Metaphosphate trimetaphosphates

The only tme metaphosphate (ring stmcture) of significant commercial interest is sodium trimetaphosphate (STMP), Na P O. Because of the strain inherent in the small ring stmcture, STMP is more reactive toward nucleophiles than chain phosphates. In the presence of NaOH, for example, STMP forms sodium tripolyphosphate. 

Chemical Designations - Synonyms Sodium phosphate is generic term and includes the following (1) monosodium phosphate (MSP sodium phospWe, monobasic), (2) disodium phosphate (DSP sodium phosphate dibasic), (3) trisodium phosphate (TSP sodium phosphate, tribasic), (4) sodium acid pyrophosphate (ASPP SAPP disodium pyrophosphate (TSPP), (6) sodium metaphosphate (insoluble sodium metaphosphate), (7) sodium trimetaphosphate, and (9) sodium tripolyphosphate (STPP TPP) Chemical Formula (1) NaHjPO (2) Na HPO (3) NajPO (4) Na H P O, (5) Na P O, (6) (NaPOj) (7) (NaP03)3 (8) (NaP03) NaO (9) Na,P30,o. 

On use of N,N -dicyclohexylcarbodiimide instead of sulfonyl chlorides as condensation reagent in oligonucleotide synthesis, then the pyro-, tri- and tetraphosphate stages are again involved 124). The metaphosphate 183 a is found in small amounts by 3iP-NMR spectroscopy, but again no cyclic trimetaphosphate 184 can be detected, which would also be a possible phosphorylation reagent. 

Sodium Trimetaphosphate occurs as white crystals or as a white, crystalline powder. It is a cyclic polyphosphate composed of three metaphosphate units. It is freely soluble in water. The pH of a 1 100 aqueous solution is about 6.0. 

In the discussion to follow, the great differences between sodium and potassium condensed phosphate phase systems is highlighted. Where the sodium Kurrol s salt is metastable with respect to the cyclic sodium trimetaphosphate there is no cyclic metaphosphate in the potassium phosphate two component phase system and the Kurrol s salt is the only stable compound in the phase system with K2O-P2O5 ratios near unity. 

The sodium polyphosphate systems produce glasses very easily while it is difficult to make potassium glasses. The milky glassy masses of potassium metaphosphate compositions obtained by quenching the potassium melts are rich in potassium trimetaphosphate, though the phase diagram for the system contains none. Potassium cyclic triphosphate can be made thermally by dehydrating monopotassium orthophosphate with urea at temperatures less than 300 C,... 

Maddrell s salt, which are interpreted as showing that kinetic effects are responsible for difficulties in converting the cyclic trimer into the linear polymeric forms. The potassium polyphosphate samples (Kurrol s salt) obtained from the fusion of potassium sulphate and phosphoric acid have chains terminated by OSOJ groups, according to i.r. spectra. Kinetic studies show a first-order dependence of polyphosphate concentration in the hydrolysis of Graham s salt to give trimetaphosphate and short-chain species. The vaporization of sodium metaphosphate from a Knudsen cell leads to predominantly monomeric, with some dimeric, species, according to mass-spectrometric data. ... 

Since a melt having a composition of sodium metaphosphate is crystallized as sodium trimetaphosphate under the same conditions as those used for the preparation of the crystals of sodium vanadate-phosphates, it is easy to surmise that crystals with P/V ratios of 7, 10, and 50 are mainly composed of trimetaphosphate, as shown in Table XVII. With a decreasing P/V ratio, i.e., with an increase in the absolute amount of vanadium, the amount of trimetaphosphate decreases and that of diphosphate increases. Moreover, the diphosphate found in the... 

A further study by Ramirez et al. (1982) also utilized the effect of solvent and ionic state in controlling reactivity patterns. A number of reactions, including the decomposition and nucleophilic substitution processes of p-nitrophenyl phosphate in acetonitrile, were examined. In the absence of added nucleophiles cyclic trimetaphosphate is produced. Both t-butyl alcohol and phenol are phosphorylated under these conditions. A nonaqueous solvent of low polarity should be better than water in promoting the conversion of the highly ionic product to the less polar transition state that would produce metaphosphate. The low steric sensitivity of the reaction and the increased rate of the dianion relative to the monoanion are consistent with either any extended associative transition state or the dissociative transition state. Stereochemical studies of these reactions by Knowles... 

Ciassification Food starch modified Definition Prod, from crosslinking of starch with sodium metaphosphate, sodium trimetaphosphate, or phosphorus oxychloride Properties Wh. or nearly wh. powd. or gran. flakes, amorphous powd. or coarse particles if pregelatinized... 

Sodium metaphosphate Sodium phosphate Sodium phosphate tribasic Sodium sesquicarbonate Sodium silicate Sodium trimetaphosphate Strontium hydroxide Succinic acid Sulfuric acid D-Tartaric acid... 

Sodium trimetaphosphate can be prepared by (1) heating sodium dihydrogen orthophosphate for 5 hours at 530° or (2) tempering a glassy sodium metaphosphate at 520° fo 12 hours. If the product obtained by the first of these procedures is not entirely water-soluble, additional heating will be necessary to eliminate the insoluble polymer that forms at a lower temperature. 

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