Calcium amalgams

L. calx, lime) Though lime was prepared by the Romans in the first century under the name calx, the metal was not discovered until 1808. After learning that Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, Davy was able to isolate the impure metal. 

The sodium produced contains 0.1—0.5 wt % mercury. This mercury is converted to calcium amalgam by treating the cmde sodium with powdered anhydrous calcium chloride ... 

The reaction of perfluoroalkyl iodides with calcium amalgam at -20 to 40 °C has been used to prepare perfluoroalkyl carbinols in 30-70% yields [/, 2] Aromatic aldehydes (equation 1) and ketones (equation 2) undergo this reaction, aliphatic aldehydes give high boiling mixtures The results are interpreted in terms of the intermediate formation of an organocalcium species... 

Calcium aluminate chloride, phase in Portland cement clinker, 5 472t Calcium aluminate fluoride, phase in Portland cement clinker, 5 472t Calcium aluminoferrite, phase in Portland cement clinker, 5 472t Calcium aluminoferrite hydrate, 5 477t Calcium—aluminum alloys, 4 530 Calcium amalgam, 22 773 Calcium ammonium nitrate, 2 724 Calcium analysis, of water, 26 37 Calcium A zeolite, separation of hydrocarbons by, 16 823 Calcium—barium—silicon alloy, 22 519 Calcium-bearing manganese silicon,... 

Lactitol is a disaccharide sugar alcohol prepared by reduction of the glucose residue to a sorbitol group. It is prepared by hydrogenation of a lactose solution hydrogenation at 100°C for 6 hr and 8825 kPa with a Raney nickel catalyst produces lactitol in nearly quantitative yield (van Velthuijsen 1979 Linko et al. 1980). Hydrogenation of lactose with sodium or calcium amalgam catalysts and reduction with sodium borohydride (Scholnick et al 1975) have also been successful. 

Sm Calcium amalgam Mg + HC1 SmCl3 in ethanol gives red SmCl2 SmCl3 in ethanol gives red SmCl2 0.1 [63]... 

Another one is to prepare vicinal, tertiary nitro compounds (XXI) by oxidative dimerization of the mononitro anion, followed by treatment of XXI with calcium amalgam in hexamethylphosphoramide [77] at room temperature. 

MERCURIC IODIDE or MERCURIC IODIDE, RED (7774-29-0) Hglj Aqueous solution is a weak reducing agent. Incompatible with acetylene, alkalis, ammonia, azides, chlorine dioxide, azides, bromides, calcium (amalgam formation), chlorides, cyanides, copper salts hydrogen... 

Fig. 356. Preparation of calcium amalgam, b steel bomb, 19 cm. long, 5.5 cm. I.D., 9 mm. wall thickness capacity 45 ml. up to the screw thread s movable piston k steel head r pressime-reducing valve m pressure gage d copper pressure tubing for introduction of Ng.

Calcium amalgam, Ca/Hg. The amalgam is prepared by treating calcium shot with mercuric chloride in DMF and HMPT. 

Alkene synthesis from lc-dinitro compounds. In the original synthesis (4, 460-461), sodium sulfide (or sodium thiophenoxide) was used as the reducing agent. This method, however, does not tolerate various functional groups ester, keto, cyano, or ether. This defect can be remedied by use of calcium amalgam, which reduces nitro groups more readily than other common functional groups. Examples ... 

ALKENES Calcium amalgam. N,N-Dimethylformamide dimethyl acetal. N,N-Methylphenylaminotriphenyl-phosphonium iodide. N,N,N, NrTetra-methyldiamidophosphorochloridate. Titanium(O). p-Toluenesulfonylhydra-zine. Tii-n-butyltin hydride. Triphenyl-phosphine-Diethyl azodicaiboxylatc. Trityl tetrafluoroborate. 

Calcium was first isolated by Sir Humphry Davy in 1808. Davy produced calcium amalgam by electrolyzing an aqueous solution of the chloride, CaCl, using a liquid-mercury cathode such as in the chlor-alkali process employing a mercury cathode. After distilling mercury from the amalgam formed, he obtained the pure calcium metal. His discovery showed lime to be an oxide of calcium. Later, Moissan reduced the calcium diiodide with sodium. The first industrial production of calcium metal was reported in 1904 and attributed to Brochers and Stockem, who prepared it by electrolysis of the molten chloride. This process was discontinued in 1940 and replaced by aluminothermic reduction of the oxide. 

Several dialkyls and diaryls of calcium have been prepared from the corresponding mercury derivatives R2Hg and calcium or calcium amalgam in THF. Again experimental technique is crucial to success the quality of the metal, its state of division and the cleanliness of its surface are especially important. Nevertheless, dimethylcalcium has been obtained in 96% yield as a white solid sparingly soluble in THF. Dialkyls and diaryls of Sr and Ba are even more difficult to prepare. Diethylstrontium attacks THF above — 30°C. The reaction between Et Hg and Sr was initiated at - 10°C for 15 minutes and then completed during... 

Calcium — (L. calx, lime), Ca at. wt. 40.078(4) at. no. 20 m.p. 842°C b.p. 1484 C sp. gr. 1.55 (20°C) valence 2. Though lime was prepared by the Romans in the first century under the name calx, the metal was not discovered until 1808. After learning that Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, Davy was able to isolate the impure metal. Calcium is a metallic element, fifth in abundance in the earth s crust, of which it forms more than 3%. ft is an essential constituent of leaves, bones, teeth, and shells. Never found in nature uncombined, it occurs abundantly as limestone (CaCO ), gypsum (CaSO 2H2O), and fluorite... 

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