Calcium oxide commercial preparation

L. Holmia, for Stockholm). The special absorption bands of holmium were noticed in 1878 by the Swiss chemists Delafontaine and Soret, who announced the existence of an "Element X." Cleve, of Sweden, later independently discovered the element while working on erbia earth. The element is named after cleve s native city. Holmia, the yellow oxide, was prepared by Homberg in 1911. Holmium occurs in gadolinite, monazite, and in other rare-earth minerals. It is commercially obtained from monazite, occurring in that mineral to the extent of about 0.05%. It has been isolated by the reduction of its anhydrous chloride or fluoride with calcium metal. 

Calcium Peroxide. Pure calcium peroxide [1305-79-9] Ca02, has been prepared, but the commercial product is a mixture made by reaction of calcium hydroxide and hydrogen peroxide. Commercial material contains either 60 or 75% Ca02 the remainder is a poorly defined mixture of calcium oxide, hydroxide, and carbonate. A well-defined octahydrate [60762-59-6] 8H20, can be crysta11i2ed from aqueous systems. 

Commercial tert.-butyl alcohol dried over calcium oxide is suitable for this preparation. Aluminum isopropoxide or ethoxide 2 may be used in place of the aluminum /er/.-butoxide to remove traces of water. The grade of metal known as fast cutting rods has proved most satisfactory. The checkers used turnings made from aluminum cast from melted-down kitchen utensils. Aluminum ferf.-butoxide has also been prepared successfully in another laboratory from commercially pure aluminum (2S) and from rods of the alloy 17ST (communication from L. F. Fieser). The checkers were able to obtain considerably higher yields of the butoxide from pure aluminum than from a copper-bearing alloy. 

Super-dry ethanol. The yields in several organic preparations (e.g. malonic ester syntheses, reductions involving sodium and ethanol, etc.) are considerably improved by the use of ethanol of 99.8 per cent purity or higher. This very high grade ethanol may be prepared in several ways from commercial absolute alcohol or from the product of dehydration of rectified spirit with calcium oxide. 

Almost all of the saltlike carbides contain the feC linkage and therefore may be called acetylides. The commercially important calcium carbide, CaC2, prepared by the high-temperature reaction of calcium oxide and carbon is typical of this class. When this compound is added to water, the strongly basic carbide ion, removes the hydrogen ions... 

Ethanol is commonly obtained in a 95 per cent and an absolute grade. The former has the composition of the azeotrope with water (bp 78.2°) and except for the water is quite pure. If absolute ethanol (bp 78.3°) is required, it may be prepared by heating the 95 per cent ethanol to reflux with calcium oxide for several hours and then distilling. However, absolute ethanol is available at a reasonable cost and is rarely prepared in a laboratory. The commercial absolute ethanol often contains a small amount of benzene, since it is prepared from 95 per cent ethanol by removing the water through the ternary azeotrope of benzene-ethanol-water (bp 65°). The absolute ethanol is therefore not suitable for use as a solvent for ultraviolet spectroscopy, and the 95 per cent ethanol is usually used. 

Absolute ethanol is very hygroscopic, and thus the commercial absolute ethanol and that prepared by treating the 95 per cent alcohol with calcium oxide usually contain about 0.5 per cent water. A common method for removing the residual water has been to add sodium, which reacts with water to form sodium hydroxide. However, since water is not much more acidic than ethanol, the equilibrium... 

Calcium Oxide. Lime burnt lime calx quicklime. GO mol wt 56.08. Ca 71.47%, O 28.53%. Properly stored line of commerce contains 90-95% free CaO. Commercial production from limestone W. L. Faith et al. Industrial Chemicals (John Wiley, New York, 3rd ed, 1965) pp 482-411. Ub prepn by ignition of CaCO, Ehrlich in Handbook si Preparative Inorganic Chemistry ml. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) p 931. Review R, S. Boynton in Kirk -Othmer Encyclopedia of Chemical Ttthealogy voL 14 (Wiley-Interscience, New York, 3rd ed.. Iffl) pp 343-382. 

The process for making calcium oxide is believed to be one of the first chemical reactions known to humans, dating back to prehistoric times. When limestone (calcium carbonate CaC03) is heated, carbon dioxide (C02) is driven off, leaving calcium oxide behind. The reaction was probably discovered very early in human history because limestone is a common, readily available material in the form of chalk and sea shells, and the amount of heat needed to produce the reaction can easily be produced in a simple wood fire. A more efficient method for carrying out the reaction is to heat the limestone in a kiln (oven) at temperatures of 5oo°C to ° (900°F to i,6oo°F), resulting in a more complete conversion of calcium carbonate to calcium oxide. This method is still used today for the commercial preparation of calcium oxide. 

The salt obtained by evaporating the solution to dryness is called gray acetate of lime. Commercial acetic acid is obtained from the calcium acetate so prepared by distilling with concentrated hydrochloric acid in copper stills. The acid is a slightly-colored liquid which contains about 50 per cent of acetic acid. It may be further purified by redistilling over a little potassium bichromate, which oxidizes some of the impurities, and by filtering through charcoal. 

Calcium oxide can absorb CO2 from pre-combustion systems. Natural sources of CaO, such as limestone, CaCOg, produce sorbents that lose reactivity relatively fast. Good CO2 sorbents were prepared with CaO precursors templated on three natural polysaccharides chitosan, agar and carrageenan, or three synthetic polymers poly(acrylic acid), poly(ethylene glycol) and poly(ethylene oxide-b-propylene oxide-b-ethylene oxide), respectively. Calcium oxide confined onto S5mthetic polymers exhibited better CO2 uptake activity and stability than CaO derived from commercial... 

Other patents (81,82) coveted the preparation of cellulose solutions using NMMO and speculated about their use as dialysis membranes, food casings (sausage skins), fibers, films, paper coatings, and nonwoven binders. NMMO emerged as the best of the amine oxides, and its commercial potential was demonstrated by American Enka (83,84). Others (85) have studied the cellulose-NMMO system in depth one paper indicates that further strength increases can be obtained by adding ammonium chloride or calcium chloride to the dope (86). 

Vanadium metal can be prepared either by the reduction of vanadium chloride with hydrogen or magnesium or by the reduction of vanadium oxide with calcium, aluminum, or carbon. The oldest and most commonly used method for producing vanadium metal on a commercial scale is the reduction of V20 with calcium. Recently, a two-step process involving the alurninotherniic reduction of vanadium oxide combined with electron-beam melting has been developed. This method makes possible the production of a purer grade of vanadium metal, ie, of the quaUty required for nuclear reactors (qv). 

Barium [7440-39-3] Ba, is a member of Group 2 (IIA) of the periodic table where it Hes between strontium and radium. Along with calcium and strontium, barium is classed as an alkaline earth metal, and is the densest of the three. Barium metal does not occur free in nature however, its compounds occur in small but widely distributed amounts in the earth s cmst, especially in igneous rocks, sandstone, and shale. The principal barium minerals are barytes [13462-86-7] (barium sulfate) and witherite [14941-39-0] (barium carbonate) which is also known as heavy spar. The latter mineral can be readily decomposed via calcination to form barium oxide [1304-28-5] BaO, which is the ore used commercially for the preparation of barium metal. 

Diacetunamine has been prepared in satisfactory yields by treating a mixture of commercial acetone and calcium chloride with anhydrous ammonia. The preparation from commercial acetone and ammonia is laborious and gives low yields. No yields are given in the older published descriptions of the preparation from mesityl oxide with either aqueous or anhydrous ammonia. The method described here has recently been published. ... 

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