Residual liquors

Upon cooling and filtering, there is obtained 2 g of 5jff-androstane-3a,6a,17 -triol-3,6-dinitrate 17-acetate mp 130-131°. Chromatography of the mother liquor residue over alumina yields an additional 0.4 g mp 134-135°. Total yield 68%. 

The first crop of the product contains only a trace of the 20 -epimer. The main portion of this compound is found in the mother liquor. Use of the material of a second crop for the subsequent steps is not recommended. The residue of the mother liquor can, however, be reoxidized to pregnenolone acetate by the method described in step C. By crystallization of the oxidation product of the mother liquor residue from methanol, 13-14 g. of pure pregnenolone acetate can be recovered. 

The zinc content of EAF dust can be removed by sulphating, using iron sulfate derived from a waste product in some steelmaking processes, pickle liquor residue, as the main... 

Benzonitrile (1.520g, 14.8mmol) was added to the THF solution of the sodium salt generated from (1) (1.830g, 14.8 mmol) by the action of sodium hydride (1.24 eq) at room temperature, and the resulting solution was stirred at 50°C for 16h. After addition of water (2 ml) together with dichloromethane (70 ml), the mixture was dried over anhydrous sodium sulfate (without separation of the aqueous layer) and the solid phase was filtered off. Evaporation of the filtrate under reduced pressure and subsequent crystallization from dichloromethane/carbon tetrachloride/ cyclohexane (1 1 1) afforded (2) as a crystalline material (2.391 g, 10.5 mmol), m.p. 162-163°C (105 mg of (2) could be recovered by chromatography on silica gel of the mother liquor residue of evaporation the total yield of (2) was 75%). 

Tall oil is the generic name for the oil obtained upon acidification of the black liquor residue from kraft pulp digesters. Kraft processing dissolves the fats, fatty acids, rosin, and rosin acids contained in pinewoods in the form of sodium salts and when the black liquor is concentrated to make it possible to recover some of its chemical and heating value, the soaps become insoluble and can be skimmed off. The brown, frothy curd thus obtained is then made acidic with sulfuric acid, converting the constituents to a dark-brown fluid (tall oil). 

The apparatus depicted in Fig. 11,34, 1, intended for advanced students, may be used for the filtration of a small quantity of crystals suspended in a solvent either a Hirsch funnel or a glass funnel with Witt filter plate is employed. The mixture of crystals and mother liquor is filtered as usual through the funnel with suction. Rotation of the three-way tap wifi allow air to enter the filter cylinder, thus permitting the mother liquor to be drawn oflF by opening the lower tap. The mother liquor can then be applied for rinsing out the residual crystals in the vessel, and the mixture is again filtered into the cylinder. When all the crystals have been transferred to the funnel and thoroughly drained, the mother liquor may be transferred to another vessel the crystals may then be washed as already described (Section 11,32). 

A further 25 g. of cyanoacetamide may be obtained by evaporating the original mother liquor to dryness under reduced pressure (water pump) whilst heating the flask on a steam bath. The residue is dissolved in 50 ml. of hot ethanol, the solution shaken for a few minutes with decolourising carbon, Altered with suction whilst hot, and then cooled in ice. The resulting yellowish amide is recrystallised with the addition of decolourising carbon, if necessary. 

Mix together in a 250 ml. flask carrying a reflux condenser and a calcium chloride drying tube 25 g. (32 ml.) of freshly-distilled acetaldehyde with a solution of 59-5 g. of dry, powdered malonic acid (Section 111,157) in 67 g. (68-5 ml.) of dry pyridine to which 0-5 ml. of piperidine has been added. Leave in an ice chest or refrigerator for 24 hours. Warm the mixture on a steam bath until the evolution of carbon dioxide ceases. Cool in ice, add 60 ml. of 1 1 sulphuric acid (by volume) and leave in the ice bath for 3-4 hours. Collect the crude crotonic acid (ca. 27 g.) which has separated by suction filtration. Extract the mother liquor with three 25 ml. portions of ether, dry the ethereal extract, and evaporate the ether the residual crude acid weighs 6 g. Recrystallise from light petroleum, b.p. 60-80° the yield of erude crotonic acid, m.p. 72°, is 20 g. 

Cautiously add 250 g. (136 ml.) of concentrated sulphuric acid in a thin stream and with stirring to 400 ml. of water contained in a 1 litre bolt-head or three-necked flask, and then dissolve 150 g. of sodium nitrate in the diluted acid. Cool in a bath of ice or iced water. Melt 94 g. of phenol with 20 ml. of water, and add this from a separatory funnel to the stirred mixture in the flask at such a rate that the temperature does not rise above 20°. Continue the stirring for a further 2 hours after all the phenol has been added. Pour oflF the mother liquid from the resinous mixture of nitro compounds. Melt the residue with 500 ml. of water, shake and allow the contents of the flask to settle. Pour oflF the wash liquor and repeat the washing at least two or three times to ensure the complete removal of any residual acid. Steam distil the mixture (Fig. II, 40, 1 or Fig. II, 41, 1) until no more o-nitrophenol passes over if the latter tends to solidify in the condenser, turn oflF the cooling water temporarily. Collect the distillate in cold water, filter at the pump, and drain thoroughly. Dry upon filter paper in the air. The yield of o-nitrophenol, m.p. 46° (1), is 50 g. 

