Crystallization decolorization

Research has shown that ascorbic acid can be produced from hulls of immature walnuts by extracting the hull with 0.2% sulfur dioxide solutions, and purifyiag the extract by adsorption on and elution from anion-exchange resias (see Ion exchange). Eluates from the anion-exchange step are concentrated, purified by organic solvent fractionations, decolorized, and crystallized (35). 

C), the yield of more than 90% purity L-glutamic acid crystals is very high. The glutamic acid crystals appear as both the metastable a- and stable P-forms. The a-form consists of prismatic crystals which are easy to filter, whereas the P-form needle crystals are difficult to filter. Control of crystallisation conditions of a-crystals are requited (13). The cmde L-glutamic acid crystals are suspended ia water and neutralized with caustic soda or sodium hydroxide. The solution is decolorized with activated carbon to produce a transparent solution and MSG is crystallized under reduced pressure. 

If the material is not partly dried before hydrolysis, the yield of the hydrochloride is diminished because of its solubility. If pure 3-bromo-4-acetaminotoluene is desired, the crude material may be crystallized from 50 per cent alcohol with the addition of decolorizing carbon (Norite) as almost colorless needles, m.p. 116-117°, The yield is 360 g, (79 per cent of the theoretical amount). This purification has no advantage when the acetam-ino compound is to be hydrolyzed to the amine. 

In a 500-cc. round-bottom flask fitted with a reflux condenser are placed 68 g. of phenylurea (0.5 mole) (Note i) and 120 cc. (i mole) of 42 per cent hydrazine hydrate solution (Note 2). The flask is heated on a steam bath for about twelve hours. The hot mixture is treated with a small amount of decolorizing charcoal (Norite) and filtered. The charcoal is washed with two 15-CC. portions of warm water and the filtrate and washings are then concentrated on a steam bath to about 100 cc. On coolipg in an ice bath a crop of crystals separates and is collected on a filter and washed with two 15-cc. portions of cold water. The filtrate and washings are concentrated to about 25 cc. and another crop of crystals is obtained as before. The total yield of crude compound is 47-52 g. It is white at first but sometimes turns brown on drying. It usually melts below 115° because of some unchanged phenylurea. 

In order to secure a pure product the above material is dissolved in 175 cc. of tetrachloroethane by boiling and the solution is boiled under reflux for fifteen minutes with 12 g. of decolorizing carbon, and then filtered by suction into an Erlenmeyer flask, washing the charcoal with about 50 cc. of hot solvent. The filtrate is kept hot, treated with 750 cc. of boiling alcohol, and set aside to crystallize. The benzanthrone separates as pure yellow needles melting at r7o-i7r° yield, 48-52 g. (60-65 per cent of the theoretical amount) (Note 7). 

To 40 g. of dry chitin in a 500-ml. beaker is added 200 ml. of concentrated hydrochloric acid (c.p., sp. gr. 1.18), and the mixture is heated on a boiling water bath for 2.5 hours with continuous mechanical agitation. At the end of this time solution is complete, and 200 ml. of water and 4 g. of Norite are added. The beaker is transferred to a hot plate, and the solution is maintained at a temperature of about 60° and is stirred continuously during the process of decolorization. After an hour the solution is filtered through a layer of a filter aid such as Filter-Cel. The filtrate is usually a pale straw color however, if an excessive color persists, the decolorization may be repeated until the solution becomes almost colorless. The filtrate is concentrated under diminished pressure at 50° until the volume of the solution is 10-15 ml. The white crystals of glucosamine hydrochloride are... 

The alcoholic filtrate is evaporated to 50 cc., and 50 g. of barium hydroxide and 150 cc. of distilled water are added (Note 4). The mixture is refluxed for two hours and the excess barium hydroxide is precipitated with carbon dioxide. The barium carbonate is removed by filtration and washed with hot distilled water. A slight excess of sulfuric acid is added to the filtrate to liberate the amino acid from its barium salt, and an excess of barium carbonate is added to remove sulfate ion. The mixture is digested on the steam bath until effervescence ceases, and it is then filtered and the precipitate is washed with hot distilled water. The filtrate and washings are concentrated on the steam bath to a volume of 100 cc., decolorized with i g. of active carbon, filtered, and concentrated to the point of crystallization (about 25 cc.). The amino acid is precipitated by the addition of 150 cc. of absolute alcohol and the product is collected and washed with absolute alcohol. 

