Long-Chain Polyphosphates

A polyphosphate is usually termed long chain when it contains more than about 50 tetrahedra, although the average value of n usually lies in the range 500-10,000 in most salts of this type. Individual crystalline varieties of the long-chain polyphosphates contain a distribution of chain lengths, but the chains are all so long and similar in their properties that these varieties are, for all practical purposes, pure compounds rather than mixtures [3]. 

In older literature, long-chain polyphosphates are not infrequently referred to as metaphosphates because they have approximately the same composition. The latter term should, however, be reserved for cyclic anions which have the exact composition (POj) . Although aU high-molecular-weight polyphosphates approximate to the metaphosphate composition (n + 1 — n when n is large), such chains are usually terminated by OH groups and their correct formulation is 

The average chain length resulting from a given preparation can be considerably influenced by the availability of stopper OH groups. The water vapour pressure existing over a supposedly anhydrous melt is known to influence chain length in this way. 

If sodium dihydrogen orthophosphate is heated below 240°C, only the acid pyrophosphate, Na2H2P207, is produced. On heating above 240°C, this salt may be changed to a long-chain material known as Maddrell salt [44] (two polymorphic forms), or to sodium trimetaphosphate, NajPjOg. These two compounds are typical of the variety of polyphosphates and metaphosphates which exist 

The material is obtained in the form of characteristically long fibrous needles, each containing polyphosphate chains lying in the direction of the fibre axis. Kurrol and Maddrell salts are both high-molecular-weight polyphosphates which exhibit the properties of high polymers. Both are insoluble in water and hydrolyse relatively slowly, although Kurrol salt will dissolve in the presence of different alkali metal cations. 

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Condensed phosphates are derived by dehydration of acid orthophosphates. The resulting polymeric stmctures are based on a backbone of P—O—P linkages where PO tetrahedra are joined by shared oxygen atoms. The range of materials within this classification is extremely broad, extending from the simple diphosphate, also known as pyrophosphate, to indefinitely long-chain polyphosphates and ultraphosphates (see Table 1). Both weU-defined crystalline and amorphous materials occur among the condensed phosphates. 

Sodium tripolyphosphate is produced by calcination of an intimate mixture of orthophosphate salts containing the correct overall Na/P mole ratio of 1.67. The proportions of the two anhydrous STP phases are controlled by the calcination conditions. Commercial STP typically contain a few percent of tetrasodium pyrophosphate and some trimetaphosphate. A small amount of unconverted orthophosphates and long-chain polyphosphates also may be present. 

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. 

See also van der Waals forces Long-chain aliphatic acids, 20 97 Long chain amphiphiles, 24 123 Long-chain branching, 19 840 extent of, 19 839 in HDPE, 20 160-162 in LDPE, 20 220, 232-234 in LDPE resins, 20 215 quantifying, 20 228-229 Long-chain polyphosphates,... 

A Gel Chromatographic Study on the Interactions of Long-Chain Polyphosphate Anions with Magnesium Ions... 

In spite of much information available for the interactions of various metal ions with small oxoanions of phosphorus, relatively little information has been obtained for the complex formation of long-chain polyphosphate ion. This may be due to the fact that the conventional methods useful for the study of the complex formation of a relatively small ligand are not always applicable to the polyanion complex formation system. Since a gel chromatographic method based on the same principle as the equilibrium dialysis method has been proved to be applicable in the field of inorganic complex chemistry (1), this method has been applied to the study of the binding of long-chain polyphosphate ions to magnesium ion. 

This work was undertaken in order to evaluate the binding of middle units of long-chain polyphosphate to magnesium ion from a view point of the mass action law. 

As a result of tribochemical reactions and the presence of oxygen or hydroperoxide in oil, adsorbed ZDDP and LI-ZDDP on the surface are thermo-oxidatively decomposed to give long-chain polyphosphates Zn(P03)2. 

ZDDP tribofilms are composed of inorganic polymer material on the top surface the long chain polyphosphate is a zinc phosphate and in the bulk the short chain polyphosphate is a mixed Fe/Zn phosphate with a gradient concentration. 

EXAFS Tribofilms were amorphous with long-chain polyphosphates with Fe as the cation (Belin et al., 1989 and 1995 Martin et al., 1986a). 

A recent XANES experiment showed that the ZDDP tribofilm generally has a two-layer structure a short-chain phosphate layer covered by a thin, long-chain polyphosphate layer. XANES spectra analysis of tribofilms did not show a substantial difference between neutral and basic ZDDPs (Fuller et al., 1997 Martin, 1999 Martin at al., 2001 Varlot et al., 2000 Willermet et al., 1991 and 1992 Yamaguchi et al., 1993 and 1996). 

