Metaphosphates solutions

Phosphate Esters. The phosphorylation of sucrose using sodium metaphosphate has been reported (78). Lyoptulization of a sodium metaphosphate solution of sucrose at pH 5 for 20 hours followed by storage at 80°C for five days produced a mixture of sucrose monophosphates. These products were isolated by preparative hplc, with a calculated yield of 27% based on all organic phosphate as sucrose monoesters. Small proportions of glucose and fmctose were also formed. 

Elemental composition P 38.73%, H 1.26%, O 60.01%. The compound may be identified by physical properties alone. It may be distinguished from ortho and pyrophosphates by its reaction with a neutral silver nitrate solution. Metaphosphate forms a white crystalline precipitate with AgNOs, while P04 produces a yellow precipitate and P20 yields a white gelatinous precipitate. Alternatively, metaphosphate solution acidified with acetic acid forms a white precipitate when treated with a solution of albumen. The other two phosphate ions do not respond to this test. A cold dilute aqueous solution may be analyzed for HPO3 by ion chromatography using a styrene divinylbenzene-based low-capacity anion-exchange resin. 

Metaphosphoric Acid. Reactions jor Determining Metaphosphoric Acid and Its Salts. 1. Pour about 1 ml of an aqueous protein solution into a test tube and add to it approximately the same amount of a sodium metaphosphate solution acidified with acetic acid. What do you observe See whether the protein solution is affected in the same way by sodium metaphosphate and acetic acid solutions taken separately. 

Pour a few drops of silver nitrate into a sodium metaphosphate solution. Note the colour of the precipitate. See how it reacts with dilute nitric acid. Write the equations of the reactions. In what medium can silver metaphosphate be precipitated ... 

SatnpCe Preparation. Seventy grams of sample, previously calcined at 538°C, was dispersed in about 125 mL of sodium metaphosphate solution and "wet screened" using a sieve stack of 250, 270 and 325 mesh, 8-inch diameter sieves. The sieves were washed with water until the effluent was free of any particulate and then rinsed with acetone to de-water. After air drying, the contents of each sieve were transferred to a porcelain dish and the material was recalcined at 538°C. Appropriate weights taken during this procedure allowed for the determination of percent moisture in the starting material and sieve analysis relative to the appropriate sieve fractions. The total +325 mesh material was recombined and mixed for the test. 

Into each of two test tubes put 5 c.c. of a solution of disodium orthophosphate and add to one a few drops of silver nitrate solution and to the other a few drops of calcium chloride solution. Kepeat the foregoing tests with the pyrophosphate and metaphosphate solutions prepared in (a) and (5). (2)... 

The monofluorophosphates can be prepared by neutralization of monofluorophosphoric acid (1). Sodium monofluorophosphate [7631 -97-2] is prepared commercially (57) by fusion of sodium fluoride and sodium metaphosphate, and the potassium monofluorophosphate [14104-28-0] can be prepared similarly. Insoluble monofluorophosphates can be readily prepared from reaction of nitrate or chloride solutions with sodium monofluorophosphate. Some salts are prepared by metathetical reactions between silver monofluorophosphate [66904-72-1] and metal chlorides. 

The earliest formulations, as reported by Rollins (1879), Gaylord (1889), Ames (1893), Hinkins Acree (1901) and Fleck (1902), were variously based on syrupy orthophosphoric acid or unstable mixtures of meta-phosphoric acid and sodium metaphosphate in solution. Some used solid pyrophosphoric acid. Many were grossly inferior cements which were hydrolytically unstable. 

The possible mechanisms for solvolysis of phosphoric monoesters show that the pathway followed depends upon a variety of factors, such as substituents, solvent, pH value, presence of nucleophiles, etc. The possible occurrence of monomeric metaphosphate ion cannot therefore be generalized and frequently cannot be predicted. It must be established in each individual case by a sum of kinetic and thermodynamic arguments since the product pattern frequently fails to provide unequivocal evidence for its intermediacy. The question of how free the PO ion actually exists in solution generally remains unanswered. There are no hard boundaries between solvation by solvent, complex formation with very weak nucleophiles such as dioxane or possibly acetonitrile, existence in a transition state of a reaction, such as in 129, or SN2(P) or oxyphosphorane mechanisms with suitable nucleophiles. 

