Supernatant liquid

Now fit the weighed funnel G again to the filter-flask, and attach the Pregl filter-tube K as shown (Fig. 21). Apply 2i gentle suction from the water-pump, and dip the open limb of the tube K just below the surface of the liquid in the Carius tube. Draw off the supernatant liquid a little at a time until rather less than 1 ml. remains. Now gently shake the mixture in the Carius tube, and try to adjust the suction so... 

Urease solution. Place about 5 g. of jack-bean meal in a mortar and grind up with about 10 ml. of water, t hen add about 90 ml. of water, mix thoroughly and allow to stand for some time in order to deposit starch and other insoluble substances. Decant off the supernatant liquid into a conical flask and cork the latter. 

Cuprous chloride. Hydrated copper sulphate (125 g.) and sodium chloride (32-5 g.) are dissolved in water (400 ml.) boiling may be necessary. An allialine solution of sodium sulphite (from 26 5 g. of sodium bisulphite and 17 -5 g. of sodium hydroxide in 200 ml. of water) or the solution of the sodium bisulphite alone is added to the resulting hot solution during about 5 minutes with constant shaking. The solution will be decolourised or nearly so. It is then cooled to room temperature (or in an ice bath), and the supernatant liquid is decanted... 

The palladium - barium sulphate catalyst Is prepared by treating a suspension of20g. of barium sulphate (which has been precipitated in hot solution) in 400 ml. of hot water with a solution of I - 7 g. of palladium chloride (equivalent to I - 0 g. of palladium) in 50 ml. of water and with I - 5 ml. of 40 per cent, formaldehyde solution. The mixture is rendered faintly alkaline to litmus by the addition of sodium hydroxide solution and then boiled for a short time. When the supernatant liquid is clear, the grey precipitate is filtered oS, and wa.shed with hot water until the... 

Beckmann rearrangement of benzophenone oxime to benz-anilide. Dissolve 2 g. of benzophenone oxime in 20 ml. of anhydrous ether in a small conical flask and add 3 g. of powdered phosphorus pentachloride (or 3 ml. of pure tbionyl chloride). Distil off the solvent and other volatile products on a water bath CAUTION ether), add 25 ml. of water, boil for several minutes and break up any lumps which may be formed. Decant the supernatant liquid, and recrystallise, in the same vessel, from boiling alcohol. The product is benzanilide, m.p. 163° confirm this by a mixed m.p. determination with an authentic specimen. 

The number of washings may be reduced to about twenty, if time is allowed for diffusion of the alkali from the surface of the catalyst into the surrounding wash water. Use 750 ml. of water in each washing, allow diffusion to proceed for 3-10 minutes, stir again, and decant the supernatant liquid as soon as the catalyst settles to the bottom. 

Preparation of palladium - calcium carbonate catalyst. Prepare 60 g. of precipitated calcium carbonate by mixing hot solutions of the appropriate quantities of A.R. calcium chloride and A.R. sodium carbonate. Suspend the calcium carbonate in water and add a solution containing 1 g. of palladium chloride. Warm the suspension until all the palladium is precipitated as the hydroxide upon the calcium carbonate, i.e., until the supernatant liquid is colourless. Wash several times with... 

Solubility in water. Treat a 0 10 g. portion of the solid with successive 10 ml. portions of water, shaking vigorously after each addition, until 3 0 ml. have been added. If the compound does not dissolve completely in 3 0 ml. of water, it may be regarded as insoluble in water. When dealing with a liquid, add 0 -20 ml. of the compound to 3 0 ml. of water and shake. In either case, test the contents of the small test-tube with htmus (or with Universal indicator paper) it is best to remove a little of the solution or supernatant liquid with a dropper. 

Solubility in 5 per cent, sodium hydroxide solution. Note whether there is any rise in temperature. If the compound appears insoluble, remove some of the supernatant liquid by means of a dropper to a semimicro test-tube (75 X 10 mm.), add 5 per cent, hydrochloric acid dropwise until acid, and note whether any precipitate (or turbidity) is formed. The production of the latter will place the compound in Group III. 

