Chloride magnesium

Economic Importance Since the manufacture of magnesium chloride is closely linked with the manufacture of metallic magnesium, it follows developments in this sector. In the mid-1970 s ca. 600 10 t/a of magnesium chloride was produced in the Western World, whereas it was ca. 520 10 t/a in 1996. 

Manufacture Magnesium is found in large quantities in nature. It is produced from different sources from the residual brines of the potash industry, (mainly as its hexahydrate), seawater, salt lakes, brines, magnesium carbonate (and hydrochloric acid) or magnesium oxide (and chlorine). 

In the Dow Chemical process calcium hydroxide is added to seawater, the precipitated hydroxide then being reacted with hydrogen chloride (the calcium precipitating as calcium sulfate due to the simultaneous addition of sulfuric acid) and the magnesium chloride solution is evaporated to dryness at ca. 200°C to produce a product with ca. 1.5 to 2 molecules of water. 

Anhydrous magnesium chloride is manufactured by dehydration of the hydrate at 300°C in a stream of hydrogen chloride. 

It can also be manufactured by the direct chlorination of magnesium oxide in the presence of coal at 1000 to 

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The major portion of sait is found in residues as these streams serve as the bases for fuels, or as feeds for asphalt and petroleum coke production, the presence of salt in these products causes fouling of burners, the alteration of asphalt emulsions, and the deterioration of coke quality. Furthermore, calcium and magnesium chlorides begin to hydrolyze at 120°C. This hydrolysis occurs rapidly as the temperature increases (Figure 8.1) according to the reaction i. ... 

By the electrolysis of fused magnesium chloride or fused sodium chloride. 

The precautions stated are to avoid uptake of oxygen, nitrogen and other impurities which render the metal brittle the excess magnesium and magnesium chloride can be removed by volatilisation above 1300 K. 

Alternatively, use the equivalent amount of n-butyl chloride and prepare the Grignard reagent as for aec.-biltyl magnesium chloride. 

Prepare a solution of benzyl magnesium chloride in a 2-litre three-necked flask from 24-3 g. of magnesium turnings, 600 ml. of sodium-dried ether and 126-5 g. (115 ml.) of redistilled benzyl chloride follow the experimental details given under n-Propylbenzene (Section IV,7). Cool the flask in running water or in ice water. Place a solution of 456 g. of n-butyl-p-toluenesulphonate (Section IV,198) in about twice its volume of anhydrous ether in the dropping funnel, and add it slowly with stirring, at such a rate that the ether just boils a white solid soon forms. The addition is complete after about 2 hours. Pour the reaction product... 

The metal is now principally obtained in the U.S. by electrolysis of fused magnesium chloride derived from brines, wells, and sea water. 

Electrolytic plant producing magnesium and chlorine from molten magnesium chloride. 

Magnesium trisihcate is prepared by precipitation of a solution of sodium siUcate of the proper composition, ie, MgO to Si02 ratio equal to 1 1.5, using a solution of magnesium chloride or sulfate. The precipitate of the magnesium trisihcate is filtered, washed, and dried at a low temperature. 

The polymerization is carried out at temperatures of 0—80°C in 1—5 h at a soHds concentration of 6—12%. The polymerization is terminated by neutralizing agents such as calcium hydroxide, calcium oxide, calcium carbonate, or lithium hydroxide. Inherent viscosities of 2-4 dL/g are obtained at 3,4 -dianiinodiphenyl ether contents of 35—50 mol %. Because of the introduction of nonlinearity into the PPT chain by the inclusion of 3,4 -dianiinodiphenyl ether kinks, the copolymer shows improved tractabiUty and may be wet or dry jet-wet spun from the polymerization solvent. The fibers are best coagulated in an aqueous equiUbrium bath containing less than 50 vol % of polymerization solvent and from 35 to 50% of calcium chloride or magnesium chloride. 

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