Solid water crystallization

Dimethylaminomethylindole (gramine). Cool 42 5 ml. of aqueous methylamine solution (5 2N ca. 25 per cent, w/v) contained in an 100 ml. flask in an ice bath, add 30 g. of cold acetic acid, followed by 17 -2 g. of cold, 37 per cent, aqueous formaldehyde solution. Pour the solution on to 23 -4 g. of indole use 10 ml. of water to rinse out the flask. Allow the mixture to warm up to room temperature, with occasional shaking as the indole dissolves. Keep the solution at 30-40° overnight and then pour it, with vigorous stirring, into a solution of 40 g. of potassium hydroxide in 300 ml. of water crystals separate. Cool in an ice bath for 2 hours, collect the crystalline solid by suction flltration, wash with three 50 ml. portions of cold water, and dry to constant weight at 50°. The yield of gramine is 34 g. this is quite suitable for conversion into 3-indoleacetic acid. The pure compound may be obtained by recrystaUisation from acetone-hexane m.p. 133-134°. 

In spite of their easy interconversion in solution a and p forms of carbohydrates are capable of independent existence and many have been isolated m pure form as crys talline solids When crystallized from ethanol d glucose yields a d glucopyranose mp 146°C [a]o +112 2° Crystallization from a water-ethanol mixture produces p d glucopyranose mp 148-155°C [aj +18 7° In the solid state the two forms do not mterconvert and are stable indefinitely Their structures have been unambiguously con firmed by X ray crystallography... 

In spite of theii easy interconversion in solution, a and p fonns of carbohydrates are capable of independent existence, and many have been isolated in pure fonn as crystalline solids. When crystallized from ethanol, D-glucose yields a-D-glucopyianose, mp 146°C, [a]o -1-112.2°. Crystallization from a water-ethanol mixture produces P-d-glucopyranose, mp 148-155°C, +18.7°. In the solid state the two fonns do not... 

Random and structured packings are susceptible to surface fouling due to process conditions and/or the presence of oxygen as may be related to bacterial growth. Some systems will precipitate solids or crystals from solution usually due to the temperature and concentration effects. Bravo [135] discusses air-water stripping and illus-... 

Snow is normally defined as precipitation formed of ice crystals and ice as solid water with hexagonal structure and density about 920 kg m-3. In snow storage the main issue is to have enough amounts of frozen water at low cost why the only relevant distinction is the density. If natural snow or ice is too expensive or not available in enough quantity, it is possible to produce frozen water. Artificial snow and ice made with different types of water sprayers, including snow blowers (snow guns). The production rate depends on equipment, relative air humidity, and temperatures of the air and water. 

The outer potential, ip, depends on the electric charge on the condensed phase, but the surface potential, x> is usually assumed to be characteristic of individual condensed phases. For noncharged condensed phases, the outer potential is zero (ip = 0) and the inner potential becomes equal to the surface potential. The magnitude of x is + 0.13 V for liquid water [Trasatti, 1980] and is in the range of +0.1 to+5.0 V for solid metal crystals [Trasatti, 1974]. 

White crystalline solid prismatic crystal faint odor of ammonia stable at ambient temperature but decomposes on heating at 60°C melts at 107.5°C on very rapid heating density 1.586 g/cm vapor pressure 435 torr at 25°C readily dissolves in water (21.6g/100g at 20°C, and 36.6g/100g at 40°C). 

Colorless crystalline solid cubic crystal unstable density 1.02 g/cm decomposes at 36°C sublimes at 40°C very soluble in cold water and alcohol decomposes in hot water. 

White crystalline solid orthorhombic crystal density 1.769 g/cm at 20°C melts between 511 to 515°C (in a closed system) however, in an open system, it melts with decomposition at 280°C readily dissolves in water (solubility, 70.6 g and 104 g per 100 g water at 0°C and 100° C, respectively) insoluble in acetone, alcohol and ether. 

Colorless crystalline solid orthorhombic crystal hygroscopic density 3.14 g/cm3 melts at 73.4°C boils at 220.3°C readily dissolves in water undergoing hydrolysis soluble in dilute hydrochloric acid, ethanol, acetone, benzene, diox-ane and CS2. 

