Calcium oxide preparation

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. 

One such decontaminant is supertropical bleach (STB). STB is a mixture of chlorinated lime and calcium oxide containing about 30% available chlorine. It can be used either as a dry mix or as a slurry to decontaminate some equipment surfaces and terrain. The dry mix is prepared with two parts bleach to three parts earth by volume. A slurry typically consists of 40 parts STB to 60 parts by weight of water. This material is then sprayed or swabbed on the contaminated surface (see Bleaching agents). STB is an effective decontaminant for mustard, lewisite, and VX. It is less effective against nerve agents other than VX. 

Calcium Oxide. Also called lime or quicklime (4,5), calcium oxide [1305-78-8] (Class 1, nonregenerative), is relatively iaexpensive. It is prepared by roasting calcium carbonate (limestone) and is available ia a soft and a hard form according to the way ia which it was burned. For desiccant service, soft-burned lime should always be used. Calcium oxide is most commonly used to dehydrate Hquids and is most efficient when it can be heated to speed the reaction rate. The reaction product is calcium hydroxide, which cmmbles as it picks up moisture. 

DihydroxyanthraquiQone (anthranifin) [117-12-4] (47) is an important iatermediate for manufacturiag disperse blue dyes, eg. Cl Disperse Blue 73 (113), and is prepared from anthraquiQone-l,5-disulfonic acid by heating with an aqueous suspension of calcium oxide and magnesium chloride under pressure at 200—250°C (67). Alternative methods have been proposed, ie, direct replacement of the NO2 groups of 1,5-dinitroanthraquiaone (49) (68) or the route via 1,5-dimethoxyanthraquiaone [6448-90-4] (48) and subsequent hydrolysis (69). 

The most versatile method for preparing enamines involves the condensation of aldehydes and ketones with secondary amines [Eq. (1)]. Mannich and Davidsen (/) discovered that the reaction of secondary amines with aldehydes in the presence of potassium carbonate and at temperatures near 0° gave enamines, while calcium oxide and elevated temperatures were required to cause a reaction between ketones and secondary amines, although usually in poor yield. The introduction by Herr and Heyl 2-4) of the removal of the water produced in the condensation by azeotropic distillation with benzene made possible the facile preparation of enamines from ketones and disubstituted aldehydes. 

Calcium phthalocyanine (PcCa) can be prepared by the reaction of calcium oxide with phthalonitrile58 or by the reaction of dilithium phthalocyanine and calcium chloride in ethanol.59... 

Aziridines can be prepared directly from double-bond compounds by photolysis or thermolysis of a mixture of the substrate and an azide. The reaction has been carried out with R = aryl, cyano, EtOOC, and RSO2, as well as other groups. The reaction can take place by at least two pathways. In one, the azide is converted to a nitrene, which adds to the double bond in a manner analogous to that of carbene addition (15-62). Reaction of NsONHC02Et/ CuO [Ns = A(/7-toluenesulfonyl-inimo)] and a conjugated ketone, for example, leads to the A-carboethoxy aziridine derivative.Calcium oxide has also been used to generate the nitrene.Other specialized reagents have also been used." ... 

Interaction of the 3 2 complex with iron(III) chloride and calcium oxide, mercury oxide or silver oxide was usually too violent for preparative purposes, but zinc oxide was satisfactory. Reaction with water was violent. 

Early studies using calcium oxide, carbonate, and carboxylates reported low activities for the polymerization of LA, even in bulk at 120-180 °C.827,828 PolyGA and copolymers of GA with CL and L-LA have been prepared using Ca(acac)2, but again high temperatures (150-200 °C) are required.829 Under these conditions transesterification occurs, although to a lesser extent than in analogous Sn(Oct)2-initiated polymerizations. 

The usual agent used for the purpose is calcium oxide (quicklime). In its dry powder form dispersion in the rubber compound is a serious problem. Thus, the chemical is offered in a variety of carrying media to ensure adequate dispersion and, in most cases, to prevent moisture uptake by the calcium oxide after preparation and prior to incorporation in the rubber compound. 