Although this material is suitable for most purposes, it may be purified further in the following manner. It is dissolved by heating in a solution of 2 g. of stannous chloride and 2 cc. of concentrated hydrochloric acid in i 1. of water, and the hot solution is clarified by filtration through a 5-mm. mat of decolorizing carbon (Note g). The yellow or red color which may develop disappears on reheating to the boiling point. After the addition of 100 cc. of concentrated hydrochloric acid the solution is allowed to cool in an ice bath, treated with a second roo cc. of acid, cooled to 0°, and collected and washed as befor The ciystalline product is colorless, ash-free, and of analytical purity. The loss in the crystallization of an 80-g. lot amounts to 5-10 g. (6-12 per cent). 

Gram negative Bacteria cells which lose the crystal violet during the decolorizing step and are then colored by the counterstain. Pseudomonas and Thiobacillus are examples of gram negative strains. 

In a 500-ml round-bottom flask is placed a mixture of 25 g (0.178 mole) of dimedone, 21.8 g (0,22 mole, 25 % excess) of pulverized maleic anhydride, 0.1 g of /7-toluenesulfuric acid, and 150 ml of isopropenyl acetate. The mixture is refluxed for 72 hours, then cooled, and the acetone is removed at room temperature on a rotary evaporator. The resulting solution is cooled to —20° in a Dry Ice bath, whereupon the product crystallizes. It is collected by filtration to yield the crude product in about 80% yield. Recrystallization from hexane-ethyl acetate and decolorization by Norit gives colorless crystals, mp 164-166°. 

However the acid is prepared, the sodium salt may be prepared as described in U.S. Patent 3,503,967 Five liters of methylene chloride were added to a clean dry vessel equipped with stirrer. 7-[a(4-pyridylthio)acetamido] cephalosporanic acid (1,000 g) was added to the vessel, followed by 350 ml of triethylamine. The resultant solution was treated with decolorizing charcoal for 15 minutes and filtered. A solution of sodium-3-ethyl-hexanoate (27.3%) in butanol-methylene chloride was added to the filtrate with stirring. Seven thousand five hundred milliliters of acetone was added. Crystallization occurred while stirring was continued several hours under dry conditions. The crystals were collected by filtration, washed with large volumes of acetone, and then dried in vacuo at 50°C to yield about 950 g of the title compound. 

The reaction mixture is evaporated to a small volume, whereupon the d-tubocurarine dimethyl ether iodide precipitates. The precipitate is filtered off and dissolved in boiling water. The hot solution is treated with a small amount of decolorizing carbon, the carbon filtered off and the filtrate cooled to about 0°C. The dimethyl ether of d-tubocurarine iodide crystallizes in white crystals which melt at about 267°-270°C with decomposition. 

A solution of 23.7 grams of 2-bromoacetamido-2 -fluorobenzophenone in tetrahydrofuran (100 cc) was added to liquid ammonia (approximately 500 cc) and allowed to evaporate overnight. The residue was treated with water (1 liter) and the crystals filtered off and refluxed in toluene (100 cc) for 30 minutes. The mixture was treated with decolorizing carbon (Norite) and filtered over Hyflo. The solution was concentrated to a small volume (25 cc) cooled, diluted with 20 cc of ether and allowed to stand. The product was re-crystallized from acetone/hexane to give 5-(2-fluorophenyl)3H-1,4-benzodiazepin-2(1 H)-one as white needles melting at 180° to 181°C. 

The inosine-containing solution, which was obtained by separating the cells from the resulting fermentation liquid, was treated with both decolorizing resins and anion exchange resins by means of a conventional method and then acetone was added to crystallize the inosine. 1.47 g of the crude crystals of inosine were obtained from 3.5 liters of the culture liquid containing 1 g of inosine per liter. 

Hydroxycyclopentyl-(o-chlorophenyl)-ketone N-methylimine (2.0 g) Is dissolved in 15 ml of Decalin and refluxed for Th hours. After evaporation of the Decalin under reduced pressure, the residue is extracted with dilute hydrochloric acid, the solution treated with decolorizing charcoal, and the resulting acidic solution is made basic. The liberated product, 2-methylamino-2-(o-chlorophenyl)-cyclohexanone, after crystallization from pentane-ether, has MP 92° to 93°C. The hydrochloride of this compound has MP 262° to 263°C. 

