Deposition upon cooling

If the solution contains chloride ions, it is evident that no silver or mercury(I) salt is present. When lead is present, the solution may be clear while hot, but PbCl2 is deposited upon cooling the solution, due to the slight solubility of the salt in cold water. Lead may be found in Group II, even if it is not precipitated in Group I. 

An ore is a metal-bearing mineral that is valuable enough to be mined. Ore formation is primarily due to temperature and pressure effects (e.g., magmatic concentration, deposition upon cooling, evaporation, hydrothermal processes), weathering and transport phenomena (e.g., sedimentation, metamorphism, mechanical concentration, residual concentration), and chemical processes (e.g., abiotic and biotic oxidations, and reductions). These effects, phenomena and processes are illustrated in Figures 5.2-5.4. 

The complete assembly for carrying out the catalytic decomposition of acids into ketones is shown in Fig. Ill, 72, 1. The main part of the apparatus consists of a device for dropping the acid at constant rate into a combustion tube containing the catalyst (manganous oxide deposited upon pumice) and heated electrically to about 350° the reaction products are condensed by a double surface condenser and coUected in a flask (which may be cooled in ice, if necessary) a glass bubbler at the end of the apparatus indicates the rate of decomposition (evolution of carbon dioxide). The furnace may be a commercial cylindrical furnace, about 70 cm. in length, but it is excellent practice, and certainly very much cheaper, to construct it from simple materials. 

For the hydrolysis, 36 g. (O.ll mole) of the residue is transferred to a 1-1. round-bottomed flask equipped with a reflux condenser, and 210 ml. of concentrated hydrochloric acid in 190 ml. of water is added. The mixture is refluxed gently at first, then vigorously (Note 6), until hydrolysis is essentially complete (about 20 hours). Then 180 ml. of W ater and 4 g. of Norite A are added and the mixture is stirred and boiled for 3 minutes, after which it is rapidly filtered with suction through two layers of hardened filter paper in a Buchner funnel (Note 7). The filtrate, upon cooling to 20° or below, deposits 18 g. (72%) of lightly colored 2,5-dihydroxy- -benzenediacetic acid (Note 8). A snow-... 

Scott and co-workers [79] proposed a mechanism for CNT formation that involves the initial formation of a carbon cloud consisting of short carbon entities ( 3) and vaporized catalyst. Upon cooling, the condensation of the catalyst hinders the aggregation of carbon blocks into larger clusters, while supporting the anisotropic addition of carbon units into SWCNTs instead. The deposited SWCNTs are then collected from the cooled chamber walls after the synthesis. 

N-Phenylhydroxylamine (11 g., 0.10 mole)2 (Note 1) and N-phenylmaleimide (17.4 g., 0.10 mole)3 are suspended in 40 ml. of ethanol contained in a 200-ml. Erlenmeyer flask. To the mixture is added immediately (Note 2) 8.98 g. (11.2 ml., 0.124 mole) of freshly distilled w-butyraldehyde. An exothermic reaction ensues, and the mixture spontaneously heats to the boiling point. A clear slightly yellow solution results which, upon cooling, deposits an almost colorless crystalline cake. The mixture is allowed to stand in the ice box for 1 day it is then filtered through a Buchner funnel, and the crystals are washed twice with 25-ml. portions of ice-cold ethanol. The yield of air-dried product, m.p. 99-101°, is 31-32 g. (92-95%). For further purification the crude material is dissolved in 60 ml. of boiling ethanol on the steam bath, and the resulting solution is allowed to cool slowly to room temperature. If crystallization does not spontaneously begin in 5-10 minutes, it can then be induced by... 

SYNTHESIS In 50 mL of benzene there was dissolved 31.6 g 2,5-dimethoxy-4-methylbenzaldehyde (see recipe for 2C-D for its preparation), 20.2 mL 1-nitropropane, and 6 mL cyclohexylamine. This solution was held at reflux in a Dean Stark apparatus for 24 h, effectively removing the water of reaction. Upon cooling, there was deposited 19.6 g of 1 -(2,5-dimethoxy-4-methylphenyl)-2-nitro-1 -butene as brilliant orange crystals. The mp, after recrystallization from MeOH, was 114-115 °C and a second recrystallization increased the mp another 2 °C. Anal. 

However, the majority of sodium sulfate is now obtained directly from natural salt sources. Brines with 7 to 11% sodium sulfate are used and pumped through a salt deposit to lower the solubility of the sodium sulfate so that, upon cooling, the decahydrate (Glauber s salt) will crystallize and can be separated. Heating then forms the anhydrous salt cake. 

Boron trifluoride-diethyl ether (7.1 g, 0.05 mol) is added during 5 min to the previously prepared solution of (IV-methylanilino)lithium. The pale-yellow slurry is then refluxed for 3 hr. At the end of this time, the mixed solvent is concentrated to approximately one-half of its original volume by distillation from the reaction vessel. The reaction mixture is cooled to 0° and subjected to a vacuum filtration through a 9-cm Buchner funnel to afford 22.0 g of a tan precipitate. This solid is placed in 200 mL of toluene, which is then brought to a boil the mixture is subjected to a hot vacuum-filtration in order to remove the lithium fluoride co-product. A considerable reduction in yield may result unless a steam-jacketed Buchner funnel or hot sintered-glass filter is used. Upon cooling, the toluene filtrate deposits white crystals, which are collected by filtration. Yield 13.7 g (83%) of tris(N-methyl-anilino)borane, mp 211-213° (lit. mp 210° 1 214-216°3). ... 

In this technique, a wax-like material, which is solid at room temperature, is melted and deposited by inkjet onto a substrate. The wax solidifies upon cooling, before a new layer of liquid wax is deposited. Support constructions are built in the same way as model construction layers and use the same material. 

Triphenylamine (125 g) was dissolved in 5 L ethyl alcohol, HgO (150g) added at 60°C, followed by (100 g), and the reaction refluxed 2 hours. Thereafter, the mixture was hot filtered, the residue washed with acetone, and upon cooling, crystals deposited. The crystals were purified by chromatography using silica gel with toluene and 52 g product isolated. 

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