Polyphosphates, structure

G. Drews (1962). The cytochemistry of polyphosphates. In Proceedings ofAcides Ribonucleiques et Polyphosphates. Structure, Synthese et Fonctions, CNRS International Colloquim, Strasbourg, France, 1961, CNRS, Paris, pp. 533-539. 

In this chapter laboratory experiments will be discussed involving methods to prepare fibers with a polyphosphate structural framework. Since the anionic structure was selected for all systems under consideration, cationic types, ratios, thermal histories, seedings, and atmospheres dictate most of the variables that can be controlled. 

Oxygen chelates such as those of edta and polyphosphates are of importance in analytical chemistry and in removing Ca ions from hard water. There is no unique. sequence of stabilities since these depend sensitively on a variety of factors where geometrical considerations are not important the smaller ions tend to form the stronger complexes but in polydentate macrocycles steric factors can be crucial. Thus dicyclohexyl-18-crown-6 (p. 96) forms much stronger complexes with Sr and Ba than with Ca (or the alkali metals) as shown in Fig. 5.6. Structural data are also available and an example of a solvated 8-coordinate Ca complex [(benzo-l5-crown-5)-Ca(NCS)2-MeOH] is shown in Fig. 5.7. The coordination polyhedron is not regular Ca lies above the mean plane of the 5 ether oxygens... 

Chain metasilicates Si03 formed by comersharing of Si04 tetrahedra arc particularly prevalent in nature and many important minerals have this basic structural unit (cf, polyphosphates, p, 528), Despite the apparent simplieily of their structure motif and stoichiometry considerable structural diversity is encountered because of the differing conformations that can be adopted by the linked tetrahedra. As a result, the repeat distance along the c -axis can be (1). 

A rather different structure-motif is observed in the chain polyphosphates these feature comer-shared PO4 tetrahedra as in the polyphosphoric acids (p. 522). The general formula for such anions is [Pn03 4.i] + , of which the diphosphates, P2O7 ", and tripolyphosphates, PsOjo , constitute the first two members. Chain polyphosphates have been isolated with n up to 10 and with n infinite , but those of intermediate chain length (10 < n < 50) can only be obtained as glassy or amorphous mixtures. As the chain length increases, the ratio (3n + l)/n approaches 3.00 and the formula approaches that of the polymetaphosphates [P03 ]oo-... 

Fuller treatments of the phase relations and structures of polyphosphates, and their uses as glasses, ceramics, refractories, cements, plasters and abrasives, are available. 

The higher elastic modulus (a measure of structure in solution) of rhamsan suggests that it should be superior to xanthan as a stabiliser. Rhamsan also has improved salt compatibility and is used in fertiliser suspension (high polyphosphates) and explosives (high ammonium nitrate). 

Orthosilicates are not suitable for corrosion inhibitor purposes, and metasilicates are not generally used because they tend to increase the caustic alkalinity too much, leading to the potential for caustic-induced problems. However, glassy polysilicates are widely used. They have inhibition properties similar to those of polyphosphates and also have an indefinite crystalline structure. 

Figure 10.1 Types of phosphate structures, (a) Where x = 12 to 14, the structure represents sodium polyphosphate, a phosphate typically used in HW heating and industrial steam boiler formulations. The structure is ill defined and described as glassy rather than crystalline. Where x = 2, it represents sodium tripolyphosphate, (b) This is the structure where effectively, x = 0, and represents trisodium phosphate (sodium orthophosphate), which is commonly supplied in either crystalline or anhydrous powder form and used as an alkalinity booster, boiler boil-out cleaner, and metal surfaces passivator.

P406 and P4Ow are the anhydrides of phosphorous acid and phosphoric acid, respectively. Polyphosphates are extended structures used (as ATP) by living cells to store and transfer energy. 

Klosinski, P., Penczek, S. Teichoic Acids and Their Models Membrane Biopolymers with Polyphosphate Backbones. Synthesis, Structure and Properties. Vol. 79, pp. 139-157. 

The presence of inorganic polyphosphate in electron-dense particulate structures of M. luteus has been demonstrated by n.m.r., confirming an earlier observation based on chemical techniques. ... 

The adverse effect of nonionic adducts of low cloud point can be avoided by the use of hybrid agents of the ethoxylated anionic type, variously and confusingly referred to as modified nonionic , modified anionic or weakly anionic types. Thus Mortimer [113] has proposed the use of products of the ethoxylated phosphate type (12.27). In this structure, R, as well as the degree of ethoxylation (n) may be varied to optimise the overall HLB value. The numerous ether groups are said to enhance the dye-solubilising and levelling capacity, whilst the polyphosphate grouping exerts several useful effects [113]. These compounds ... 

The experimental weight loss in the first and second step (4.0 and 4.5% respectively) is in agreement with that corresponding to condensation to pyrophosphate (4.0%) and polyphosphate (4.2X, n 1). Furthermore, the IR spectra of melamine phosphate and of the residues at 300 and 330 C (Figure 14 spectra A, B and C respectively) show that besides the typical bands of phosphate salts (950-1300 cm-1) which are present in the three spectra, a new absorption due to P-O-P bonds (ca. 890 cm-1) appears in the spectra of the residues. The absorptions due to melamine salt structures (e.g. 780-790 and 1450-1750 cm ) are closely similar in the three spectra of Figure 14. Fire retardants based on melamine pyrophosphate and polyphosphate are reported in the literature 51 as well as methods for preparation of these salts (25-... 

Moreover, simultaneous evolution of water implies that condensation of melamine is combined with that of polyphosphoric structures. Assuming the reaction scheme proposed above, melam polyphosphate and ammonium polyphosphate groups should be formed from melamine polyphosphate ... 

It is known that ammonium polyphosphate tends to dissociate liberating ammonia above 300 C and the resulting free hydroxy groups condense giving crosslinked structures (ultraphosphate) with elimination of water (28.29) ... 

The general formula of these new oxynitrides M2M1(PX3)3 suggests as for the previous series a cyclophosphate-type structure or a long-chain polyphosphate-type structure, where nitrogen would be structurally equivalent to oxygen. 

Polymers having ionisable groups along the chain are known as polyelectrolytes. They generally exhibit properties in solution which are quite different from those with non-ionisable structures. Examples of polyelectrolytes include polyacids like poly (acrylic acid) and hydrolysed copolymers of maleic anhydride, polybases like poly (vinyl amine) and poly (4-vinyl pyridine), polyphosphates, nucleic acids, and proteins. 

Coenzymes complement the catalytic action of the amino-acid functional groups. They are bound to apoenzymes (apoproteins) either covalently or non-covalently. It is interesting to note that non-covalently-bound coenzymes are polyanions at neutral pH as exemplified by the structures of glutathione (GSH) [17] and thiamine pyrophosphate [18]. Shinkai and Kunitake (1976b, 1977a) demonstrated the efficient binding of glutathione and coenzyme A (a polyphosphate) to cationic micelles and cationic polysoaps. Thus, the combina- ... 

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