Diphenylcyclopropane has been prepared in 24% yield by the Simmons-Smith reaction,2 in 78% yield by treatment of 3,3-diphenylpropyltrimethylammonium iodide with sodium or potassium amide,3 in 61% yield by reaction of 1,1-diphenyl-ethylene with dimethylsulfonium methylide,4 and in unspecified yields from 1,1-diphenylethylene by reaction with diazomethane followed by pyrolysis of the resulting pyrazoline or by reaction with ethyl diazoacetate followed by distillation of the corresponding acid over calcium oxide.5... 

Titration of soil pH is an old method that is not widely used today. Basically, an acid soil suspension is prepared and titrated with a standardized base, often sodium hydroxide, although various basic calcium compounds such as calcium oxide (CaO) and calcium hydroxide [Ca(OH)2] can also be used. Because of the dark color of many soils, they are often titrated using a pH meter as the indicator of the end point. A setup for the titration of soil is shown in Figure 10.1. Titration is slow in that it takes some time after the addition of titrant for some semblance of equilibrium to be reached. Once this happens, a reading can be made or simply another addition of titrant made. 

Niacin is found in many foods, including corn. The niacin in corn, however, cannot be absorbed in the intestinal tract. In regions of the world where corn is a major part of the diet, niacin deficiency can occur. If you add calcium oxide or wood ash to the water in which you boil corn, the resulting basic solution allows the niacin to be absorbed. The flour for making corn tortillas is commonly prepared using this method. 

Calcium chloride is obtained as a by-product in the manufacture of sodium carbonate (soda ash) by ammonia-soda (Solvay) process. The process involves the reaction of sodium chloride with calcium carbonate and ammonia. Calcium chloride is currently produced in bulk amounts by evaporation of natural underground brines. In the laboratory, calcium chloride can be prepared by treating bmestone with hydrochloric acid followed by evaporation of solution to obtain crystals. The crystals are dehydrated to obtain anhydrous salt. Calcium oxide or hydroxide may be used instead of carbonate. 

Alternatively, calcium hydride may be prepared by the reduction of calcium oxide with magnesium in the presence of hydrogen ... 

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). 

A 200-ml. three-necked flask is equipped with a thermometer, a mechanical stirrer, a gas inlet tube extending as far into the flask as the stirrer permits, and a trap (designed to return the heavier layer of the condensate) (Note 1), which is attached to a bulb and a coil-type reflux condenser connected in series. Methyl p-ethylbenzoate (98 g., 0.597 mole) (Note 2) and a mixture of 1 g. of chromium oxide and 4 g. of calcium carbonate, prepared by grinding the solids together in a mortar, are added. An air line with a bleed control valve (Note 3) is connected from the top of the condenser to a water aspirator. The flask is heated with a hemispherical electric mantle (Note 4). 

Sodium and potassium oxides cannot be conveniently made by calcining the corresponding carbonate and digesting the residue with water as is possible in the case of calcium oxide, because the two alkali carbonates do not decompose so readily on ignition as calcium carbonate. Lithium carbonate, however, is more closely related to calcium carbonate than the other alkali carbonates. The preparation of the oxides of potassium and sodium is rather difficult and expensive. 

When preparing zirconium iodide, take 20% less iodine than the stoichiometric amount. Place the iodine into test tube 1 and spill a mixture of potassium iodide and freshly prepared calcium oxide (2-3 g) onto it. 

Lac sulfur 1s prepared by boiling a suspension of 33 g of calcium oxide and 50 g of sublimed sulfur (Fisher Scientific Company) in 200 mL of water for 30 min, then filtering the hot solution and acidifying the clear filtrate to pH 5 with hydrochloric acid. The precipitated sulfur is collected, washed with water, and dried in a vacuum desiccator. 

Protection from Moisture.—The moisture in the air may act upon chemical preparations in a variety of ways. (1) It may combine with the preparation to form an entirely different compound, as when calcium oxide is converted into the hydroxide. (2) With very soluble salts it may occasion deliquescence (see Exercise 7). (3) It may occasion hydrolysis. This last case... 

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. 

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