Solution, sulfuric acid preparation

One of the separatory funnels is filled with 1 1. of sulfuric acid prepared by the careful addition of 392 g. (4 moles) (213 cc.) of concentrated sulfuric acid to 213 cc. of water. The other separatory funnel is filled with a solution of 203 g. of commercial sodium cyanide (about 96 per cent) (4 moles) dissolved in sufficient water to make 500 cc. of solution. Evolution of hydrogen cyanide takes place on the simultaneous addition of the two solutions. Practically all of the reaction occurs in the funnel, F, and the sodium bisulfate solution continuously drains into the flask so that fresh solutions are always present. The solution in the funnel remains clear as long as sufficient sulfuric acid is present. An excess of sodium cyanide colors the solution yellow and leads to the formation of a muddy brown precipitate. By adjusting the flow of solutions the rate of evolution is easily controlled, and the preparation requires no attention beyond that involved in the occasional replenishment of the solutions in the separatory funnels. The last part of the hydrogen cyanide can be driven from the apparatus by boiling the bisulfate solution for a few minutes. The yield of acid melting at — r5° to — r4.5° is roo-ro5 g. (93-97 per cent of the theoretical amount) (Notes 3 and 4). 

Wear nitrile rubber gloves, laboratory coat, and eye protection. Avoid breathing dust. Cover spill with a 1 1 1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand. Scoop mixture into a container of water. Add 3 M sulfuric acid (prepared by cautiously adding 10 mL of concentrated acid to 50 mL of cold water) to neutralize the solution, and then add a further 20 mL for each 1 g of dichromate (to give a pH of 1). While stirring, add sodium thiosulfate crystals until the solution becomes blue colored and cloudy (approximately 10 g/g dichromate). Slowly and cautiously neutralize the solution with sodium carbonate (approximately 3.2 g/mL of 3 M... 

Wear eye protection, laboratory coat, and rubber gloves. Dissolve the aniline (1 mL) in 50 mL of 3 M sulfuric acid (prepared by slowly adding 8 mL of concentrated sulfuric acid to 21 mL of water). Weigh 10 g of potassium permanganate and stir small portions of the solid into the aniline solution over a period of about 1 hour. Stir the mixture at room temperature for 48 hours, and then neutralize the solution by adding solid sodium carbonate or a 10% solution of sodium hydroxide. Add solid sodium bisulfite until solution is colorless. Decant the clear liquid into the drain and discard any brown solid with regular refuse.11,12... 

Small Quantities. To each 5 mL of benzaldehyde to be discarded, add 6 g of potassium permanganate in 100 mL of 3 M sulfuric acid (prepared by adding 17 mL of concentrated sulfuric acid to 83 mL of water). Stir the mixture overnight. Add solid sodium bisulfite until the solution is clear a small quantity of brown precipitate may remain. Neutralize the liquid with 5% aqueous sodium hydroxide and wash into the drain. Discard any brown solid with normal refuse.7... 

To each 9 mg of benzidine, add 10 mL of 0.1 M hydrochloric acid (prepared by slowly adding 1 mL of concentrated acid to 119 mL of cold water). Mix to dissolve. Add 5 mL of 0.2 M potassium permanganate solution (0.3 g of solid potassium permanganate dissolved in 10 mL of water) and 5 mL of 2.0 M sulfuric acid (prepared by carefully adding 1 mL of concentrated acid to 8 mL of cold water). Mix and let stand overnight (at least 10 hours). Decolorize, if necessary, with sodium metabisulfite or ascorbic acid. Neutralize by careful addition of 5 M sodium hydroxide solution (20 g of NaOH dissolved in 100 mL of cold water). Wash the remaining solution into the drain.7... 

Solid. Cover the area of the spill with a 0.3 M solution of potassium permanganate in 3 M sulfuric acid (prepared as for solution spills). Allow to stand overnight. Absorb the liquid residue on a 1 1 1 mixture by weight of soda ash, clay cat litter (bentonite), and sand. Scoop the solid into a container and, in the fume hood, add to a beaker of cold water. If necessary, neutralize the solution by the cautious addition of soda ash. Decant the liquid into the drain with water. Treat the solid as normal refuse.4,5... 

Small Quantities (Red Phosphorus). Add the red phosphorus (5 g) to a solution of potassium chlorate (33 g) in 2 L of 1 N sulfuric acid (prepared by cautiously adding 56 mL of concentrated acid to 1944 mL of cold water) in a 3-L, three-necked, round-bottom flask equipped with water-cooled condenser and heating mantle. Heat the mixture under reflux until all of the phosphorus has dissolved (5-10 hours). When the solution has cooled to room temperature, reduce the excess chlorate by adding about 14 g of sodium bisulfite. Wash the solution into the drain.33... 

