Desiccants copper sulfate

Zinc-Copper Couple A 500-ml Erlenmeyer flask equipped for magnetic stirring is charged with a mixture of zinc powder (49.2 g, 0.75 g-atom) and hydrochloric acid (40 ml of 3 % aqueous solution). The contents of the flask are rapidly stirred for 1 minute, and the liquid is decanted. Similarly, the zinc is washed with the following three times with 40 ml of 3% hydrochloric acid solution, five times with 100 ml of distilled water, five times with 75 ml of 2 % aqueous copper sulfate solution, five times with 100 ml of distilled water, four times with 100 ml of absolute ethanol, and five times with 100 ml of absolute ether. These last ethanol and ether washes are decanted onto a Buchner funnel to prevent loss. The residue is collected by suction filtration, washed again with anhydrous ether, and dried in air. Finally, the zinc-copper couple is stored (20-24 hours) in a vacuum desiccator over phosphorous pentoxide. 

Place 200 cc. of concentrated ammonia (25 percent) and 50 cc. of water in a flask and conduct in hydrogen sulfide to saturation (closed flask). Divide the solution into two equal portions. Saturate the one with sulfur (60 g.) at 40°, filter, and add to the other half. Prepare a solution of 20 g. of crystallized copper sulfate in 200 cc. of water and add slowly and with constant shaking to the first solution until a permanent precipitate results (CuS). Filter as rapidly as possible through a large folded filter and bring the filtrate into an Erlenmeyer flask which is of a size to be nearly filled by the solution. By allowing the solution to stand, especially if cooled by ice, reddish crystals separate which should be filtered off the next day, washed with a little water and with alcohol, and dried over lime in a desiccator. To the mother liquor more copper sulfate can be added, and the process repeated. 

Five grams of copper sulfate 5-hydrate are dissolved in 20ml of water and 3.5g of dipropylenetriamine are added with stirring. Acetone is added to the blue liquid until the product has been completely precipitated as an oil the supernatant liquid should be almost colorless. The oil is repeatedly triturated with small portions of acetone in a mortar until it forms a solid it is brought onto the filter with the same solvent and washed with a little ether. While the deep blue product is still moist, it is rapidly transferred to a vacuum desiccator and pumped dry. The material is extremely deliquescent. Losses in the preparation are only mechanical. The complex sulfate gives no precipitate with solutions of iodide, dithionate, ferricyanide, or persulfate ions. In concentrated aqueous medium, however, the addition of solid sodium fluoroborate causes partial precipitation of the relatively insoluble complex fluoroborate. 

A solution of 5g of copper sulfate 5-hydrate in 40-ml of water is mixed with 9g of fresh ammonium persulfate (or llg of the potassium salt) in 40ml of water. The mixture is cooled in ice and stirred while 15ml of pure pyridine are added drop by drop from a buret. The violet-blue crystalline precipitate is suction-filtered, washed with two 15ml portions of 10% aqueous pyridine, and finally dried in a desiccator (not in vacuo, as the product loses pyridine). 

Ammonium salts were also used for weed control. These salts, ammonium thiocyanate, ammonium nitrate, ammonium sulfate, along with ammonium sulfamate were used as foliar sprays. The modes of action of these ammonium salts along with the use of other salts such as iron sulfate and copper sulfate cause desiccation and plasmolysis. 

Dissolve 12.5 grams (0.05 mole) of powdered copper sulfate pentahydrate in a mixture of 20 ml of concentrated ammonia and 12 ml of water, and slowly add to the blue solution 20 ml of ethyl alcohol. Allow it to stand about an hour, finally cooling thoroughly, and filter the crystals on a Buchner funnel. Wash first with a mixture of equal volumes of alcohol and concentrated ammonia, then with alcohol, and finally with ether. Dry in a desiccator over freshly ignited quicklime. The final product must be dry and free from alcohol. 

Amines such as diethylamine, morpholine, pyridine, and /V, /V, /V, /V -tetramethylethylene-diamine are used to solubilize the metal salt and increase the pH of the reaction system so as to lower the oxidation potential of the phenol reactant. The polymerization does not proceed if one uses an amine that forms an insoluble metal complex. Some copper-amine catalysts are inactivated by hydrolysis via the water formed as a by-product of polymerization. The presence of a desiccant such as anhydrous magnesium sulfate or 4-A molecular sieve in the reaction mixture prevents this inactivation. Polymerization is terminated by sweeping the reaction system with nitrogen and the catalyst is inactivated and removed by using an aqueous chelating agent. 

Obviously, the condensation of a carbonyl group with a diol produces 1 mol of water and because of the reversibility of the reaction (hydrolysis of the acetal), yields are lowered if this by-product is not removed. For such a purpose, there are essentially two possibilities (1) the continuous removal of water by an azeotropic distillation with a solvent mainly chosen for its boiling point (petroleum ether, benzene, toluene, xylene, for instance) (2) the presence of a desiccant (the most commonly taken is copper(II)sulfate, but sodium sulfate or molecular sieves have been also used) molecules known to be water scavengers, such as ortho-esters or dialkylsulfites, have also been suggested, even if they are seldom used in carbohydrate chemistry. 

CHAPTER 4 THE PREPARATION OF METAL AZIDES, FULMINATES, AND NITRIDES room temperature for 24 hours. Thereafter, slowly heat the mixture to about 80 Celsius with rapid stirring, and then carefully add 120 grams of 95% ethanol while stirring the reaction mixture. After the addition of the alcohol, remove the heat source, and allow the reaction mixture to cool to room temperature. Afterwards, rapidly filter-off the precipitated copper fulminate, wash with several hundred milliliters of cold water, and then dry in a desiccator filled with anhydrous magnesium sulfate. Should be stored in a desiccator over sodium sulfate in a refrigerator. 

Where higher temperatures have been employed, the reaction is conducted in the presence of a desiccant only, for example, anhydrous copper-(II) sulfate, or sodium sulfate. Many benzylidene acetals have been prepared either by heating the reactants alone at temperatures of over 100° or in a stream of carbon dixoide. Using the ethyl ester of meta-... 

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