Recrystallization activated charcoal

A mixture consisting of 4 grams of 1,2,3,4-tetrahydro-4,4-dimethyl-7-methoxy-isochromane-dione-(1,3) (MP 95° to 97°C), 2.53 grams of 4-aminosulfonyl-phenyl-(2)-ethylamine and 150 ml of xylene was heated for 2 hours at its boiling point in an apparatus provided with a water separator. Thereafter, the reaction mixture was allowed to cool and was then vacuum-filtered, and the filter cake was recrystallized from n-propanoi in the presence of activated charcoal. 2.9 grams (58% of theory) of 1,2,3,4-tetrahydro-4,4-dimethyl-2-(p-amino-sulfonylphenyl-(2)-ethyl]-7-methoxy-isoquinolinedione-(1,3), MP 203° to 205°C, of the formula below were obtained. 

The crude iodinated acid was then dissolved in 500 ml of 95% alcohol, 10 g of dimethyl-aminoethanol was added, the solution was decolorized with activated charcoal and filtered at 70°C. After keeping the filtrate for several hours at 5°C, the heavy crystalline precipitate which formed was collected by filtration and washed with acetone. The mother liquors were concentrated to 150 ml and cooled to give a second crop which was further purified by recrystallization from 50 ml of 95% alcohol. In this way a total of 36.0 g of dimethyl-aminoethanol salt of dextro-/3-(3,5-diiodo-4-hydroxy)-o-phenylpropionic acid, MP 151° to 153°C, was obtained. The melting point of the dimethylaminoethanol salt of unresolved /3-(3,5-diiodo-4-hydroxy)-o-phenylpropionic acid was 142° to 144°C. 

D. 2,3-Diamino pyridine (Note 12). In an apparatus for catalytic hydrogenation (Note 13) 56.4 g. (0.3 mole) of 2,3-diamino-5-bromopyridine suspended in 300 ml. of 4% sodium hydroxide solution is shaken with hydrogen in the presence of 1.0 g. of 5% palladized strontium carbonate (Note 14). When absorption of hydrogen is completed, the catalyst is removed by filtration, and, after saturation with potassium carbonate (about 330 g. is required), the resulting slushy mixture is extracted continuously with ether until all the precipitate completely disappears (usually about 18 hours, but this depends on the efficiency of the extraction apparatus). The ether is removed by distillation, and the residue of crude 2,3-diaminopyridine is recrystallized from benzene (about 600 ml. is required) using 3 g. of activated charcoal and filtering rapidly through a preheated Buchner funnel. The yield of 2,3-diaminopyridine, obtained as colorless needles, m.p. 115-116°, pKa 6.84, is 25.5-28.0 g. (78-86%) (Note 15). 

Though yellow-colored, the 2-methylproline thus obtained is spectroscopically pure (according to the 1H and 1 C NMR spectra, see Note 17). It Can be further purified by dissolution in methanol with 5% w/w activated charcoal and filtration ot the resulting suspension through Celite. In spite of the poor crystallizing tendency of most amino acids, 2-methylproline can be recrystallized from... 

Kasei Kogyi Co., Ltd and Eastman Kodak Co., respectively). These products were purified by repeated recrystallization from acetone and treatment with active charcoal. Cj PyBr was synthesized by reacting the corresponding alkylbromide (Eastman Kodak), purified by fractional distillation, with a slight excess of pyridine (30). The crude product was purified by extraction with diethylether, followed by up to 6 recrystallizations from acetone and treatment with active charcoal. 

Of the above product, 18.3 g (30 mmol) is carefully ground and suspended in acetone (95 mL). The snspension is vigoronsly stirred at -15°C while Cu powder (11.5 g, 180 mmol) is added over 40 min (the temperature must not exceed - 10°C). The mixtnre is stirred for a farther 20 min and is then allowed to warm at 20°C. The dark-colonred mixtnre is filtered to remove CuCl, the filter cake is washed with acetone and the filtrate and washings are combined. The acetone solntion is warmed at 20°C until a grey precipitate forms. The precipitate is collected and extracted repeatedly with boiling toluene. Activated charcoal is added to the tolnene extracts, the mixtnre is heated at reflux and filtered and most of the toluene is distilled from the filtrate. Petrolenm ether is added to precipitate the prodnct (p-MeOCgH4)2TeCl2, which is recrystallized from benzene (6.8 g (52%) m.p. 182°C). 