The mixture was cooled to 7°C, extracted with two 500-oc portions of ice water to remove pyridine hydrochloride, and the benzene solution of 3-o-methoxyphenoxy-2-hy-droxypropyl chlorocarbonate was added to 500 ml of cold concentrated ammonium hydroxide. The mixture was vigorously stirred at 5°C for 6 hours, then the crude white precipitate of 3-o-methoxyphenoxy-2-hydroxypropyl carbamate was filtered off, dissolved in 1,500 ml of hot benzene and completely dried by codistillation of last traces of water with benzene, treated with decolorizing carbon and filtered while hot. On cooling 160 g of product crystallized as white needles melting at 88° to 90°C. 

A mixture of 4,4 parts of 1-chloro-3-(1-naphthoxy)-2-propano and 16 parts of isopropylamine is heated in a sealed vessel at 70° B0°C for 10 hours. The vessel is cooled and to the contents there are added 50 parts of water. The mixture is acidified with 2N hydrochloric acid, and washed with 50 parts of ether. The aqueous phase Is decolorized with carbon, and then added to 50 parts of 2N sodium hydroxide solution at 0°C, The mixture is filtered. The solid residue is washed with water, dried, and crystallized from cyclohexane. There is thus obtained 1-isopropylamino-3-(1-naphthoxy)-2-propanol, MP 96°C. 

The reaction mixture is acidified with N hydrochloric acid (200 cc) and the oil formed is extracted with methylene chloride (200 cc). The methylene chloride solution is washed with water (210 cc), treated with decolorizing charcoal (5 grams), dried over anhydrous sodium sulfate and concentrated to dryness under reduced pressure (20 mm Hg) giving an oil (77 grams) which is crystallized from methanol (300 cc) to yield methyl ethyl (7-meth-oxy-10-methyl-3-phenthiazinyl)-malonate (62.4 grams) melting at 80°-82°C. 

A 15.7 g (0.1 mol) of 2,6-dihydroxy methylpy rid in e hydrochloride are suspended in 176 ml of acetonitrile, and 20fi ml (0.15 mol) of triethylamine are added to the suspension. Thereafter 13 ml (0.22 mol) of methyl isocyanate are added dropwise to the reaction mixture at 20°C to 25°C. The reaction mixture is stirred at 20°C to 30°C for one hour, thereafter boiled for 3 hours, and finally the solvent is evaporated under reduced pressure. 35 to 40 g of a greyish, crystalline residue are obtained, which Is a mixture of 2,6-dihydroxymethylpyridine-bis-(N-methylcarbamate) and triethylamine hydrochloride. The obtained residue is dissolved in 80 ml of hot water, decolorized with 2 g of activated carbon when hot, and filtered after 30 minutes of stirring. The filtrate is cooled, the resulting crystal suspension is stirred at 0°C to 5°C for 3 hours, the solids are filtered off, and dried at 50°C to 60°C. 

The reaction mixture was then poured into 1,650 parts of hot water, the pH adjusted to 8 to 9, decolorizing charcoal was added and the whole was heated on the steam for 15 minutes. The charcoal was filtered off and the hot filtrate neutralized and cooled. The2-(sulfanilamido)-5-ethyl-1,3,4-thiadiazole was purified by repeated crystallization from boiling water. 

The total amount of the hydrochloride obtained Is stirred with 50 cc of water and the mixture is mixed with 15 cc of 45% caustic soda solution. After complete dissolution, the mixture is treated with decolorizing carbon and the filtrate is brought to a pH value of 5.5 by means of hydrochloric acid, 1 7.6 g of p-aminobenzenesulfonyl-2-amino-4,5-dimethyloxazole are obtained as colorless crystals with a melting point of 193°C to 194°C (corrected), corresponding to a yield of 65.9% calculated on the basis of the 2-amino-4,5-dimethyloxazole used. 

Preparation of 3 5-diiodo-4-(4 -hydroxyphenoxy)phenylacetic acid (diac) A solution of ethyl 3 5-diiodo-4-(4 -methoxyphenoxy)phenyl acetate (9.5 g) in acetic acid (60 ml) was heated under reflux with hydriodic acid (SG 1.7, 50 ml) and red phosphorus (0.5 g) for 1 hour. The hot solution was filtered and the filtrate concentrated at 50°C and 15 mm of mercury to above 20 ml. The residue was treated with water (70 ml) containing a little sodium thiosulfate to decolorize the product. The solid was collected by filtration and purified by the method of Harington and Pitt-Rivers [Biochem. J. (1952), Vol. 50, page 438]. Yield 8,36 g (95%). After crystallization from 70% (v/v) acetic acid it melted at 219°C. 

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