Soft crystalline solid rhombic crystal pure salt is white but color may vary the color of the mineral barite may vary among red, yellow, gray or green depending on impurities density 4.50 g/cm refractive index 1.64 melts around 1,580°C decomposes above 1,600°C hardness 4.3 to 4.6 Mohs insoluble in water (285 mg/L at 30°C) and alcohol Ksp 1.1 x 10-i° soluble in concentrated sulfuric acid. 

Colorless crystalline solid tetragonal crystal system hygroscopic density 2.50 g/cm3 (tetrahydrate 1.71 g/cm ) tetrahydrated salt loses water of crystallization on heating further heating to 550°C causes decomposition soluble in water, tetrahydrate more soluble in water (30.5g/100g at 30°) than the anhydrous salt insoluble in alcohol. 

Natural malachite is a dark green crystalline solid monoclinic crystals density 4.0 g/cm refractive index 1.655 decomposes at 200°C insoluble in cold water and alcohols decomposes in hot water soluble in acids, ammonium hydroxide and potassium cyanide solutions. 

White crystalline solid cubic crystals density 0.82 g/cm melts at 686.4°C decomposes in water soluble in acids. 

The monohydrate MnS04 H20 consists of red monochnic crystals density 2.95 g/cm3 highly soluble in water. The tetrahydrate MnS04 4H20 is a pink solid monochnic crystals density 2.107 g/cm highly soluble in water more soluble than the anhydrous salt or the monohydrate. 

The hexahydrate is a yellow crystalline solid orthogonal crystals density 2.81 g/cm3 hygroscopic melts at 60°C decomposes at 118°C very soluble in water soluble in alcohol and ether. 

The hydrated salt, ZnF2 4H20, is a white crystalline solid rhombohedral crystals density 2.30 g/cm loses water of crystallization at 100°C sparingly... 

Boric acid is a white solid that crystallizes from water as waxy platelets. The crystal structure of boric acid consists of triangular B(0H)3 molecules interconnected by hydrogen bonding into planar layers 3.18 A apart, (Fig. 20) [88]. 

Purification is accomplished by crystallization from a solution prepared from the crude product and 100 mL of water at a maximum temperature of 50°. (The time at this temperature should be kept minimal.) Filtration of the nearly saturated solution through coarse fiber-glass paper (Whatman GF/A) removes impurities of low solubility. At 0° the solid product crystallizes slowly 12 hours are required for complete deposition. The orange solid is collected on a filter and dried under atmospheric conditions (not vacuum). Yield 17.0 g, 66% of theory. Water of hydration is lost under low humidity conditions or under vacuum. Anal. Calcd. for Na6V10O2g 18H2O V, 35.89 H20, 22.84. Found V, 35.51 H20, 22.65%. 

The vapour deposition method is widely used to obtain amorphous solids. In this technique, atoms, molecules or ions of the substance (in dilute vapour phase) are deposited on to a substrate maintained at a low temperature. Most vapour-deposited amorphous materials crystallize on heating, but some of them exhibit an intervening second-order transition (akin to the glass transition). Amorphous solid water and methanol show such transitions. The structural features of vapour-deposited amorphous solids are comparable to those of glasses of the same materials prepared by melt-quenching. 

B. Diphenaldehydic acid. A mixture of 10 g. (0.0368 mole) of 3,8-dimethoxy-4,5,6,7-dibenzo-l,2-dioxacyclooctane, 50 ml. of 10% sodium hydroxide solution, and 200 ml. of 95% ethyl alcohol is heated under reflux for 15 minutes, during which time the solid dissolves (Note 3). The solution is cooled, acidified with concentrated hydrochloric acid, and diluted to the cloud point with water. Crystallization is induced by rubbing the side of the vessel with a stirring rod (Note 4). More water is then added slowly until crystallization is complete. Filtration yields 6.7-7.3... 

In freeze drying, upon water crystallization, the non-frozen solution is viscous and the diffusion of flavors is retarded. Upon beginning of freeze drying, the surface of this solution becomes an amorphous solid in which selective diffusion comes into play. 

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