Phosphate, orthophosphoric acid

H1C phosphate orthophosphoric acid (AP+ andZn"+) calcined 2inc oxide, calcined magnesium oxide oxides phosphate luting agent, base... 

Orthophosphate salts are generally prepared by the partial or total neutralization of orthophosphoric acid. Phase equiUbrium diagrams are particularly usehil in identifying conditions for the preparation of particular phosphate salts. The solution properties of orthophosphate salts of monovalent cations are distincdy different from those of the polyvalent cations, the latter exhibiting incongment solubiUty in most cases. The commercial phosphates include alkah metal, alkaline-earth, heavy metal, mixed metal, and ammonium salts of phosphoric acid. Sodium phosphates are the most important, followed by calcium, ammonium, and potassium salts. 

Phosphate Esters. Mono and diesters of orthophosphoric acid ... 

Condensed phosphates are indirectly manufactured derivatives of phosphorous acids, having less water than orthophosphoric acid (two molecules of phosphoric can be written P205 3H20, which indicates the source of the condensation reaction). Condensed phosphates are typically available in either crystalline or glassy forms. 

The analysis of phosphates and phosphonates is a considerably complex task due to the great variety of possible molecular structures. Phosphorus-containing anionics are nearly always available as mixtures dependent on the kind of synthesis carried out. For analytical separation the total amount of phosphorus in the molecule has to be ascertained. Thus, the organic and inorganic phosphorus is transformed to orthophosphoric acid by oxidation. The fusion of the substance is performed by the addition of 2 ml of concentrated sulfuric acid to — 100 mg of the substance. The black residue is then oxidized by a mixture of nitric acid and perchloric acid. The resulting orthophosphate can be determined at 8000 K by atom emission spectroscopy. The thermally excited phosphorus atoms emit a characteristic line at a wavelength of 178.23 nm. The extensity of the radiation is used for quantitative determination of the phosphorus content. 

The phosphate bonded cements described in this chapter are the products of the simple acid-base reaction between an aqueous solution of orthophosphoric acid and a basic oxide or silicate. Such reactions take place at room temperature. Excluded from this chapter are the cementitious substances that are formed by the heat treatment of aqueous solutions of acid metal phosphates. 

Here we are concerned with the cement-forming reaction between orthophosphoric acid solutions and basic oxides and silicates where the reaction is much simpler. Polymeric phosphates are not involved, there are no P-O-P bonds, and the structural unit is the simple [POJ tetrahedron. 

Dental silicate cement was also variously known in the past as a translucent, porcelain or vitreous cement. The present name is to some extent a misnomer, probably attached to the cement in the mistaken belief that it was a silicate cement, whereas we now know that it is a phosphate-bonded cement. It is formed by mixing an aluminosilicate glass with an aqueous solution of orthophosphoric acid. After preparation the cement paste sets within a few minutes in the mouth. It is, perhaps, the strongest of the purely inorganic cements when prepared by conventional methods, with a compressive strength that can reach 300 MPa after 24 hours (Wilson et al, 1972). 

Dental silicate cement liquids are concentrated aqueous solutions of orthophosphoric acid generally containing aluminium and zinc (Wilson, Kent Batchelor, 1968 Kent, Lewis Wilson, 1971a,b Wilson et al., 1972). The optimum orthophosphoric acid concentration is 48 to 55 % by mass (Wilson et al, 1970a), although higher concentrations are encountered. Aluminium is present as phosphate complexes and zinc as a simple ion (see Section 6.1.2). Examples are given in Table 6.6. 

Genge, J. A. R. Salmon, J. E. (1959). Aluminium phosphates. Part III. Complex formation between tervalent metals and orthophosphoric acid. Journal of the Chemical Society, 1459-63. 

Of the three organic phosphorus insecticides—hexaethyl tetraphosphate, tetraethyl pyrophosphate, and parathion—the first two have been shown to be mixtures (36) that contain tetraethyl pyrophosphate as the principal active ingredient. Several methods have been proposed for the determination of this compound in the commercial products (25, 35). All are based on the separation of the tetraethyl pyrophosphate from the related ethyl phosphates, followed by its hydrolysis to diethyl orthophosphoric acid and titration with standard alkali. Both hexaethyl tetraphosphate and tetraethyl pyrophosphate are soluble in water and are rapidly hydrolyzed to monoethyl and diethyl orthophosphoric acid. This rapid hydrolysis to nontoxic products greatly limits the duration of the in- secticidal effectiveness of tetraethyl pyrophosphate, but it also eliminates the danger of toxic residues on the crops treated. 

