ml) and stirred until the precipitated product turned granular (fifteen minutes). The crude product was collected, washed with cold water, and dried. Crystallization from Skellysolve B with charcoal treatment gave colorless crystals (6.65 g, 58%), MP 149°C to 150°C. The product was recrystallized twice from Skellysolve B to give ( )-6[Pg.355]

The free base was obtained from the hydrochloride by adding a slight excess of dilute ammonium hydroxide to the aqueous solution, and crystallizing the product from aqueous methanol. A further recrystallization with charcoal treatment gaye almost colorless needles, MP 110° to 112°C of ethyl N-phthaloyl p-aminophenylalaninate. 

The basic solution was chilled and poured into one-half volume of 1 3 acetic acid. Sufficient hydrochloric acid was added to bring the mixture to pH 4. The crude 3-sulfanilamido-6-chloropyridazine which precipitated was purified by solution in 6 parts of 1 100 ammonium hydroxide, charcoal treatment and precipitation by pouring of the filtrate into dilute acetic acid. 

Yields were improved by utilizing chemically modified charcoal [treatment with N,N-dimethylformamide dibutyl acetal (DMFBA) or N,0-bis(trimethylsilyl)acetamide (BSA)] due to suppression of H2O2 decomposition and ranged between 18 and 81%. Conversion and selectivity seem to depend extremely on the pre-treatment of charcoal with solutions of various pH values being highest for solutions with pH 7. 

The resulting solid is extracted with 400mL of boiling absolute ethanol with stirring for 30 min and while hot it is filtered leaving behind a small amount of insoluble brown residue. The filtrate is then cooled in an ice bath to precipitate the crude product, II, and filtered (2.95 g, 52% of theoretical yield). Subsequent recrystallization from ethanol (with charcoal treatment), or alternatively, column chromatography on partially deactivated silica gel, gradient eluted with chloroform-hexane, will yield analytically pure product. 

If the charcoal treatment is omitted, the acenaphthenol obtained is light yellow but practically pure. 

Chen, R. F. 1967. Removed of fatty acids from serum albumin by charcoal treatment. J. Biol Chem. 242, 173-181. 

The crude product contains some of the aromatic amino acid tyrosine which is present in the original hydrolysate. A portion of this is removed by the charcoal treatment and by the hot-water washing, but the final recrystallised cystine may be contaminated with tyrosine if the suggested 5-6 hour period for crystallisation is greatly exceeded. 

To evaluate the degree of microbial growth inhibition caused by the hydrolysate used, Debaryomyces hansenii was grown in detoxified hydrolysates and in a hydrolysate only subjected to a pH correction, both nonsupple-mented and supplemented. As detoxification methods, anion-exchange resins and activated charcoal treatments were chosen because both enable the reduction of most of the fermentation-inhibiting compounds (7,38,39). 

Approximately one part of hydrated lime for every two parts of liquor is added slowly over a one-hour period while the temperature is raised to about 95°C. The precipitated calcium citrate is filtered on a vacuum filter, and the filtrate, free of citrate, is discarded as waste. The calcium citrate cake is moved to acidulation tanks, where it is acidified with dilute sulfuric acid. It is then filtered, and the citric acid mother liquor is decolorized by a charcoal treatment. The purified liquor is concentrated in a vacuum evaporator, run into a crystallizer where, upon cooling, citric acid crystallizes, generally in the form of the monohydrate. The resulting acid is of USP grade. 

MeOH (50 ml) which was added over a period of 10 min. After refluxing for 1 h, the reaction mixture was cooled. A brown solid precipitated, which was filtered and washed with plenty of methanol and which yielded 15 g of product. The product was purified by repeated charcoal treatment and recrystallization from acetone, mp 124- 125°C. 

Polyethylene glycol48 Hydrogen peroxide Followed by an activated charcoal treatment... 

The submitters, starting with 266.3 g (2.77 mol) of furfural, obtained the product as colorless crystals, mp 57-59°C and found that, upon stirring the mother liquors at -78°C and seeding, an additional 70.3 g (total yield of 77%) of the butenolide could be obtained. The checkers noted that their product could be decolorized by charcoal treatment (twice) of a chloroform solution heated at reflux to furnish an analytically pure sample of the furanone with mp 54°C. The product displays the following spectral data H NMR (300 MHz, CDCy 5 5.24 (br s, IH), 6.23 (dd, 1.2, 5.4, IH), 6.27 (m, IH), 7.33 (dd,... 

A mixture of 500 g. (3.25 moles) of biphenyl and 208 g. (6.5 gram atoms) of sulfur is heated to 115-120°, and 25 g. (0.19 mole) of anhydrous aluminum chloride is added over a period of 75 minutes. The temperature is held at 115-120° for another 2 hours, followed by a gradual increase to 240° over a period of 5 hours. The cool residue is extracted with three 500-ml. portions of hot water and then with eight 1-1. portions of ethanol. Evaporation and cooling of the ethanolic solution after a charcoal treatment gives a 65-70% yield of dibenzo-thiophene melting at 98°. Material melting at 99° is obtained by distillation, b.p. 152-154°/3 mm., and recrystallization from ethanol. 

A mixture of 8.5 g. (0.047 mole) of fluorenone (p. 163), 6.6 g. (0.95 mole) of hydroxylamine hydrochloride, and 80 ml. of 70% ethanol is refluxed for 3 hours. The ethanol is removed by distillation and the residue treated with excess water. The resulting solid product is removed by filtration and washed thoroughly with water. The solid is recrystallized from ethanol with a charcoal treatment to give an 82% yield of the oxime, melting at 192-193°. 

---