Calcium phosphate and

Phosphoms oxyfluoride is a colorless gas which is susceptible to hydrolysis. It can be formed by the reaction of PF with water, and it can undergo further hydrolysis to form a mixture of fluorophosphoric acids. It reacts with HF to form PF. It can be prepared by fluorination of phosphoms oxytrichloride using HF, AsF, or SbF. It can also be prepared by the reaction of calcium phosphate and ammonium fluoride (40), by the oxidization of PF with NO2CI (41) and NOCl (42) in the presence of ozone (43) by the thermal decomposition of strontium fluorophosphate hydrate (44) by thermal decomposition of CaPO F 2H20 (45) and reaction of SiF and P2O5 (46). 

Both monocalcium phosphate and dicalcium phosphate dissolve incongmently in water, disproportionating to more basic calcium phosphate and phosphoric acid. The extent of these reactions varies with the temperature and the amount of water. If water is added gradually to anhydrous monocalcium phosphate, equiUbrium conditions first correspond to a mixture of the anhydrous salt and its monohydrate. After conversion to the monohydrate, further reaction affords dicalcium phosphate plus free phosphoric acid. Dicalcium phosphate decomposes in aqueous solution to the more basic hydroxyapatite and phosphoric acid via intermediate octacalcium phosphate. The compHcated stepwise conversion of the acidic mono- and dicalcium phosphates to hydroxyapatite is summarized in equations 6—9. The kinetics are quite complex. 

Weaker complex ions may also form with orthophosphates, eg, CaH2PO" 4 in mildly acidic solutions of calcium phosphates, and FeHPO" 4 as a colorless species in impure phosphoric acid. Anionic complexes such as Fe(HPO 2 o known. 

Although they may be completely soluble in the lower temperature bulk water, these compounds (eg, calcium carbonate, calcium phosphate, and magnesium siUcate) supersaturate in the higher temperature water adjacent to the heat-transfer surface and precipitate on the surface. 

When it is desirable to use a weak black, bone black may be substituted for carbon. It is manufactured by calcining animal bones and contains approximately 85% calcium phosphate and calcium carbonate. Black iron oxide (Fe O is stable up to 150°C. Copper chromite black (Cu(Cr02)2) is iuert to all but mbberlike compositions and has been calcined to 600°C. 

Charcoal is generally satisfactorily activated by heating gently to red heat in a crucible or quartz beaker in a muffle furnace, finally allowing to cool under an inert atmosphere in a desiccator. Good commercial activated charcoal is made from wood, e.g. Norit (from Birch wood), Darco and Nuchar. If the cost is important then the cheaper animal charcoal (bone charcoal) can be used. However, this charcoal contains calcium phosphate and other calcium salts and cannot be used with acidic materials. In this case the charcoal is boiled with dilute hydrochloric acid (1 1 by volume) for 2-3h, diluted with distilled water and filtered through a fine grade paper on a Buchner flask, washed with distilled water until the filtrate is almost neutral, and dried first in air then in a vacuum, and activated as above. To improve the porosity, charcoal columns are usually prepared in admixture with diatomaceous earth. 

Besha, K., Key, C, Glimcher, M., Schimizu, M. and Griffin, R.G. 1990 Solid state carbon-13 and proton NMR studies of carbonate-containing calcium phosphates and enamel. Journal of Solid State Chemistry 84 71-81. 

Driessens, F.C.M., van Dijk, J.W.E. and Borrgreven, J.M.P.M. 1978 Biological calcium phosphates and their role in the physiology ofbone and dental tissues. 1. Composition and solubility of calcium phosphates. Calcified Tissue Research 26 127-137. 

It is the formation of this material which makes the reaction have a low atom economy and, owing to the cost of disposal (usually by conversion to calcium phosphate and disposal as hazardous waste), has limited its commercial usefulness to high value products. Several methods have been developed to recycle (Ph)3PO into (Ph)3P but these have proved more complex than might be expected. Typically the oxide is converted to the chloride which is reduced by heating with aluminium. Overall this recovery is expensive and also produces significant amounts of waste. 

Adsorption. The adsorption of the components of a vaccine on to a mineral adjuvant. The mineral adjuvants, or carriers, most often used are aluminium lydroxide, aluminium phosphate and calcium phosphate and their effect is to increase the immunogenieity and decrease the toxicity, local and systemic, of a vaccine. Diphtheria vaccine, tetanus vaccine, diphtheria/tetanus vaccine and diphtheriaAetanus/pertussis vaccine are generally prepared as adsorbed vaccines. 

Black Organic Pigments Charred bone, Mixture of charcoal, calcium phosphate, and... 

White Burned bone Mixture of calcium phosphate and calcium... 

The casein, which is contaminated with calcium phosphate and fats, is filtered off to as small a volume as possible (about 500 cc.) and transferred to a 2-1. beaker. It is then treated with 0.1 M sodium hydroxide, the alkali being added slowly and with stirring through a capillary extending to the bottom of the beaker (Note 4). The addition of alkali is continued until the / ll of the mixture reaches 6.3 (Note 5) 100-150 cc. of the alkali is required. The end-poinl is determined by matching against... 

Calcium Phosphates and Carbonates in Bioinspired and Biomimetic Materials 9... 

A fertilizer that provides both phosphorus and nitrogen is prepared by the reaction of calcium phosphate and nitric acid. 

Most of this section will be devoted to summarizing information relating to the stability constants reported for complexes of this group of Ca2+-binding ligands. However, we shall precede this main part with a short mention of a few relevant structures. Other properties of calcium phosphates and phosphonates will be mentioned in Sections VIII.B.4 and VIII.D below. An overall view of complexes of nucleosides, nucleotides, and nucleic acids is available (670). 

Table 13.13 Overview of the adjuvant preparations that have been developed to date, or are under investigation. Of these, aluminium-based substances are the only adjuvants used to any significant degree in humans. Calcium phosphate and oil emulsions find very limited application in human medicine...

Adsorption on calcium pectate and calcium phosphate, and chromatography on DEAE-cellulose, were used for the purification of pectin lyase from Aspergillus fonsecaeus.253 Two forms of pectin lyase (having pH optima at 7.3 and 8.3) were isolated266 from the culture filtrate of Sclerotinia fructigena by chromatography on Seph-adex G-75 and CM-Sephadex C-50. 

Calcium Phosphates And Calcified Tissues. Precipitation in the system Ca(0H)2 - H3PO4 - H2O can lead to the formation of several calcium phosphates (shown in Table IV), of which hydroxy-apatite 0HA is the most stable above a pH of about 4.1. The relative stabilities are illustrated in Figure 12. 

As is true today, most phosphate in the primordial crust must have been sequestered in nearly insoluble calcium phosphates and carbonates or in basalts, and only dissolved monomeric phosphate was produced by weathering. [201] However, the volatile polyphosphate P4O10 is known to be a component of volcanic gases. [205] This material originates from the polymerization of phosphate minerals in mag-... 

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