Murexide Indicator. Suspend 0.5 g of powdered murexide in water, shake thoroughly, and allow the undissolved solid to settle. Use 5-6 drops of the supernatant liquid for each titration. Decant the old supernatant liquid daily and treat the residue with water to provide a fresh solution of the indicator. 

Crystd from hot water (4mL/g at 65°), then dried in a vacuum desiccator over CaS04. Phillips and Taylor [J Chem Soc 4242 7962] cooled an aqueous solution of KMn04, saturated at 60°, to room temperature in the dark, and filtered through a No.4 porosity sintered-glass filter funnel. The solution was allowed to evaporate in air in the dark for 12h, and the supernatant liquid was decanted from the crystals, which were dried as quickly as possible with filter paper. 

In a 250-ml. three-necked flask, fitted with a mechanical stirrer, a reflux condenser, and an inlet for admission of nitrogen, is placed 100 ml. of tetrahydrofuran (Note 1). With stirring, 27.1 g. (0.166 mole) of anhydrous ferric chloride is added in portions, followed by 4.7 g. (0.084 gram atom) of iron powder (Note 2). The mixture is heated with stirring under nitrogen at the reflux temperature for 4.5 hours, giving a gray powder with a brown supernatant liquid. 

Commercial tetrahydrofuran (Matheson, Coleman and Bell) is washed several times with 40% aqueous sodium hydroxide to remove peroxides and organic stabilizers and then dried over solid sodium hydroxide. The clear supernatant liquid is used without further purification. 

Locate the time when the upper interface (between the supernatant liquid and slurry) is at height Z g, halfway between the initial height, Zg, and the extrapolated zero-time compression zone height, Z g. This time represents the period in which all the solids were at the critical dilution and went into compression. The retention time is computed as t -1,., where t is the time when the solids reach the specified... 

Zinc powder (32.8 g,0.5 moles) is washed successively with hydrochloric acid (3%, 4 X 25 ml), distilled water (4 x 30 ml), aqueous copper sulfate (2%, 2 X 50 ml), distilled water (4 x 30 ml), absolute ethanol (4 x 30 ml) and absolute ether (5 x 25 ml). The washings are performed conveniently by stirring a mixture of the zinc powder and each wash solution with a porcelain spatula in an open beaker and then decanting the supernatant liquid. The couple is finally transferred to a Buchner funnel, washed with additional anhydrous ether, and then vacuum-dried in a round-bottom flask. 

The usual means of identifying and quantifying the level of these additives in polymer samples is performed by dissolution of the polymer in a solvent, followed by precipitation of the material. The additives in turn remain in the Supernatant liquid. The different solubilites of the additives, high reactivity, low stability, low concentrations and possible co-precipitation with the polymer may pose problems and lead to inconclusive results. Another sample pretreatment method is the use of Soxhlet extraction and reconcentration before analysis, although this method is very time consuming, and is still limited by solubility dependence. Other approaches include the use of supercritical fluids to extract the additives from the polymer and Subsequent analysis of the extracts by microcolumn LC (2). 

When the entire quantity of the phosphoric acid has thus been added, agitation of the mixture is continued for about a half-hour or more to insure complete conversion. The precipitate is then allowed to settle, the supernatant liquid is drawn off, and the residue is filtered. The precipitate thus separated may, if desired, be washed with acetone and is then dried by evaporation to constant weight. It forms a fine, white, impalpable powder consisting of pure monobasic amphetamine phosphate. 

The contents of the tube were then acidified to pH 2 by the addition of sulfuric acid and centrifuged. Examination of the supernatant liquid by paper chromatography employing the methods of 8ohonos et al. Antibiotics Annual (1953-4, page 49), demonstrates the presence of 7-chloro-6-demethyltetracycline, 7-chlorotetracycline and tetracycline. 

The product separates as a gum from which the supernatant liquid is decanted, and the gum is triturated with 250 cc of water in order to induce crystallization. The crude product thus obtained is recrystallized from 3,200 cc of boiling water and then from 40% aqueous isopropyl alcohol yielding 4,5-dichlorobenzene-1,3-disulfonamide as a white solid, MP 228.5° to 229.0°C. 

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