Metaphosphates preparation

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. 

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. 

They can also be prepared in specialized cases by (a) metathesis, (b) the action of H7PO4 on an oxide, (c) thermolysis of a metaphosphate, (d) thermolysis of an orthophosphate, or (e) reductive thermolysis, e.g. ... 

Niecke et al. have prepare polyimido analogues of the metaphosphate ion, PO3, bylithiation ofthe corresponding amido compounds [16]. Thus the monomeric solvent-separated ion pair [(THF)4Li][P(NMes )3] (10) is obtained by treatment of (Mes N)2P(NHMes ) with "BuLi [16]. A monomeric contact ion pair (11) containing the unsymmetrical anion [P(N Bu)2(NMes )]" has also been reported [16]. By contrast the dilithium derivative of the trisimidometaphosphate [P(N Bu)3]" forms a dimer (12) [17], with a cubic structure reminiscent of that of (7). 

By contrast to the metaphosphimates, the metaphosphate analogues in which two chalcogens are replaced by imido groups form dimeric, dianionic ligands (24). There is only one example of a metal complex of the oxo system (24, E = O). An N,0-chelated bis(dimethylalumimun) complex is prepared by the reaction of two equivalents of trimethylaliuninum with ds-[ BuNH(0)P(//-N Bu)2P-(0)NH Bu] [20]. The structure of this complex is comparable to that of (15). 

It is still unclear how much general validity attaches to the metaphosphate mechanism as formulated for the present variant for the oligonucleotide synthesis. Depending upon the reaction conditions, preparative method, activating reagent, and length of the nucleotide block, other mechanisms may dominate. 

Miller and Parris (1964) pointed out that the preparation of ethyl metaphosphate from P2O5, diethyl ether and chloroform could hardly be considered "prebiotic this criticism is certainly irrefutable ... 

Metaphosphates have been prepared by the action of phosphoric anhydride on dry ether and also by metathesis 1... 

Earlier claims for the preparation of methyl metaphosphate, if only in situ, have received further support by the observation that the species, thought to be (119), will attack AW-diethylaniline at low temperatures to give methyl 4-AW-diethylamino-phenylphosphonate.89 The formation of 005-triethyl phosphorodithioate together with triethyl thionoformate when triethyl orthoformate is treated with P2S5 or diethyl hydrogen dithiophosphate is interpreted in terms of the species (120).00... 

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 ... 

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 ... 

Whey protein concentrates (WPC), which are relatively new forms of milk protein products available for emulsification uses, have also been studied (4,28,29). WPC products prepared by gel filtration, ultrafiltration, metaphosphate precipitation and carboxymethyl cellulose precipitation all exhibited inferior emulsification properties compared to caseinate, both in model systems and in a simulated whipped topping formulation (2. However, additional work is proceeding on this topic and it is expected that WPC will be found to be capable of providing reasonable functionality in the emulsification area, especially if proper processing conditions are followed to minimize protein denaturation during their production. Such adverse effects on the functionality of WPC are undoubtedly due to their Irreversible interaction during heating processes which impair their ability to dissociate and unfold at the emulsion interface in order to function as an emulsifier (22). 

Ammonium metaphosphates.—The product obtained by H. N. Stokes6 by boiling monamidophosphoric acid, NHa.PO(OH)2, is either ammonium mono-metaphosphate, or a mixture of different metaphosphates—vide infra. G. Tam-mann prepared microscopic crystals of what he called ammonium /3-monometa-phosphate, NH4P08, by crystallization in the cold of a soln. of phosphorus pentoxide and glassy metaphosphoric acid with ammonium carbonate. A soln. of the purified salt gives a white precipitate with silver nitrate. The air-dried salt has the composition NH4P03.3,4H2O and it passes in a few weeks into the orthophosphate. 

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