Mix 42 5 g. of acetone cyanohydrin (Section 111,75) and 75 g. of freshly powdered ammonium carbonate in a small beaker, warm the mixture on a water bath FUME CUPBOARD) and stir with a thermometer. Gentle action commences at 50° and continues during about 3 hours at 70-80°. To complete the reaction, raise the temperature to 90° and maintain it at this point until the mixture is quiescent (ca. 30 minutes). The colourless (or pale yellow) residue solidifies on coohng. Dissolve it in 60 ml. of hot water, digest with a little decolourising carbon, and filter rapidly through a pre-heated Buchner funnel. Evaporate the filtrate on a hot plate until crystals appear on the surface of the liquid, and then cool in ice. Filter off the white crystals with suction, drain well, and then wash twice with 4 ml. portions of ether this crop of crystals of dimethylhydantoin is almost pure and melts at 176°. Concentrate the mother liquor to the crj staUisation point, cool in ice, and collect the... 

A further small quantity may be recovered from the mother liquors by removing the solvent at atmospheric pressure and distilling the residue under reduced pressure the anhydride passes over at 184-186°/ 8 mm. 

Additional operations essential to commercial bauxite processing are steam and power generation, heat recovery to minimise energy consumption, process liquor evaporation to maintain a water balance, impurity removal from process liquor streams, classification and washing of ttihydrate, lime caustication of sodium carbonate [497-19-8] to sodium hydroxide [1310-73-2] repair and maintenance of equipment, rehabiUtation of mine and residue disposal sites, and quaUty and process control. Each operation in the process can be carried out in a variety of ways depending upon bauxite properties and optimum economic tradeoffs. 

Black Liquor Soap Recovery. Black Hquor soap consists of the sodium salts of the resin and fatty acids with small amounts of unsaponifiables. The soap is most easily separated from the black Hquor by skimming at an intermediate stage, when the black Hquor is evaporated to 25% soHds (7). At this soHds level, the soap rises in the skimmer at a rate of 0.76 m/h. At higher soHds concentrations, the tall oil soap is less soluble, but higher viscosity lowers the soap rise rate and increases the necessary residence times in the soap skimmer beyond 3—4 hours. The time required for soap recovery can be reduced by installing baffles, by the use of chemical flocculants (8,9), and by air injection into the suction side of the soap skimmer feed pump. Soap density is controUed by the rate of air injection. Optimum results (70% skimmer efficiency) are obtained at a soap density of 0.84 kg/L (7 lb/gal). This soap has a minimum residual black Hquor content of 15% (10—12). 

Cycloocta l,5-dlona-2 -(or 3 )earboxyllc acid mattiyl aster (3) (4), A solution d eyclohe)(a-1,3-dlone 1 (1.00 g, 8.9 mmol) in methyl acrylate 2 (100 g. 1.16 mmol) was Irradiated with a X 450 W medkjm pressure lamp under Na through a pyrex (Iter (or 5 h. The semicrystalliM residue obtained after removal oi the solvent, was crystallized from MeOH, the n ther liquor, separated by preparative TLC (PhH Et20) and the main fraction oonMned vrilh the crystals to gM 1.06 g of 3 (60%), mp 104-105°C (MeOH), The second minor fraction (from TLC) gave 4, mp 91 C (MeOH). 

A further quantity can be recovered by concentrating the mother liquor. The residue of decolorizing carbon is also likely to contain an appreciable proportion of trimethylgallic acid, which can be extracted by boiling it with the mother liquor. 

The alcohol may be distilled from the mother liquor of the recrystallization. The residue from this distillation may be added to the mother liquor of the first crystallization, which is then concentrated to the crystallization point. The crop of crystals thus obtained will usually require double recrystallization. Alcohol recovered from the first mother liquor will contain too much volatile oil of nutmeg to be used for other purposes. 

This material Is purified by recrystallization from ethyl acetate acetone 2 1 (v v) to give a first crop (6.8 g), and by flash chromatography of the residue from the mother liquor, using 150 g of 230-400 mesh silica gel (Merck), a 40-mm diameter column, and elution with 10 1 (v v) ethyl acetate methanol. A fast moving orange band and a slower moving lemon-yellow band can be clearly seen on the column. The lemon-yellow hand is collected from the column and evaporation gives a second crop (1.4 g) of comparably pure material. The total yield of the pale yellow isoquinoline is 8.2 g (86t), mp 135-137°C (Note 10). 

The successive crops of crystals are systematically recrystallized as follows, using Norite if necessary. About two-thirds of the first crop is dissolved in about three parts of water and the hot solution allowed to deposit crystals by slow cooling (Note 3). The liquor is filtered or decanted, the remainder of the first crop is dissolved in it, and the process of crystallization is repeated. The remaining crops are then similarly recrystallized in succession from the same liquor, the solution being evaporated to the appropriate volume before each crystallization. The final mother liquor is evaporated in stages and the viscous residue is united with that from the original crystallization. The various crops are systematically recrystallized from fresh water until pure... 

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