Telluraxanthene Bis(2-bromophenyl)methane (3.33 g, 1.02 mmol) is dissolved in 300 tuL of absolute diethyl ether and, under dry nitrogen, 22 mL (36.1 mmol) of a 15% solution of n-butyllithium in hexane are added dropwise. The mixture is heated under reflux for 0.5 h, cooled to 20°C and 1.8 g (14.1 mmol) of finely powdered tellurium are added. The resultant mixture is heated under reflux for 2 h and then poured into ice/water. The mixture is extracted with chloroform, the extract is filtered and the solvent is evaporated in a rotatory evaporator at 20°C under aspirator vacuum. The residue is recrystallized from diethyl ether/petroleum ether after addition of activated charcoal. Yield 1.42 g (47%) m.p. 151°C. 

The precipitation of protodolomite under 100°C. from solutions of calcium and magnesium chlorides has been reported, and it seems plausible to suggest that, given sufficient time, dolomite would result from recrystallization of protodolomite. Siegel (35) found that protodolomite was produced at 25 °C. when calcium and magnesium ions were entrapped in activated charcoal and could react with carbonate ion at a low rate he also found that sulfate ion was involved in dolomite formation. 

A mixture of 4 parts of 2-iminothiazoline, 8.3 parts of bromomethyl-2-thienylketone and 40 parts of absolute ethanol is stirred and refluxed for 2 hours in a water-bath. After cooling, the precipitated hydrobromide is filtered off. From this salt the free base is liberated on treating with ammonium hydroxide solution and it is extracted with chloroform. The organic extract is separated, treated with activated charcoal, filtered and the filtrate is first dried over magnesium sulfate and then evaporated. The solid residue is recrystallized from 24 parts 2-propanol, to yield 2-imino-3-[(2-thienylearbonyl)-methyl]-thiazoline MP 117.5°-118.5°C. 

The oily residue is dissolved in 480 parts of anhydrous diisopropyl ether. This solution is boiled with activated charcoal, filtered and to the clear filtrate is added an excess of 2-propanol, previously saturated with gaseous hydrogen chloride. The precipitated salt is filtered off and recrystallized from a mixture of 2-propanol and ethanol, yielding l-cinnamyl-4-(di-p-fluorobenzhydryl) piperazine dihydrochloride, MP 251.5°C. 

The mixture was then poured into water and acidified with hydrochloric acid. The organic material was extracted with chloroform, the chloroform was exaporated, and the residue stirred for one and 1.5 h with dilute potassium hydroxide solution. Acetic acid was added to make the solution almost neutral, but still slightly basic, the mixture was stirred with activated charcoal for about 15 min, filtered, and the filtrate acidified to Congo red with hydrochloric acid. A crystalline product was obtained upon cooling for several hours, and this was collected by filtration and recrystallized from water giving a-ethyl-m-hydroxycinnamic acid. 

Oxo-2,3-dihydro-4//-benzotelIurin3 27.6 g (9.3 mmol) of 2-carboxyethyl phenyl tellurium and 15.6 g (10 mmol) of butyl dichloromethyl ether are heated in the presence ofzinc(II) chloride at 50°. After evolution of hydrogen chloride has ceased, 100 m/ of carbon tetrachloride and activated charcoal are added. The resultant mixture is filtered, the solvent is evaporated from the filtrate on a water bath, and the residue is dissolved in 150 ml of dichloromethane. The solution is cooled to — 70° and 15 g (12 mmol) of aluminum trichloride are added in small portions to the cold solution. The mixture is allowed to warm to — 5 over 30 min, hydrolyzed with ice/water, and extracted with diethyl ether. The ether layer is separated, washed with aqueous sodium carbonate solution, dried, and the solvent is evaporated. The residue is distilled under vacuum and the fraction boiling at 150°/0.8 torr is collected. The product is recrystallized from methanol yield 1.45 g (60%) m.p. 34°. 

Dimethylaminophenyl 4-Fluorophenyl Tellnrinm Dichloride2 In a 250 ml flask fitted with a reflux condenser are placed 16.5 g (50 mmol) of 4-fluorophenyl tellurium trichloride, 19.0 g (50 mmol) of 4-dimcthylaminophenyl mercury acetate, and 100 ml of absolute dioxane. The mixture is heated under reflux for 8 h during which time it acquires a dark violet color. The mixture is allowed to cool to 20°, the precipitated mercury(II) chloride/dioxane adduct is filtered off, and activated charcoal is added to the filtrate which is then heated under reflux for 30 min. The mixture is allowed to cool and is then passed through a layer of aluminum oxide. The filtrate is concentrated to one-fourth of its original volume by distillation, the concentrate is diluted with 100 ml of hexane to precipitate the product which is filtered off, washed with hexane, dried, and recrystallized from propanol yield 7.2 g (35%) m.p. 145". 

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