Calcium sulfate solvent

Graded Adsorbents and Solvents. Materials used in columns for adsorption chromatography are grouped in Table 12 in an approximate order of effectiveness. Other adsorbents sometimes used include barium carbonate, calcium sulfate, calcium phosphate, charcoal (usually mixed with Kieselguhr or other form of diatomaceous earth, for example, the filter aid Celite) and cellulose. The alumina can be prepared in several grades of activity (see below). 

Calcium sulfate (anhydrous). (Prepared by heating the dihydrate or the hemihydrate in an oven at 235° for 2-3h it can be regenerated.) Available commercially as Drierite. It forms the hemihydrate, 2CaS04.H20, so that its capacity is fairly low (6.6% of its weight of water), and hence is best used on partially dried substances. It is very efficient (being comparable with phosphorus pentoxide and concentrated sulfuric acid). Suitable for most organic compounds. Solvents boiling below 100° can be dried by direct distillation from calcium sulfate. 

The checkers distilled the anisole from calcium sulfate before use. This reagent functions not only as a reactant, but also as solvent. In some similar preparations the intermediate trichloride is rather insoluble, as in the case of bis(3-methyl-4-methoxyphenyl)tellurium dichloride. The addition of co-solvents such as bis-(2-methoxyethyl) ether is beneficial. ... 

Calcium sulfate cannot be removed by HC1. Suitable solvents include neutralized (pH 6.5) tetrasodium EDTA at 200 to 300 °F, together with ammonium carbonate EDTA/organic acids... 

After the addition of acid chloride, about 25 ml of methylene chloride was used to rinse the residual acid chloride into the flask. The mixture was stirred for about 3 h. The pH was then adjusted to between 9.5 and 10 and the solution was stirred for an additional hour. The organic layer was separated from the aqueous layer and washed once with 5% NaOH solution. The solution was dried over calcium sulfate and the methylene chloride was evaporated leaving about 10.36 g (69%) of crude product. Decolorizing three times with Attapulgus clay yielded a light yellow brown methylene chloride solution which, on removal of solvent, gave about 5.2 g of product (35%). 

Prayon One of the Wet processes for making phosphoric acid by reacting phosphate rock with sulfuric acid. The byproduct is gypsum, calcium sulfate dihydrate. It uses a compartmentalized, multi-section, lined, concrete reactor, with finishing tanks in which the gypsum crystals mature. In 1990 one third of the wet process phosphoric acid made in the Western World was made in this way. The process was developed in 1977 by the Societe de Prayon, Belgium. Variations are known as PH2, PHI 1, and PH12. One variation uses solvent extraction with isopropyl ether and tri-n-butyl phosphate. 

MOLECULAR SIEVE INCIDENTS ethylene ORGANIC POWDER HANDLING PEROXIDES IN SOLVENTS SOLVATED OXOSALT INCIDENTS Cadmium propionate, 2418 Calcium acetylide Methanol Diazomethane Calcium sulfate, 0406 3,5 -Dinitrotoluamide... 

Sulfuric acid has found limited use in boiler cleaning operations. It is not feasible for removal of hardness scales due to the formation of highly insoluble calcium sulfate. It has found some use in cases where a high-strength, low-chloride solvent is necessary. Use of sulfuric acid requires high water usage in order to rinse the boiler sufficiently. 

The insoluble calcium sulfate slurry is filtered out. Acid from this wet process is impure but can be purified by various methods. Purification steps involve precipitation, solvent extraction, crystallization, and ion exchange techniques. 

Commercial acrolein (Shell Chemical Corp.) was distilled and shaken with an equal volume of anhydrous calcium sulfate for 30 minutes. The acrolein (containing an impurity of 3.5% of propionaldehyde) was distilled again just before use (b.p., 52.5—52.9° C.). Oxidation products identified using acrolein (99.9% purity) without propionaldehyde, which was removed by the Tischenko reaction (31). Solvents were used after purification (especially dehydration) by conventional methods. 

Developments of recent years include plants designed to precipitate the calcium sulfate in the form of the hemihydrate instead of gypsum, hi special cases, hydrochloric acid is used instead of sulfuric acid for rock digestion, the phosphoric acid being recovered in quite pure form by solvent extraction. Solvent-extraction methods have also been developed for the purification of merchant-grade acid, which normally contains impurities amounting to 12 18% of the phosphoric acid content. Processes for recovering part of the fluorine in the phosphate rock are in commercial use. 

Ionic solids contain ions held together by ionic bonds. These solids are typically hard and have high melting points. They are often soluble in water, but insoluble in organic solvents. They do not conduct electricity in the solid state, but do so both in aqueous solutions and in pure molten form. (Use a solid like calcium sulfate as an ionic solid, which is not soluble in water.)... 

Strelyuk described a thin-layer chromatographic method for the qualitative detection of dipyridamole [62], Data were presented on the use of various reagents for the detection by solution color change and precipitate formation in the thin-layer chromatography of dipyridamole. Thin-layer chromatography was on silica gel-calcium sulfate dihydrate, with methanol aqueous ammonia or benzene-dioxane being used as the mobile phase with detection at 270-330 nm. The Rvalues were 0.7-0.75 and 0.5-0.55 for the two solvent systems, and the detection limit was... 

A mixture of 171 g. (1 mole) of dimethyl-a-naphthylamine (Note 1) and 125 g. (1.2 moles) of cyanogen bromide 1 in a 1-1. flask (Note 2) is heated under reflux on the steam bath for 16 hours (Note 3). The cooled reaction mixture is added to 2.5 1. of dry ether, and the insoluble quaternary salt (Note 4) is filtered. The ether filtrate is extracted with four 800-ml. portions of approximately 15% hydrochloric acid solution (Note 5) and washed with five 500-ml. portions of water. The ether solution is dried with 30-35 g. of anhydrous calcium sulfate (Drierite). After filtration, the solvent is removed by distillation at atmospheric pressure on the steam bath the residue is fractionated under reduced pressure. The yield of pale yellow oil, boiling at 170-171°/ mm- (185—187°/3 mm.), amounts to 115-122 g. (63-67%) (Note 6). 

Bis[3-phcnyl-l-rf-propyl] Ditellurium1 A suspension of 266 mg (2.0 mmol) 3-phenylpropanal and 1.75 g (4.0 mmol) aluminum telluridein 10 ml tetrahydrofuran is cooled to - 78°. A solution of 0.21 m/(4.0 mmol) of concentrated (98%) sulfuric acid in 1.75 ml (96 mmol) deuterium oxide is added to the chilled suspension. The mixture is wanned to 20° and then heated to the reflux temperature with continuous stirring over a 30 min period. The mixture is then refluxed for 1.5 h. After cooling to 20°, the black precipitate is removed by filtration. The filtrate is washed with aqueous sodium hydrogen carbonate solution and dried with calcium sulfate. The mixture is filtered, the solvent removed from the filtrate, and the residue chromatographed with hexane/benzcnc (1 1) as the mobile phase. The product was obtained as a dark-red oil in 70% yield. 

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