Chills concentrate

The evolution of nitrogen is not always entirely satisfactory as a test owing to the possible evolution of gaseous decomposition products of nitrous acid itself. The test may be performed as follows. To i ml. of chilled concentrated sodium nitrite solution add i ml. of dilute acetic acid. Allow any preliminary evolution of gas to subside, and then add the mixed solution to a cold aqueous solution (or suspension) of the amide note the brisk effervescence. 

Recrystallized sodium azide (12 g.) is dissolved in 50 ml. of water, and 12 ml. of carbon disulfide is added. The mixture is placed in a small flask fitted with a reflux condenser and kept at a temperature of about 40°C. for approximately 48 hours. If carbon disulfide is lost by volatilization, more is added from time to time. The resulting solution of sodium azidodithiocarbonate is filtered, chilled in an ice bath, and treated with chilled concentrated hydrochloric acid. The white, crystalline precipitate is washed twice by decantation with ice water, separated by filtration on a Buchner funnel, dried on a porous plate or between filter paper, preserved in a desiccator protected from the light, and kept at a temperature below 10°C. (In this way, azidodithiocarbonic acid may be kept for 24 to 48 hours without appreciable decomposition.)... 

One other Bk(IV) halide compound, Cs2BkCl6, has been characterized by its crystallographic properties (150). This orange compound precipitated upon dissolution of Bk(IV) hydroxide in chilled, concentrated HC1 solution containing CsCl and was found to crystallize in the Rb2MnF6-type hexagonal structure with a0 = 0.7451 and... 

Chill the concentrated solution of the amine hydrochloride in ice-water, and then cautiously with stirring add an excess of 20% aqueous sodium hydroxide solution to liberate the amine. Pour the mixture into a separating-funnel, and rinse out the flask or basin with ether into the funnel. Extract the mixture twice with ether (2 X25 ml.). Dry the united ether extracts over flake or powdered sodium hydroxide, preferably overnight. Distil the dry filtered extract from an apparatus similar to that used for the oxime when the ether has been removed, distil the amine slowly under water-pump pressure, using a capillary tube having a soda-lime guard - tube to ensure that only dry air free from carbon dioxide passes through the liquid. Collect the amine, b.p. 59-61°/12 mm. at atmospheric pressure it has b.p. 163-164°. Yield, 18 g. 

Add 4 g. of malonic acid to 4 ml. of pyridine, and then add 3 1 ml. of crotonaldehyde. Boil the mixture gently under reflux over an asbestos-covered gauze, using a small Bunsen flame, for 40 minutes and then cool it in ice-water. Meanwhile add 2 ml. of concentrated sulphuric acid carefully with shaking to 4 ml. of water, cool the diluted acid, and add it with shaking to the chilled reaction-mixture. Sorbic acid readily crystallises from the solution. Filter the sorbic acid at the pump, wash it with a small quantity of cold water and then recrystallise it from water (ca, 25 ml.). The colourless crystals, m.p. 132-133°, weigh ro-i-2 g. 

Bromo-4-aminotoluene hydrochloride. Transfer the partially dried 3-bromo-4-acetaminotoluene to a 1 5-litre round-bottomed flask, add 250 ml. of rectified spirit, and reflux on a water bath until the sohd dissolves completely. Introduce through the condenser 250 ml. of concentrated hydrochloric acid to the boihng solution and continue the refluxing for a further 3 hours. During this time crystals of 3-bromo-4-aminotoluene hydrochloride separate. Pour the hot mixture into a 1-Utre beaker and cool thoroughly. Filter the crystals of the hydrochloride at the pump through a Buchner funnel and wash rapidly with two 50 ml. portions of chilled rectified spirit. The yield of the hydrochloride is 150 g. 

Dissolve 46-5 g. (45-5 ml.) of aniUne in a mixture of 126 ml. of concentrated hydrochloric acid and 126 ml. of water contained in a 1-htre beaker. Cool to 0-5° in a bath of ice and salt, and add a solution of 36-5 g. of sodium nitrite in 75 ml. of water in small portions stir vigorously with a thermometer (1) and maintain the temperature below 10°, but preferably at about 5° by the addition of a httle crushed ice if necessary. The diazotisation is complete when a drop of the solution diluted with 3-4 drops of water gives an immediate blue colouration with potassium iodide - starch paper the test should be performed 3-4 minutes after the last addition of the nitrite solution. Prepare a solution of 76 g. of sodium fluoborate (2) in 150 ml. of water, cool, and add the chilled solution slowly to the diazonium salt solution the latter must be kept well stirred (1) and the temperature controlled so that it is below 10°. Allow to stand for 10 minutes with frequent stirring. Filter... 

