Oxalic acid, calcium salt

Calcium oxalate EiNECS 209-260-1 Ethanedioic acid, calcium salt (1 1) Oxalic acid, calcium salt (1 1). Cubic crystals d = 2.2 insoluble in H2O, AcOH, soluble in dilute HCI, HNOs-... 

Osmose K-33 Wood Preservative 982 Oxalic acid, calcium salt (1 1) 633... 

Oxalic acid occurs in high concentrations in pineapple and rhubarb, among other plants, and is responsible for the sharpness of the fresh fruits. Ingestion of too much oxalic acid can cause gastroenteritis, commonly recognized as a stomach ache. A salt of oxalic acid, calcium oxalate, is the stuff of kidney stones. 

L-Malic acid (HOOC CH2 CHOH COOH) for use in the pharmaceutical industry is manufactured by conversion of fumaric acid by the intracellular enzyme fumarase produced by various microorganisms. The excess fumaric acid is easily separated by crystallization after concentration of the mother solution. Further addition of lime allows malic acid to be separated as calcium malate within a bioreactor crystallizer system. By adding diluted sulfuric or oxalic acid, the salt is split into free malic acid and calcium sulfate or oxalate, the latter being removed by filtration (Mourgues et al., 1997). 

Calcium Oxalate. Ethanedioic acid calcium salt... 

The name oxalic acid is derived from one of its sources in the biological world, namely, plants of the genus Oxalis, one of which is rhubarb. Oxalic acid also occurs in human and animal urine, and calcium oxalate (the calcium salt of oxalic acid) is a major component of kidney stones. Adipic acid is one of the two monomers required for the synthesis of the polymer nylon 66. The U.S. chemical industry produces approximately 1.8 billion pounds of adipic acid annually, solely for the synthesis of nylon 66 (Section 16.4A). 

The requirements of the US Armed Forces are contained in Mil Spec JAN-B-660, Barium Oxalate (For Use In Ammunition) , (5 Aug. 1948) Color — white moisture — 0.3% max material insol in 10% HC1 soln - 0.5% max material sol in water - 0.3% max water sol alkalinity — 0.1% max water sol acidity — the water extract shall not be acid to methyl orange barium oxalate — 92% min calcium salts —... 

Resorption of the required mineral substances from food usually depends on the body s requirements, and in several cases also on the composition of the diet. One example of dietary influence is calcium (see p. 342). Its resorption as Ca is promoted by lactate and citrate, but phosphate, oxalic acid, and phytol inhibit calcium uptake from food due to complex formation and the production of insoluble salts. 

The oxalate, [Cr(NH3)4H20.Cl]C204, separates in violet-red crystals on the addition of potassium oxalate to a solution of the chloride. It is sparingly soluble in water, and the solution gives a precipitate of calcium oxalate with calcium chloride. A freshly prepared solution of the salt in nitric acid gives no precipitate with silver nitrate. The chlorine atom in the chloro-aquo-salts is within the complex, and hence silver chloride is not at first precipitated by silver nitrate on boiling with nitric acid and silver nitrate, however, chlorine is precipitated as silver chloride. 

Indicate the salts of calcium, strontium, and barium that are poorly soluble. How can you prove experimentally which of the calcium salts is the least soluble How does calcium oxalate react with acetic and hydrochloric acids How and why does the thermal... 

Other physical phenomena that may be associated, at least partially, with complex formation are the effect of a salt on the viscosity of aqueous solutions of a sugar and the effect of carbohydrates on the electrical conductivity of aqueous solutions of electrolytes. Measurements have been made of the increase in viscosity of aqueous sucrose solutions caused by the presence of potassium acetate, potassium chloride, potassium oxalate, and the potassium and calcium salt of 5-oxo-2-pyrrolidinecarboxylic acid.81 Potassium acetate has a greater effect than potassium chloride, and calcium ion is more effective than potassium ion. Conductivities of 0.01-0.05 N aqueous solutions of potassium chloride, sodium chloride, potassium sulfate, sodium sulfate, sodium carbonate, potassium bicarbonate, potassium hydroxide, and sodium hydroxide, ammonium hydroxide, and calcium sulfate, in both the presence and absence of sucrose, have been determined by Selix.88 At a sucrose concentration of 15° Brix (15.9 g. of sucrose/100 ml. of solution), an increase of 1° Brix in sucrose causes a 4% decrease in conductivity. Landt and Bodea88 studied dilute aqueous solutions of potassium chloride, sodium chloride, barium chloride, and tetra-... 

Calcium Oxalate. CaCtOj, white precipitate, insoluble in weak acids, but soluble in strong acids, formed by reaction of soluble calcium salt solution and ammonium oxalate solution. Solubility at I8°C 0.0056 g anhydrous salt per liter of saturated solution. 

Of nutrient chelates in the human diet, oxalates and phytules arc Ihe most common. Oxalic acid, found principally in spinach, rhubarb leaves, beet leaves, some fruits, and mushrooms, is u primary chelator of calcium. Oxalate present in pineapple, kiwifmil, and possibly in other foods, occurs as calcium oxalale. CaCiOj. This compound is in the form of needle-like crystals, known as raphidcs. which can produce painful sensations in the mouth when eaten raw. The effects of oxalic acid in the diet may he twofold. First, it forms strong chelates with dietary calcium, rendering the culcium unavailable for absorption and assimilation. Secondly, absorbed oxalic acid causes assimilated Ca to be precipitated as insoluble salts that accumulate in the renal glomeruli and contribute to the formation of renal calculi. 

The potassium or calcium salt form of oxalic add is distributed widely in the plant kingdom. Oxalic acid is found in spinach, rhubarb, etc. Oxalic acid is a product of metabolism of fungi or bacteria and also occurs in human and animal urine the calcium salt is a principal constituent of kidney stones. 

The mixture is then cooled by surrounding the crock with cold water, and about 1700 g. of cold 50 per cent sulfuric acid is added, until a filtered sample just fails to yield a further precipitate of calcium sulfate upon the further addition of sulfuric acid. The calcium sulfate is filtered off and washed with cold water. A saturated aqueous solution of oxalic acid is cautiously added to the filtrate until a filtered sample gives no test for calcium salts in solution (Note 4). 

The presence of only a slight excess of oxalic acid is permissible, although it is essential to remove all calcium salts since they would contaminate the final product but small quantities of free oxalic acid do not interfere with the subsequent operations and are removed in the mother liquors. 

Solubility of Salts.—The calcium salts of oxalic and tartaric acids are very sparingly soluble in cold water, calcium citrate is sparingly soluble in hot water. In some instances, as in the analysis of mixtures where an... 

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