Polyphosphoric acid content

A number of commercial phosphoms-containing polyols have been made by the reaction of propylene oxide and phosphoric or polyphosphoric acid. Some have seen commercial use but tend to have hydrolytic stabiHty limitations and are relatively low in phosphoms content. BASF s Pluracol 684 is a high functionahty polyol containing 4.5% P, sold for Class 11 rigid foam use. 

Evaporated milk is a Hquid product obtained by the partial removal of water only from milk. It has a minimum milk-fat content of 7.5 mol % and a minimum milk-solids content of 25.0 mol %. Evaporated skimmed milk is a Hquid product obtained by the partial removal of water only from skimmed milk. It has a minimum milk-solids content of 20.0 mol %. Sweetened condensed milk is a product obtained by the partial removal of water only from milk with the addition of sugars. It has a minimum milk-fat content of 8.0 mol % and a minimum milk-solids content of 28.0 mol %. Skimmed sweetened condensed milk is a product obtained by the partial removal of water only from skimmed milk with the addition of sugars. It has a minimum milk-solids content of 24.0 mol %. AH may contain food additives (qv) as stabilizers, in maximum amounts, including sodium, potassium, and calcium salts of hydrochloric acid at 2000 mg/kg singly citric acid, carbonic acid, orthophosphoric acid, and polyphosphoric acid at 3000 mg/kg in combination, expressed as anhydrous substances and in the evaporated milk carrageenin may be added at 150 mg/kg. 

Pyrophosphoric (diphosphoric) acid, H4P2O2, is the only condensed phosphoric acid definitely obtainable ia crystalline form. It has a theoretical P2O5 content of 79.8%. However, Hquid polyphosphoric acid of such content shows by analysis only 42.5% the remainder is phosphoric acid and... 

In a reactor put 80 kg of polyphosphoric acid having the foliowing composition HsP30io 60% (HPOaie 10% H4P2O7 16% (HP03)x 10% total content in P2OS about 83% this is heated to about 160°C. 

Dilution of polyphosphoric acids with water in absence of cooling may lead to a large exotherm. Thus, tetraphosphoric acid diluted from 84 to 54% phosphorus pentoxide content rapidly attains a temperature of 120-140°C. 

Chloro-3-methylbenzothiophene. Heat 10 g (0.05 mol) of p-chlorophenyl-thio)acetone and 100 g of polyphosphoric acid (Section 4.2.58, p. 458) in a 250-ml flask on an oil bath maintained at 120-140 °C. When the contents of the flask initially reach the reaction temperature swirl vigorously to ensure thorough mixing of the reactants. After 2 hours allow the reaction mixture to cool and add 100 ml of water. Extract the organic product with ether, wash the combined extracts with water and dry over magnesium sulphate. Distil the residue under reduced pressure and collect 5-chloro-3-methylbenzothio-phene as a fraction of b.p. 98-100 °C/0.1 mmHg. The yield is 4.7 g (52%). 

Poly)phosphoric acids are thereby produced with diphosphorus(V) oxide contents of 54.5 and 61.5%. (In the USA, polyphosphoric acids with diphosphorus(V) oxide contents of 76 or 84% are often produced to save on transport costs. These are diluted on site before use.) Furnace phosphoric acids are very pure. If necessary, the low arsenic content can be reduced to less than 0.1 ppm by treatment with hydrogen sulfide and filtration of the sulfide formed. 

Polyphosphoric Acid. Phospholeum tetraphos-phoric add. May be prepd by heating HjPO, with sufficient phosphoric anhydride to give the resulting product an 82-85" PjO, content Ball, Ind, Eng. Chem. 44), 1464 (1949) Van Wazer, Holst, J- Am. Chem. Soc. 72, 639 (1950) Ken-nard, Org. Chem. Bull 29, no. 1 (1957). Consists of about 55% tripolyphosphoric acid, the remainder being HjP04 and other polyphosphoric acids. Typical analysts 83.0% PjOs ortho equivalent 115.0%. 

Personal care applications require minimal phosphoric acid and residnal alcohol levels, in addition to high MAP content. These requirements are necessary to minimize skin-irritation properties and to facilitate ease of formnlation [9]. The presence of phosphoric acid, for example, produces salt on nentralization, which may contribute to solubility or stability (phase separation) problems on formnlation. Conseqnently, considerable effort has been devoted to pnritication of polyphosphoric acid-derived materials. 

Figure 12.16 Fractions of the different polyphosphoric acids in the H2O-P2O5 system as a function of P2O5 content.

Polybenzimidazoles are normally highly soluble in polyphosphoric acid (PPA) which is commonly used as polycondensation solvent. From this solution, phosphoric acid-doped membranes can be obtained directly by casting the crude mixture as a thin film. A sol-gel transition is subsequently induced by hydrolyzing the PPA (good solvent) to orthophosphoric acid (poor solvent) under an atmosphere with carefully controlled temperature and humidity to control the acid content of the membrane [1]. This approach is further reviewed in Chap. 10. 

Syntheses of the 4-phosphates of D-glycero-D-gulo-heptose (Scheme 32) and D-glycero-L-manno-heptose have been reported by similar routes. Phosphorylation of W2Hco-inositol with polyphosphoric acid gave the hexakisphosphate, whereas epMnositol afforded a tetrakisphosphate only. The contents of inositol cyclic 1,2-phosphate and p-glucopyranose 1- and 6-phosphates in extracts from brain tissues have been determined by g.l.c. of the trimethylsilylated... 

The phosphorus content in some foods can be raised above the natural level using food additives based on polyphosphoric acid salts or salts of phosphoric acid. Polyphosphates are either sodium or potassium salts of polyphosphoric acids with straight chains and different degrees of polymerisation, M +2P 03 +i (6-30) or salts of cyclic polyphosphoric acids, (M POj) (6-31), which are actually oligomers of hydrogenphosphoric acid (m-phosphoric acid), HPO3. The most commonly used materials are sodium and potassium phosphates, especially disodium dihydrogendiphos-phate, tetrasodium diphosphate, sodium triphosphate and the so-called sodium hexametaphosphate. 

From the PBI/polyphosphoric acid sol the membrane is cast and further hydrolyzed. During the hydrolysis, the membrane undergoes a sol-gel transition which results in the final membrane used in Celtec MEAs (Fig. 2b). This production pathway not only produces high molecular weight PBIs with inherent viscosities of up to 7, but the final membrane also has a phosphoric acid content of more than 95 wt%, or up to 70 phosphoric acid molecules per PBI repeat unit. 

At equihbrium, the specific composition of a concentrated phosphoric acid is a function of its P2 s content. Phosphoric acid solutions up to a concentration equivalent of about 94% H PO (68% P2O5) contain H PO as the only phosphoric acid species present. At higher concentrations, the orthophosphoric acid undergoes condensation (polymerization by dehydration) to yield a mixture of phosphoric acid species (Table 5), often referred to genericaHy as polyphosphoric or superphosphoric acid, H20/P20 = - 3, or ultraphosphoric acid, H20/P20 = - 1. At the theoretical P2O5 concentration for orthophosphoric acid of 72.4%, the solution is actually a mixture containing 13% pyrophosphoric acid and about 1% free water. Because the pyrophosphoric acid present is the result of an equihbrium state dependent on the P2 5 content of the solution, pure orthophosphoric acid can be obtained because of a shift in equihbrium back to H PO upon crystallization. 

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