CaHPO

Table 6 Hsts the leavening acids and the corresponding rates of reaction. The leavening acids most frequently used iaclude potassium acid tartrate, sodium aluminum sulfate, 5-gluconolactone, and ortho- and pyrophosphates. The phosphates iaclude calcium phosphate [7758-23-8] CaHPO, sodium aluminum phosphate, and sodium acid pyrophosphate (66).

Crystalline CaHPO 2H20 loses both water molecules in a single step at moderately elevated temperature or upon storage to yield the anhydrous salt. The presence of free moisture accelerates this dehydration, which results in anhydrous dicalcium phosphate, often as a hard mass. Addition of a few percent of tetrasodium pyrophosphate or trimagnesium phosphate, Mg2(P0 2> stabilizes the dihydrate. The mechanism, however, is not well understood. Nonetheless, these materials are used widely to stabilize CaHPO 2H20, particulady for toothpaste appHcations. 

In 1978, on the basis of a few measurements of urine calcium and phosphate excretion as well as an awareness of the previously mentioned work regarding the amounts of calcium and phosphate normally accreted in utero and postnatally, it became apparent that the demineralization, fractures and rickets we were seeing in our infants were caused by calcium deficiency. Consequently we increased the amount of calcium added to the parenteral alimentation solutions. If more than 12.5 mM of the calcium were added to a liter of hyperalimentation solution, gross precipitation would occur in the feeding solution. If 10 mM of calcium were added per liter, crystalline precipitated began to build up on the inside of our barium-impregnated silicone rubber central venous catheters. This crystalline precipitate resulted in gradual occlusion and functional loss of these lines. After several false starts and six lost catheters, chemical and crystal analysis showed that the precipitate inside these catheters was CaHPO. ... 

Despite the importance of the precipitation of calcium phosphates, there is still considerable uncertainty as to the nature of the phases formed in the early stages of the precipitation reactions under differing conditions of supersaturation, pH, and temperature. Although thermodynamic considerations yield the driving force for the precipitation, the course of the reaction is frequently mediated by kinetic factors. Whether dicalcium phosphate dihydrate (CaHPO HoO, DCPD), octacalcium phosphate (Ca HfPO, 2.5 H20, OCP), hydroxyapatite (Cag (PO fOH), HAP), amorphous calcium phosphate (ACP), or a defect apatite form from aqueous solution depends both upon the driving force for the precipitation and upon the initiating surface phase. Thermodynamically, the relative supersaturation, o, is given by... 

Secondary Calcium Phosphate Dicalcium Phosphate) CaHPO< + 2EUO. Mol. Wt. 172.14. 

The minerals in bone change as an animal ages. Juvenile or immature bone contains amorphous calcium phosphate or the mineral brushite (CaHPO 2H20). Mature bone contains the mineral hydroxyapatite (Ca5(P04)3(0H)), but with some modifications. There tends to be some internal crystal disorder within bone apatite, and the carbonate radical may substitute for phosphate. Calcium deficiency and other health problems may affect the composition and properties of bone. 

In discussions of the precipitation of calciinn phosphate, the phase which is usually emphasized is the thermodynamically most stable, HAP. However, most calcium phosphate solutions in which precipitation experiments are made, are initially supersaturated with respect to four additional phases. The solubility isotherms are shown in Figure 1 as a function of pH. Thus, at a pH of 7.0, in order of increasing solubilities, it is necessary to take into account tricalcium phosphate (Ca3(PO )2 hereafter TCP), octacalcium phosphate (Ca H(PO ). 2 1/2 H2O, hereafter OCP), anhydrous dicalcium phosphate (CaHPO, hereafter DCPA), and dicalciiam phosphate dihydrate (CaHPO. 2H2O, hereafter DCPD). The corresponding thermodynamic solubility products. 

SS, Cook Monsen Albumin egg Dextrose Corn oil CaHPO ... 

Calcium hydrogen phosphate CaHPO 7767-93-9 136.067 wh trici cry dec 2.92 0.02 iFtOH... 

I liter of water sat. with COj dissolves 0.561 gram CaHPO. at 25°. 

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