Amorphous powders

A mixture of polymethylene glycols of the type (CH20) ,xH20 where n is 6- 50. It is a white, amorphous powder having the odour of meth-anal, m.p. I20-130°C. The commercial product contains 95% methanal and is obtained in while flocculent masses when solutions of methanal are evaporated or allowed to stand. When heated it is converted to methanal. Used as a convenient solid substitute for methanal. 

The boron so obtained is an amorphous powder. It can be obtained in the crystalline state by reducing the vapour of boron tribromide with hydrogen, either in an electric arc or in contact with an electrically-heated tungsten filament ... 

Sucralfate. Sucralfate [54182-58-0] (Carafate) (6) is a white amorphous powder soluble in dilute hydrochloric acid and sodium hydroxide. It is practically insoluble in water, ethanol, and carbon tetrachloride. Dissolution of aluminum occurs at pH <3. It may be prepared by the method described in Reference 7. 

Purified hGH is a white amorphous powder in its lyophilized form. It is readily soluble (concentrations >10 mg/mL) in dilute aqueous buffers at pH values above 7.2. The isoelectric point is 5.2 (3) and the generally accepted value for the extinction coefficient at 280 nm is 17,700 (Af-cm) (4),... 

Iron(II) hydroxide [18624-44-7], Fe(OH)2, is prepared by precipitation of an iron(II) salt solution by strong base in the absence of air. It occurs as pale green, hexagonal crystals or a white amorphous powder. It is practically insoluble in water, fairly soluble in ammonium salt solutions, and soluble in acids and in concentrated NaOH solution. It is slowly oxidized by air. Conversion to Fe203 atH20 is eventually complete. 

Mercurous Iodide. Mercurous iodide [7783-30 ] Hg2l2, is a bright yellow amorphous powder, extremely insoluble in water and very sensitive to light. It has no commercial importance but may be prepared by precipitation, using mercurous nirate and potassium iodide. Care must be taken to exclude mercuric nitrate, which may cause the formulation of the water-insoluble mercuric iodide. 

Using rapid solidification technology molten metal is quench cast at a cooling rate up to 10 °C/s as a continuous ribbon. This ribbon is subsequently pulverized to an amorphous powder. RST powders include aluminum alloys, nickel-based superalloys, and nanoscale powders. RST conditions can also exist in powder atomization. 

Structure and Crystallinity. The mechanical—optical properties of polycarbonates are those common to amorphous polymers. The polymer may be crystallized to some degree by prolonged heating at elevated temperature (8 d at 180°C) (16), or by immersion ia acetone (qv). Powdered amorphous powder appears to dissolve partially ia acetone, initially becoming sticky, then hardening and becoming much less soluble as it crystallizes. Enhanced crystallization of polycarbonate can also be caused by the presence of sodium phenoxide end groups (17). 

Tungsten dichlofide [13470-12-7], WCI2, is an amorphous powder. It is a cluster compound and maybe prepared by the reduction of the hexachloride with aluminum in a sodium tetrachloroalurninate melt (11). 

The physical properties of elemental boron are significantly affected by purity and crystal form. In addition to being an amorphous powder, boron has four crystalline forms a-rhombohedral, P-rhombohedral, a-tetragonal, and -tetragonal. The a-rhombohedral form has mp 2180°C, sublimes at approximately 3650°C, and has a density of 2.45 g/mL. Amorphous boron, by comparison, has mp 2300°C, sublimes at approximately 2550°C, and has a density of 2.35 g/mL. 

Cobalt(II) phosphate octahydrate [10294-50-5], Co2(P0272 8H20, is a red to purple amorphous powder. The product is obtained by reaction of an alkaline phosphate and solutions of cobalt salts. The material is insoluble in water or alkaU, but dissolves in mineral acids. The phosphate is used in glazes, enamels, pigments (qv) and plastic resins, and in certain steel (qv) phosphating operations (see Enamels,PORCELAIN ORVITREOUS). 

Alumina—A white, odorless, tasteless, amorphous powder consisting essentially of aluminum hydroxide, AI2O2 xH20 (see Aluminum compounds, ALUMINUM oxide). 

Dihydrostreptomycin sesquisulfate [5490-27-7] M 461.4, m 250 (dec), 255-265 (dec), [a]p -92.4 (c 1, H2O), pKgsJd)-- 9.5 (NMe), pKes,(2,3) 13.4 (guanidino). It crystallises from H2O with MeOH, -BuOH or methyl ethyl ketone. The crystals are not hygroscopic like the amorphous powder, however both forms are soluble in H2O but the amorphous solid is about 10 times more soluble than the crystals. The free base also crystallises from H20-Me2C0 and has [a]p -92° (aqueous solution pH 7.0). [Solomons and Regina Science 109 515 7949 Wolf et al. Science 109 515 7949 McGilveray and Rinehart J Am Chem Soc 87 4003 1956]. 