Small Quantities. Wear nitrile rubber gloves, eye protection, laboratory coat, and respirator (or work in hood). The selenium salt is dissolved in water and the solution is neutralized by the addition of 1 M NaOH (prepared by dissolving 4 g of NaOH in 100 mL of water) or 1 M sulfuric acid (prepared by cautiously adding 5 mL of concentrated acid to 85 mL of cold water). A 1 M solution of sodium sulfide (prepared by dissolving 7.8 g of Na2S in 100 mL of water) is added to the selenium salt solution and the pH is again adjusted to neutral with 1 M sulfuric acid solution. The precipitate is separated by filtration or decantation. Wash, dry, and recycle or send for disposal in a secure landfill.1 ... 

Wear eye protection, laboratory coat, and nitrile rubber gloves. Prepare a 10% aqueous solution of the waste sodium chlorate. For each 10 mL of solution, slowly, and while stirring, add 44 mL of a 10% solution of sodium bisulfite (this allows about 50% excess of reducing agent). The continued presence of chlorate can be detected by adding, to 3 mL of the solution, a freshly prepared solution of potassium iodide (100 mg) in 3 mL of 3 M sulfuric acid (prepared by cautiously adding 0.5 mL of concentrated acid to 2.5 mL of cold water). An amber to brown color indicates the presence of chlorate. Add sodium bisulfite solution until the test is negative. Neutralize the acidic solution with sodium carbonate and discard into the drain with at least 50 times its volume of water.11 12... 

The residue is cooled to 40° and slowly hydrolyzed (cooling as necessary) with 900 cc. of cold 6 N sulfuric acid, prepared from 145 cc. of concentrated sulfuric acid and 700 cc. of water. The oily layer is separated, washed once with water, and distilled at 60-70° while the pressure is lowered slowly from about 275 mm. to 65 mm. Finally the distillation is continued to 100° and 20 mm. This procedure permits separation of all the crotyl alcohol from the higher-boiling polymerization products. The aqueous layers are combined and distilled until the distillate no longer gives a test for unsaturation with a dilute solution of bromine in carbon tetrachloride. The distillate is then saturated with potassium carbonate, and the oily layer which separates is added to the product obtained by distillation of the oil. 

If concentrated sulfuric acid has a concentration of 17.8 mol dm, calculate the concentration of 500 cm3 of a solution of sulfuric acid prepared by diluting 25 cm3 of the concentrated acid. 

Caprolactam is obtained at atmospheric pressure, in the presence of a solvent (cyclohexane) in a multistage reactor. Hexahydrobenzoic add and oleum, previously mixed at 35 C, are introduced into the reactor. Nitrosyl sulfuric acid (prepared by the absorption of NO—NO in oleum) is injected at each stage in predetermined quantities. Once-through conversion of hexahydrobenzoic add is limited to 50 per cent The temperature is kept at 80 C by the evaporation of cyclohexane. The reactor effluent is then diluted with water at low temperature. The cyclohexane evaporated is recondensed and used to extract unconverted hexahydrobenzoic add and allow its recycle, while the caprolactam formed goes into the aqueous solution. This phase is neutralized by ammonia. Ammonium sulfate, formed at the rate of 4.2 t/t of product, is recovered by centrifuging. The lactam is extracted with the toluene, reextracted with water and dehydrated. The final yield of the operation is 72 per cent weight in relation to toluene. 

The decomposition may be effected by cautious warming in a round-bottomed flask under an air-condenser, in a wide hard-glass tube, or even in an evaporating dish. The last of these techniques was used for preparation of 1-, 2-, and 3-chlorophenanthrene, and for the corresponding bromo compounds,1241 the amines having been diazotized at 0° by nitrosyl-sulfuric acid (prepared from NaN02 and a 2 1 mixture of concentrated H2S04 and water) to which pyridine solutions of the bases were added. 

Sample preparation 10 mL Urine + 2 mL 1 M HCl (check pH is 1-2), heat 37° for 3 h, add 5 mL pH 6.5 phosphate buffer, add 2 mL 1 M NaOH (check pH is 6.5-7.0). Add to a 20 cm Extrelut SPE column, rinse flask with 3 mL water, add rinsings to column, dry for 15 min, elute with 40 mL dichloromethane, evaporate eluent to dryness, dry over concentrated sulfuric acid. Prepare a 100 mg/mL solution of 4-nitrobenzoyl chloride (4-NBP) in dry pyridine with gentle heating. Use immediately. Dissolve residue from colunm in 30 p,L dry pyridine, add 20 p,L 2 mg/mL digitoxigenin in pyridine, add 300 p.L 4-NBP solution, shake well. Heat at 70° for 1 h, add 2 mL 5% sodium bicarbonate, shake until precipitate has dissolved, add 2 mL chloroform, shake, centrifuge, repeat extraction twice. Combine chloroform layers, wash three times with 2 mL 1 M HCl, inject an ediquot of chloroform solution directly. 

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