At lower temperature, thermally generated film has more similarity to tribofilm. The thermal films, as in the case of the tribofilms, contain mostly a mixture of short-and long-chain polyphosphates. The chemical states of phosphorus and sulfur in each neutral and basic pair were very comparable. The aryl phosphate films contain long-chain polyphosphate throughout the film, whereas the alkyl phosphate films are composed of long-chain polyphosphates in the bulk. Also, the aryl polyphosphate films contain more unchanged ZDDP. 

Thermal film in oil solution Mixture of short and long chain polyphosphates. Sulfur is absent at 200°C present as sulfate at low temp. Mixture of polyphosphates. Above 200°C, sulfur is absent in the film present as sulfate at low temp. Mixture of polyphosphates. Above 200°C, sulfur is absent in the film present as sulfate at low temp. 

Tribochemical film in oil solution Long chain polyphosphate on the topmost surface and short chain polyphosphates in the bulk. S is present as sulfide. Long chain polyphosphate on the topmost surface and short chain poly-phosphates in the bulk. S is present as sulfide. Long chain polyphosphate throughout the tribofilm. Contain more unchanged ZDDP. 

The ZDDP oil solution produced a long-chain polyphosphate tribofilm whereas the corresponding disulfide (no zinc present) yielded a simple phosphate antiwear film (Kasrai et al., 1994). The effect of zinc in the antiwear agent is very significant. The chemical nature of sulfur and phosphorus, in the films of isopropyl DDP (without zinc), is quite different from those with zinc. When zinc is present, phosphate in the film tends to polymerize more, and zinc acts as an antioxidant for sulfur in protecting the sliding surfaces. 

The chain lengths in FY spectra are estimated at 12, 7 and 1 in for 0.5 wt%, 1 wt.% and 2 wt% calcium phenate, respectively. Thus the topmost surface measured by TEY contains relatively long chain polyphosphates, and the bulk chemistry of the film measured by FY contains mostly shorter chain polyphosphates. The bulk FY signal is relatively strong, indicating that the films formed with calcium phenate are relatively thick (several hundred angstroms). Summary of the tribofilm compositions is displayed in Table 4.4. The (S) L-edge... 

PROCESSES The two surfaces may contact each other. Elastic and plastic deformation. Frictional heat. Wear. EXOEMISSION Triboemission (radicals, electrons, photons, positive ions, X-ray emission). After-emission electrons. STRUCTURE Upper layer long chain polyphosphates. Lower layer short chain polyphosphates. 

J. J. Blum (1989). Changes in orthophosphate, pyrophosphate and long-chain polyphosphate levels in Leishmania major promastigotes incubated with and without glucose. J. Protozool., 36, 254-257. 

J. E. Clark and H. G. Wood (1987). Preparation of standards and determination of sizes of long-chain polyphosphates by gel electrophoresis. Anal. Biochem., 161, 280-290. 

S. Felter, G. Dirheimer and J. P. Ebel (1968). Fractionation of inorganic long-chain polyphosphates... 

K. D. Kumble and A. Kornberg (1996). Endopolyphosphatases for long chain polyphosphate in yeast and mammals. J. Biol. Chem., 271, 27146-27151. 

S. K. Maier, S. Scherer and M. J. Loessner (1999). Long-chain polyphosphate causes cell lysis and inhibits Bacillus cereus septum formation, which is dependent on divalent cations. Appl. Environ. Microbiol., 65, 3942-3949. 

S. Ohashi and J. R. Van Wazer (1964). Paper chromatography of very long chain polyphosphates. Anal. Chem., 35, 1984-1996. 

S 24 Strauss, U. F., and P. L. Wineman Molecular dimensions and interaction of long chain polyphosphates in sodium bromide solutions. J. Am. Chem. See. 80, 2366 (1958). 

The rise in pK pp with a is unexpected because there is no reason to expect the nonidedity characteristics of the a/(l - a) and [Hjg terms in Eq. (25) to change as drastically as this result would appear to imply. As a consequence, the unexpected rise in pK pp has to be attributed to overestimate of Vg in the course of its measurement. Such a possibility has been attributed to the si2able macroporosity of the C-50 gel. Apparently, long-chain polyphosphate ions, the macromolecule used to monitor solvent uptake by the gel [43] through its concentration change in salt solution used to equilibrate with accurately weighed bone dry C-50 samples... 

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