Grind 25 g. of anthraniUc acid with 46 ml. of concentrated hydrochloric acid and 75 ml. of water in a glass mortar, and transfer the suspension to a 500 ml. round-bottomed flask which is provided with a mechanical stirrer. Cool the contents of the flask in an ice bath to 0-5°, and add a solution of 13-2 g. of sodium nitrite in 175 ml. of water from a dropping fimnel during about 20 minutes. Keep the diazonium solution below 6° and, if it is not clear, filter it by suction through a chilled Buchner funnel immediately before use. 

Zinc is not considered to be toxic, but when freshly formed ZnO is inhaled a disorder known as the oxide shakes or zinc chills sometimes occurs. Where zinc oxide is encountered, recommendations include providing good ventilation to avoid concentration exceeding 5 mg/ms, (time-weighted over an 8-hour exposure, 40-hour work week). 

In order to vaUdate this concept, an experiment was performed using an ice-water slurry and it was found that a 25% ice slurry had a two-to-four-times higher thermal capacity than chilled water (44). As the concentration of ice particles in the ice-slurry mixture increased up to 30%, no significant change of pressure drop was reported compared to pure water. 

Concentration of Rare Gas Crudes. The distillation of air is classically carried out in the double-column and auxihary equipment of Figure 5. Dry, C02-free air, chilled to partial liquefaction by heat exchange, is introduced into the lower nitrogen or high pressure column. This unit is typically... 

Concentrations of nickel carbonyl as low as 30 ppm in air for 30 min may be lethal for humans. Individuals exposed to these high concentrations show immediate symptoms of dizziness, headache, shortness of breath, and vomiting. These early symptoms generally disappear in fresh air, but delayed symptoms may develop 12—36 h later. These latter symptoms include shortness of breath, cyanosis, chest pain, chills, and fever. In severe exposure cases. 

The partially dried 3-bromo-4-acetaminotoluene is refluxed with 500 cc. of 95 per cent ethyl alcohol in a 3-I. round-bottom flask. To the boiling solution is added 500 cc. of concentrated hydrochloric acid and the refluxing is continued for three hours. During this time, crystals of the hydrochloride of 3-bromo-4-aminotoluene separate. The hot mixture is poured into a 2-I. beaker and cooled thoroughly in running water. The hydrochloride is filtered by suction and washed rapidly with two loo-cc. portions of chilled alcohol. The weight of the hydrochloride is 2501-300 g. (Note 4). 

The mother liquor and washings are returned to the flask and again boiled for seventy-two hours under reflux. The liquid is concentrated to 8oo cc. and again chilled to 0°, inoculated and allowed to stand at 0° for twenty-four hours. The second crop of glucoside so obtained is filtered by suction and washed with three loo-cc. portions of cold methyl alcohol. This yield is no-145 g-i nielting at i64-r65°. The mother liquor and washings are combined and concentrated to about 300 cc., chilled to 0°,... 

C. i-Melhyllhiol-yphthalamidapropane-2,2,-dicarboxylic Acid. —A solution of 25 g. (0.066 mole) of the above ester in 30 cc. of 95 per cent alcohol is heated on the steam bath in a 200-cc. round-bottomed flask, and 70 cc. of 5 A sodium hydroxide is added. The cloudy liquid is heated until a sample gives a clear solution on dilution with water this occurs after about two hours. The solution is then chilled to 0 and cautiously neutralized to Congo red with 0.2 N hydrochloric acid, whereupon 75 cc. of 5 A hydrochloric acid is slowly added, the temperature being maintained at 0°. The acid separates as colorless crystals. This separation is completed by the slow addition of 60 cc. of concentrated hydrochloric acid (sp. gr. 1.19). The product is filtered by suction and v ashed free of salt with small quantities of ice-cold water. After drying in vacuo, the yield amounts to 21.5-22 g. (95.5-98 per cent of the theoretical amount) of a product melting at 141-143°. 

Diaminoacridine sulfate (proflavin sulfate) [1811-28-5] M 516.6, m >300°(dec), Xmax 456nm. An aqueous soln, after treatment with charcoal, was concentrated, chilled overnight, filtered and the ppte was rinsed with a little diethyl ether. The ppte was dried in air, then overnight in a vacuum oven at 70°. 

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