Atmosphere moisture precipitation

Treatment of liquid air (containing condensed atmospheric moisture) with fluorine give a potentially explosive precipitate, thought to be fluorine hydrate [1], Contact of liquid fluorine with a bulk of water causes violent explosions. Ice tends to react explosively with fluorine gas after an indeterminate induction period [2],... 

A one-liter flask fltted with a stirrer, reflux condenser and separatory flask is charged with 7.6 g (0.2 mol) of lithium aluminum hydride and 500 ml of anhydrous ether. A solution of 44.4 g (0.6 mol) of anhydrous terr-butyl alcohol in 250 ml of ether is added slowly from the separatory funnel to the stirred contents of the flask. (The hydrogen evolved is vented to a hood.) During the addition of the last third of the alcohol a white precipitate is formed. The solvent is decanted and the flask is evacuated with heating on the steam bath to remove the residual ether and tert-butyl alcohol. The solid residue - lithium tri-/er/-butoxyaluminohydride - is stored in bottles protected from atmospheric moisture. Solutions 0.2 m in reagent are prepared by dissolving the solid in diglyme. 

In an apparatus suitably protected against atmospheric moisture and carbon dioxide, to a solution of 4.0 gm (0.0164 mole) of 2,2 -dinitrobiphenyl in 35 ml of anhydrous benzene is cautiously added, with stirring, a solution of 3.0 gm (0.08 mole) of lithium aluminum hydride in 15 ml of anhydrous ether. The mixture is heated to reflux for 4 hr, during which time a brown precipitate forms. After the reaction mixture has been cooled, 5 ml of water is cautiously added and the... 

If desired, the salt may be purified as follows The solid is rapidly dissolved below 10°C in five times its weight of 2% aqueous sodium sulfide containing 1ml of 2N sodium hydroxide. The crystals are washed with 100ml of ice-cold 1 1 alcohol-water, followed by 95% alcohol and by acetone the product is briefly air-dried. An equal volume of ice-cold 95% alcohol is added during the cooling. After standing in ice until precipitation is complete (about 10 minutes), the salt is immediately suction-filtered and washed, first with cold 50% alcohol, then with 95% alcohol, followed by ether. The colorless crystals are dried briefly in air and preserved in a tightly stoppered bottle to prevent hydrolysis due to atmospheric moisture. 

The net result of evaporative isotopic fractionation of lake water is a water mass that is not in isotopic equilibrium with its water sources. Therefore, the isotopic composition of a lake water should plot below the LM WL, as shown in Figure 2. The line that passes through the isotopic composition of a lake water and its volume-weighted input from precipitation and ground-water is referred to as an evaporation line. This line represents the isotopic evolution of lake water from its source waters. The slope of an evaporation line is a function of humidity, temperature, and the isotopic composition of atmospheric moisture above the lake the slope generally ranges from about 3.5 to 6.0 (23). 

Tungsten(VI) tetrabromide oxide is a dark-brown crystalline compound, which is obtained in the form of needles or flakes. It is extremely sensitive to atmospheric moisture, decomposes rapidly in water, which leaves a gray-green precipitate, and is completely dissolved in solutions of ammonia or sodium hydroxide, which form clear, colorless solutions. It is slightly soluble in concentrated hydrochloric acid, dioxane (yellow solution), 2-methoxyethanol (colorless solution), and acetone (green solution). It has a melting point of 322°C., as determined by D.T.A. 

Samples of mesoporous titanium dioxide were synthesized via sol-gel hydrolysis of Ti(IV) tetrabutoxide in 1-butanol by atmospheric moisture in the presence of a structure-directing template dibenzo-18-crown-6 ether. After completion of the sol-gel transformation and ageing of the precipitate, the mother liquor with the precipitate was exposed to hydrothermal treatment (HTT) at 100 - 175 °C for 24 h. Then, the precipitate was separated, dried, and calcinated on air at 350 - 500 °C for 4 hours. 

Dibenzylidene-l,3-ditelluretane1- 3 Under an inert atmosphere, 1.15 g (50 mmol) of sodium are dissolved in 250 ml of liquid ammonia (freshly distilled from sodium). A small amount of iron(III) nitrate is added to the ammonia solution and then 5.1 g (50 mmol) of phenylacetylene are added dropwise to the stirred sodium amide solution over 30 min. The mixture is allowed to stand for 30 min, 6.4 g (50 mmol) of finely powdered tellurium are added, and the ammonia is evaporated from the mixture under protection against atmospheric moisture. Residual liquids are evaporated under vacuum. The residue (sodium phenylethyneteUuiolate) is dissolved in 50 ml of absolute dimethyl sulfoxide and the solution is cooled to 0°. Under continuous cooling, 25 ml of a 2 molar solution of hydrogen chloride in diethyl ether is added slowly. The precipitate is filtered off, washed with water, chloroform, and then recrystallized from dimethylformamide to give the trans-isomer yield 4.3 g (38%) m.p. 270-275°. 

In addition to the obvious preparative advantages inherent in the pentachloride preparation, e.g., the low temperature of reaction and the possibility of performing the reaction without precautions against atmospheric moisture because of the protection afforded by thionyl chloride, the product is obtained free from oxide chloride. The major losses occur during the hydrous oxide precipitation and the nitric acid washings. The latter are essential to remove adsorbed ammonium ion, since, if this is not done, the reaction products will be niobium (V) chloride, in solution in thionyl chloride, and the bright yellow insoluble ammonium hexachloroniobate(V). In fact, the high purity of these two products in instances where complete removal of ammonium ion is not achieved shows clearly that the reaction of hydrous niobium (V) oxide with thionyl chloride is virtually quantitative. 

Trimethoxyarsine (dj 1.4264 ng 1.4402) is a colorless liquid which is readily hydrolyzed by atmospheric moisture, forming a white precipitate of arsenic trioxide. The compound is soluble in carbon tetrachloride, benzene, chloroform, hydrocarbons, and ethers. The product is shown to be at least 99.5% pure (with respect to hydrogen-containing impurities) by proton nuclear magnetic resonance (n.m.r.), since a single sharp peak at —3.52 p.p.m. (relative to internal tetramethylsilane) is seen in the n.m.r. spectrum of the neat liquid. Similar properties are shown by triethoxyarsine (d 1.2132 ng 1.4360) and tri- i-butoxyarsine (dj 1.0723 nj 1.4476). 

The weight of an ignited precipitate is itself not necessarily represented accurately by the balance reading there may be equilibration of the precipitate and container with atmospheric moisture (the atmosphere in a desiccator probably is not dry), and absorption of carbon dioxide or ammonia. 

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