Synthetic fire-resistant fluids have been developed to replace petroleum-based fluids for many applications. Although there are several types of these less hazardous fluids, the only synthetic fluids discussed in this profile are phosphate esters and polyalphaolefins. The phosphate esters are tertiary esters of orthophosphoric acid, 0=P(0H)3, and may be triaryl, trialkyl, and alkyl/aryl. The polyalphaolefins are usually based on 2-decene and contain a mixture of oligomers (dimers, trimers, etc.). 

Anilinediphenylamine phosphate 1 ml aniline + 1 g diphenylamine in 100 ml acetone. Add 10 ml 85% orthophosphoric acid Dip Reaction with aromatic amine in hot acid... 

Orthophosphoric acid and pyrophosphoric acid are preferred catalysts. Phosphorus pentoxide is catalytically active but no conclusive evidence has been described to show whether or not its activity depends on the presence of traces of water as promoter. Copper pyrophosphate and acid phosphates of cadmium are also good catalysts that the former probably owes its activity to partial conversion to acid or acidic salt under the polymerization conditions seems to be shown by the fact that there is an induction period. A composite prepared by calcining kiesel-guhr impregnated with orthophosphoric acid (the so-called solid phosphoric acid ) has found wide commercial use. 

Similarly, the reaction of propene with 90% orthophosphoric acid at 125° at an initial pressure of 10 atmospheres yielded a homogeneous liquid product which presumably contained isopropyl phosphate (Ipatieff, 56). When this liquid was heated at 150° two layers were formed. The upper layer consisted of propylene polymer and the lower layer was phosphoric acid which was capable of polymerizing additional propene. 

In accordance with the two ester mechanism, the first step in the polymerization of ethylene in the presence of phosphoric acid is the formation of an ethyl phosphate (Ipatieff and Pines, 70). It was found that rapid absorption of ethylene took place when orthophosphoric acid was treated with etyhlene at 180° under an initial pressure of 50 atmos-... 

Phosphate monoesters P-signals located at 4.0—4.5 ppm relative to external 80% orthophosphoric acid. Phospholipids P-signals located at -0.4—1.2 ppm. 

Phosphoric acid (orthophosphoric acid), as well as the different phosphoric acids, can ionize to form corresponding phosphates. When phosphoric acid loses its three hydrogen ions, it becomes the phosphate or orthophosphate ion, P043. Likewise, when the polyphosphoric acids lose their hydrogen ions, the corresponding polyphosphate ion is produced. For example,... 

Orthophosphoric Acid. Reactionfor DeterminingOrthophosphoric Acid and Its Salts. 1. Pour molybdenum liquid into a solution of sodium hydrogen phosphate or phosphoric acid. What is the composition of the precipitate Write the equation of the reaction. Does the precipitate dissolve in nitric acid ... 

Calcium Salts of Orthophosphoric Acid. Pour a calcium chloride solution into three test tubes. Add ammonia and a sodium hydrogen phosphate solution to one of them, only a sodium hydrogen phosphate solution to the second one, and a sodium dihydrogen phosphate solution to the third one. What do you observe Write the equations of the reactions and explain how the medium affects the course of the process. 

About one-tenth of the P in milk (i.e., about 100 mg/liter) is in the form of water-soluble organic esters of orthophosphoric acid. A list of such esters that have been detected in milk is presented in Table 1.8. Most of them are sugar phosphates and constituents of phospholipids. Reported concentrations of some of the compounds vary considerably, and complete quantitation of the group has not been made. 

Wet-Protes Orfhoplutsphoric Acid contains 30-54% IhO. by weight. When sulfuric acid is added to phosphate rocks in a proportion greater than needed to make single superphosphate, orthophosphoric acid. HjPOj. is produced. This acid is used as an intermediate in preparing other phosphates,... 

The determination of OXO in Japanese oyster was realized using reversed-phase HPLC. Samples were extracted with LLE and SPE recoveries were 88.3% (193). Oyster samples were homogenized with a phosphate buffer adjusted to pH 7. After centrifugation, supernatants were concentrated using an SPE C-18 cartridge. Before use, the cartridge was activated with MeOH and phosphate buffer. After the sample had been passed, the cartridge was flushed with water and the analytes were eluted with MeOH-orthophosphoric acid (9 1). The eluate was evaporated, and the residues were dissolved in the mobile phase. The method developed was validated and the study of OXO stability was performed. The limits of detection and determination were 10 and 40 ng/ml, respectively. 

When an aq. soln. of trimetaphosphimic acid, or of one of its salts, acidified with one of the stronger mineral acids, is heated or kept for a long time, decomposition occurs—slowly if cold, rapidly if heated. Orthophosphoric acid and ammonia (ammonium phosphate) are the ultimate products of the decomposition. Several intermediate products have been detected in addition to pyrophosphoric acid, what H. N. Stokes calls diimidotriphosphoric acid, and imidodiphosphoric acid have been found, and he represents the different stages of the decomposition ... 

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