Calcium acetate, reaction with

Chelating agents also are effective in certain cases. Ethylenediaminetetra-acetic acid (EDTA) forms strong chelates with alkaline earth elements and can be used to protect magnesium and calcium from reaction with phosphate, sulfate, selenium, boron, aluminum, and silicon. 8-Hydroxyquinoline has been used to protect magnesium and calcium from aluminum. 

A versatile method for the direct C-21 halogenation of a 20-ketopregnane was discovered by Ringold and Stork it consists of reaction with iodine-calcium oxide in tetrahydrofuran-methanol, and the resulting 21-iodo compound is displaced by acetate in the usual fashion ... 

An apparently related reaction involves iodination in pure methanol in the presence of calcium chloride. The main product is the 21,21-d3-iodo derivative, which on reaction with acetate ion gives, surprisingly, the 21-monoacetate ... 

Normal Fischer esterification of tertiary alcohols is unsatisfactory because the acid catalyst required causes dehydration or rearrangement of the tertiary substrate. Moreover, reactions with acid chlorides or anhydrides are also of limited value for similar reasons. However, treatment of acetic anhydride with calcium carbide (or calcium hydride) followed by addition of the dry tertiary alcohol gives the desired acetate in good yield. 

Theory Chlorinated lime reacts with acetic acid to produce a mole each of calcium acetate, hydrochloric acid and hydrochlorous acid. The two acids interact to give water and chlorine, and the latter reacts with HI to liberate iodine that can be estimated by titrating with 0.1 N sodium thiosulphate solution. The various reactions involved may be expressed as given below ... 

Fluoridated apatite crystals can grow using the dual membrane system involving on the one hand a calcium acetate solution and on the other hand a phosphate solution at physiological temperature with a pH of 6.5. lijima et al. showed that the combination of fluoride ions, added to the phosphate solution, and amelogenin (a major protein in the enamel extracellular matrix), present in the reaction space between the two membranes, controlled the transformation of octacalcium phosphate (OCP) into fine rod-like fluoridated apatite crystals with habit, size... 

The effect of calcium acetate in the reaction medium at higher concentrations of 4 was rather surprising as the enzymatic reaction proceeded without any problem at substrate loads as high as 3M (765 gL" ) with conversion values ranging from 42 to 48% after 24h (see Table 8.2, entries 1-4). Since the level of calcium acetate used in these experiments did not exceed 170 mM, which is well below a stoichiometric ratio between the carboxylate of 13 and Ca , a more complex mechanism that probably involves enzyme stabilization as well as com-plexation of product might be taking place. 

Calcium acetate is manufactured by the reaction of calcium carbonate or calcium hydroxide with acetic acid. 

Most syntheses start from 7-(5-oxocyclopentenyl)-heptanoic acid 198 followed by introduction of the hydroxy group at position C3 in two steps. We have repeated this synthesis and found, that the change of the very sensitive allylic bromide 199 into 201 is possible on different ways. The SN2 -reaction succeeds with silver acetate (way A), as well as with calcium hydroxide (way B) or in a phase transfer reaction with Bu4N+Br" (way C) (Scheme 2). 

Pastes inpregnated with PMMA or sulphur are still sufficiently permeable to water that expansion occurs on long exposure (F46). In polymer-impregnated (S108) and MDF (R64) cement pastes, there is evidence of interaction between Ca ions and carboxylate and possibly other groups of the polymer. In MDF pastes made with calcium aluminate cement, the polymer (PVA) was found to inhibit the normal hydration reactions of the cement, but to react with Ca and AH to give an ionically cross-linked polymer and calcium acetate. TEM showed the material to be essentially a dispersion of grains of clinker or hydration products in a continuous polymer matrix. 

Mutation data reported. Reacts with moisture to form sulfuric acid. Mixtures with calcium hypochlorite + starch + sodium carbonate explode when compressed. Violent reaction with acetic anhydride + ethanol may lead to ignition and a vapor explosion. Incompatible with calcium hypochlorite. When heated to decomposition it emits toxic fumes of SO and Na20. See also SULFATES. 

Kenyon and associates have compared the uronic acid values obtained by the above method with the carboxyl values obtained by the calcium acetate method. " In the latter procedure, a calcium acetate solution is added to cellulose which contains free carboxyl groups. A replacement reaction takes place, and the acetic acid liberated is titrated with sodium... 

The non-aqueous oxidation of various ketones and aldehydes to hydroxyaldehydes and hydroxy ketones has been carried out in two steps the first step is a bromination and the second a hydrolysis, or replacement of the bromine atoms by hydroxyl groups. Fischer and Landsteiner " brominated acetal in the presence of calcium carbonate (reaction 20). The bromoaldehyde Avas then treated with cold barium hydroxide solution (reaction 21) the resulting glycolic aldehyde was identified by conversion to glyoxal phenylosazone (reaction 22) and by the formation of calcium glycolate, after oxidation with bromine (reaction 23). 

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