The fact that the 3,P-NMR signal of 183a can only be observed in pyridine-containing solution provides food for thought124). Viewed in conjugation with the idea that alkyl metaphosphates could form adducts such as 173 and 174 U9,120) as discussed above, formulation as a zwitterionic pyridine/metaphosphate adduct (188) seems reasonable. Similar adducts have also been found in the reaction of TPS with dinucleotides and trinucleoside diphosphate 126). In any case, the reactions of 183 or 188 are in full accord with the expected properties of a monomeric metaphosphate and its reactivity towards alcohols is far greater than that of all other reactive phosphorylation intermediates which can arise on reaction of TPS with oligonucleotides 126). 

On the other hand, it is found that only partial racemization occurs on alkaline hydrolysis of optical active 198 in aqueous methanol136) and no racemization takes place in the hydrolysis of 199 in dioxane/water137). Moreover, the latter reaction is only ca. 80 times faster at 29 °C than that of the analogous morpholide 200, for which a metaphosphorimidate mechanism is precluded a priori by the absence of an NH function and whose hydrolysis is likewise stereospecific,37). Clearly a free metaphosphorimidothioate of type 191 cannot be involved in this case. The experimental findings are compatible, however, with the hypothesis that the nucleophile water attacks a metaphosphorothioimidate/phenolate associate 201. The question of how free metaphosphates occur in solution is of a general nature it has also been considered in the previous Section. 

During a search for high-energy phosphates, Ponnamperuma was able to synthesize adenosine triphosphate (ATP) from ADP, AMP or adenosine from ethyl metaphosphate in dilute aqueous solution under the influence of UV light. The role of the UV irradiation is unclear, as the phosphate itself is a high-energy species (Ponnamperuma et al., 1963). 

A second neutralization is carried out with soda ash to a pH level of about 4. Special heating, agitation, and retention are next employed to adequately condition the slurry so that filtration separation of the contaminants can be accomplished. The remaining solution is sufficiently pure for the production of monosodium phosphate, which can be further converted into other compounds such as sodium metaphosphate, disodium phosphate, and trisodium phosphate. A typical process flow diagram is shown in Figure 6. Wastewater effluents from these processes originate from leaks and spills, hltration backwashes, and gas scrubber wastewaters. 

Metaphosphate or POs . This ion, which is stable in the gas phase, is quickly converted to H2PO4 in aqueous solutions (note that the rate of conversion is slower at low temperatures). Metaphosphate has been postulated to be an intermediate in a number of enzyme-catalyzed reactions. See Metaphosphate... 

These neutralization processes may be used for the preparation of various complex fluorides without actually isolating the acid or the base. Thus, for example, if equivalent quantities of metallic silver and gold are dissolved in bromine trifluoride and all volatile material is removed in vacuum, the salt AgAuFg remains. The usefulness of this method is increased by the apparent existence in bromine trifluoride solution of both acids and bases which are not sufficiently stable to be isolated. This is well illustrated by the reaction of potassium metaphosphate with bromine trifluoride, which gives a quantitative yield of KPFg ... 

Anhydrous salt white crystalline powder slightly hygroscopic forms sodium acid pyrophosphate, Na2H2P20 on heating above 225°C and sodium metaphosphate (NaPOsln at about 350 to 400°C very soluble in water, aqueous solution acidic. 

POa)xx-. Contrary to the old nomenclature (340), which is still often used, they should no longer be designated as metaphosphates. Such a change in nomenclature is all the more important since the high-molecular polyphosphates in question differ clearly from true metaphosphates in that solutions of true metaphosphates have a neutral reaction since they are salts of strong acids those of polyphosphates are weakly acidic on account of the free OH end groups. In this review the term metaphosphate will be used only for condensed phosphates with cyclic anions. 

It seemed probable, from the early results of chromatography, that the hydrolyzate from Graham s salt contains metaphosphates with more than four phosphorus atoms in the anion ring 350). A little later 186) the metaphosphate content of a freshly prepared solution of Graham s salt with a mean chain length n of 100-125 was given as ... 

Unlike meta- and polyphosphates, cross-linked phosphates are unstable in aqueous solution in accordance with theoretical predictions (349), they are readily hydrolyzed at the positions where cross linking occurs and form mixtures of polyphosphates and metaphosphates (224, 84> 318). 

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