In order to obtain pure title substance, the acid 8 is suspended in 150 ml of methanol and treated while stirring with 10 ml of a 2N solution of the sodium salt of 2-ethylcaproic acid in ethyl acetate. After about 10 minutes, there results a solution which is treated with 100 ml of ethanol. The mixture is extensively concentrated at 40°C in vacuo. The sodium salt precipitates out in amorphous form after adding ethanol. This salt is filtered off under suction, washed successively with ethanol and low-boiling petroleum ether and dried at 40°C in a high vacuum. There is obtained the title substance in the form of an almost colorless amorphous powder. 

Preparation of Alkaloid III Tannate 20 g of Alkaloid III was dissolved in 200 ml of isopropyl alcohol at room temperature and a mixture of 30 g of tannic acid dissolved in 300 ml of isopropyl alcohol, maintained at 40 to 50 C was added thereto with rapid stirring. The mixture was cooled to 20 C, filtered and the precipitate dried at about 80 C. There was thus obtained 33.5 g of the tannate salt of Alkaloid III, as a pale yellow amorphous powder, relatively insoluble in water, and having an indefinite melting point. 

A sample of 4 parts is recrystallized from a boiling mixture of 80 parts isopropanol, 40 parts methanol and 500 parts water. The whole is filtered and after cooling the filtrate overnight at -20°C, 1-benzyl4-(2,6-dioxo-3-pheny -3-piperidyl)-piperidine hydrochloride is obtained, melting point 299°C to 301,5°C, as a white amorphous powder. 

A solution of the amide chloride (4.6 g) in dry, alcohol-free chloroform (20 ml) was added slowly to a solution of trimethylsilyl 6-amino-penicillanate (7.2 g) and triethylamine (3.5 ml) in dry, alcohol-free chloroform (50 ml) with stirring and cooling to -70°C. The temperature was raised to 0°C during 1V4 hours. The solution was evaporated to dryness in vacua and the residue was triturated with dry ether (200 ml). The precipitate was filtered off and washed with dry ether. The filtrate was diluted with ether (200 ml). 2-Butanol (2.8 ml) was added dropwise with stirring and cooling to0°C. The stirring was continued for A hour at 0°C, whereupon the precipitate was filtered off, washed with ether and dried. It was a white, amorphous powder, soluble in water. 

The column was then eluted with 0.0025N sulfuric acid in methanol-water mixture (1 1 v/v). A total of 900 ml of fractions containing a substance which showed UV absorption at 290 m/u was collected. After removal of methanol by distillation, the residual liquid was adjusted to pH 6.0 with Dowex 44 (OH type) and freeze-dried to obtain 9.3 g (95% yield) of NK631 monosulfate (copper-free form) in the form of pale yellowish-white amorphous powder. 

Bj Pivaloyloxymethyl D(—)-Ot-aminobenzylpenicillinate. hydrochloride To a solution of pivaloyloxymethyl D(—)-a-azidobenzylpenicillinate (prepared as described above) in ethyl acetate (75 ml) a 0.2 M phosphate buffer (pH 2.2) (75 ml) and 10% palladium on carbon catalyst (4 g) were added, and the mixture was shaken in a hydrogen atmosphere for 2 hours at room temperature. The catalyst was filtered off, washed with ethyl acetate (25 ml) and phosphate buffer (25 ml), and the phases of the filtrate were separated. The aqueous phase was washed with ether, neutralized (pH 6.5 to 7.0) with aqueoussodium bicarbonate, and extracted with ethyl acetate (2 X 75 ml). To the combined extracts, water (75 ml) was added, and the pH adjusted to 25 with 1 N hydrochloric acid. The aqueous layer was separated, the organic phase extracted with water (25 ml), and the combined extracts were washed with ether, and freeze-dried. The desired compound was obtained as a colorless, amorphous powder. 

In the case of tantalum-containing solutions, a sharp drop in Ta205 concentration was observed also at pH > 10. The precipitated material was identified as a pure amorphous powder, which after appropriate thermal treatment was converted into tantalum oxide. Fig. 137 presents isotherms (20°C) of Ta205 concentration versus pH for solutions with compositions close to those of industrial strip solutions. 

Ethylnitrolic acid is an expl compd and forms numerous metallic salts, some of which are expls Potassium Salt. KC2H303N2, colorl amorph powder, si sol in methanol a weak expl Silver Salt. AgC2H303N2) white amorph powder, insol in w and dil ale. Sensitive to light,... 

Nitrostarch can be prepared by dissolving starch in an excess of nitric acid and pouring this solution into an excess of sulfuric acid to precipitate NS as an amorphous powder. This method is uneconomical and hard to control. Consequently it is not used commercially... 

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