Calcium amalgam, preparation

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 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... 

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. 

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. 

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. 

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... 

Who do you suppose had a large hand in actually isolating the metals from these alkaline earths Who else but Sir Humphry Davy, fresh from his successful isolation of sodium and potassium. It turned out to be somewhat more difficult to isolate the 2A metals but, with the aid of work done by Berzelius and M. M. af Pontin, he was able, in 1808, to electrolyze moist lime in the presence of mercuric oxide to make an amalgam—that is, an alloy of mercury, which grudgingly yielded the silvery-white calcium metal. Today, calcium is prepared by the electrolysis of molten CaCl2 in the presence of Cap2 added to lower the melting point, as shown in Equation (13.2) ... 

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... 

Y-Phenylbutyric acid. Prepare amalgamated zinc from 120 g. of zinc wool contained in a 1-litre rovmd-bottomed flask (Section 111,50, IS), decant the liquid as completely as possible, and add in the following order 75 ml. of water, 180 ml. of concentrated hydrochloric acid, 100 ml. of pure toluene (1) and 50 g. of p benzoylpropionic acid. Fit the flask with a reflux condenser connected to a gas absorption device (Fig. II, 8, l,c), and boil the reaction mixture vigorously for 30 hours add three or four 50 ml. portions of concentrated hydrochloric acid at approximately six hour intervals during the refluxing period in order to maintain the concentration of the acid. Allow to cool to room temperature and separate the two layers. Dilute the aqueous portion with about 200 ml. of water and extract with three 75 ml. portions of ether. Combine the toluene layer with the ether extracts, wash with water, and dry over anhydrous magnesium or calcium sulphate. Remove the solvents by distillation under diminished pressure on a water bath (compare Fig. II, 37, 1), transfer the residue to a Claisen flask, and distil imder reduced pressure (Fig. II, 19, 1). Collect the y-phenylbutyric acid at 178-181°/19 mm. this solidifies on coohng to a colourless sohd (40 g.) and melts at 47-48°. 

Rubidium can be liquid at room temperature. It is a soft, silvery-white metallic element of the alkali group and is the second most electropositive and alkaline element. It ignites spontaneously in air and reacts violently in water, setting fire to the liberated hydrogen. As with other alkali metals, it forms amalgams with mercury and it alloys with gold, cesium, sodium, and potassium. It colors a flame yellowish violet. Rubidium metal can be prepared by reducing rubidium chloride with calcium, and by a number of other methods. It must be kept under a dry mineral oil or in a vacuum or inert atmosphere. 

Hydrogen can be prepared by the reaction of water or dilute acids on electropositive metals such as the alkali metals, alkaline earth metals, the metals of Groups 3, 4 and the lanthanoids. The reaction can be explosively violent. Convenient laboratory methods employ sodium amalgam or calcium with water, or zinc with hydrochloric acid. The reaction of aluminium or ferrosilicon with aqueous sodium hydroxide has also been used. For small-scale preparations the hydrolysis of metal hydrides is convenient, and this generates twice the amount of hydrogen as contained in the hydride, e.g. ... 

Creosol (also called 2-methoxy-jb-cresol, 4-methylguaiacol, and 3-methoxy-4-hydroxytoluene) has been obtained by the fractionation of beach creosote tar,4 by the reduction of vanillin by electrolytic methods,6 6 by hydrogen and palladium on charcoal or barium sulfate,7 8 with hydrazine,9 and by amalgamated zinc and hydrochloric acid.3 10 11 It has also been prepared by methyl-ation of 4-methylcatechol with methyl iodide 12 13 or with methyl sulfate 14 and is reported to be formed by the distillation of the calcium salt of 3-methoxy-4-hydroxyphenylacetic acid.16... 

Calcium - the atomic mmiber is 20 and the chemical symbol is Ca. The name derives from the Latin calx for lime (CaO) or limestone (CaCOj) in which it was foimd. It was first isolated by the British chemist Humphry Davy in 1808 with help from the Swedish chemist Jons Jacob Berzelius and the Swedish court physician M.M. af Pontin, who had prepared calcimn amalgam. 

Terbium metal is obtained from its anhydrous trifluoride, TbFs, or trichloride, TbCls, by thermal reduction with calcium, carried out in a tantalum crucible. Terbium produced by such methods may contain traces of calcium and tantalum. High purity metal can be prepared by various methods such as vacuum remelting, distillation, amalgam formation, floating zone melting, and various chemical processes. 

Dr. Pontin (M. M. af Pontin), 1781-1858. Physician to the King of Sweden. He collaborated with Berzelius in preparing amalgams of calcium and barium by electrolyzing lime or baryta in presence of mercury. Author of a biography of Berzelius. 

Numerous methods for the synthesis of salicyl alcohol exist. These involve the reduction of salicylaldehyde or of salicylic acid and its derivatives. The alcohol can be prepared in almost theoretical yield by the reduction of salicylaldehyde with sodium amalgam, sodium borohydride, or lithium aluminum hydride by catalytic hydrogenation over platinum black or Raney nickel or by hydrogenation over platinum and ferrous chloride in alcohol. The electrolytic reduction of salicylaldehyde in sodium bicarbonate solution at a mercury cathode with carbon dioxide passed into the mixture also yields saligenin. It is formed by the electrolytic reduction at lead electrodes of salicylic acids in aqueous alcoholic solution or sodium salicylate in the presence of boric acid and sodium sulfate. Salicylamide in aqueous alcohol solution acidified with acetic acid is reduced to salicyl alcohol by sodium amalgam in 63% yield. Salicyl alcohol forms along with -hydroxybenzyl alcohol by the action of formaldehyde on phenol in the presence of sodium hydroxide or calcium oxide. High yields of salicyl alcohol from phenol and formaldehyde in the presence of a molar equivalent of ether additives have been reported (60). Phenyl metaborate prepared from phenol and boric acid yields salicyl alcohol after treatment with formaldehyde and hydrolysis (61). 

The methods for producing diacetone alcohol are the action of barium hydroxide on acetone 1 the action of calcium hydroxide on acetone 2 the action of concentrated sodium hydroxide or potassium hydroxide on acetone 3 the action of magnesium amalgam on acetone 4 and the action of nitrous acid on diace-tonamine.5 The last method was not considered because of the difficulty of preparing diacetonamine. Of the methods employing acetone only, the first two seemed more promising, since the others are reported as giving low yields of impure product. It was soon found that barium hydroxide acted more rapidly than calcium hydroxide (as reported by L. P. Kyriakides) and this method was therefore employed. 

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