Phosphate orthophosphate

The most general method for the simultaneous analysis of oxyanions by gas chromatography is the formation of trimethylsilyl derivatives. Trimethylsilyl derivatives of silicate, carbonate, oxalate, borate, phosphite, phosphate, orthophosphate, arsenite, arsenate, sulfate and vanadate, usually as their ammonium salts, are readily prepared by reaction with BSTFA-TMCS (99 1). Fluoride can be derivatized in aqueous solution with triethylchlorosilane and the triethylfluorosilane formed extracted into an immiscible organic solvent for analysis by gas chromatography [685). 

In the Codex Alimentarius a number of further sequestrants and antioxidant synergists are issued which also pertain to the group of antioxidants. The main representatives of sequestrants are acetates, citrates, tartrates, phosphates, orthophosphates, diphosphates, triphosphates, and polyphosphates, esters of glycerol, sorbitol and sorbitol syrup, gluconates, and 1,4-heptonolactone. Lactates and tartaric acid are considered as antioxidant synergists. The spectrum... 

Adsorption inhibitors act by forming a film on the metal surface. The action of traditional oil-based red lead paint formulations presumably involves the formation of soaps and the precipitation of complex ferric salts that reinforce the oxide film. There has been substantial interest in recent years in development of replacements for lead-based and chromate-based inhibitor systems. Adsorption inhibitors based on pol3rmers have been of particular interest. In this volume, Johnson et al. and Eng and Ishida discuss inhibitors for copper 2-undecylimidazole is shown to be effective in acid media, where it suppresses the oxygen reduction reaction almost completely. Polyvlnyllmidazoles are shown to be effective oxidation inhibitors for copper at elevated temperatures. Also in this volume, Chen discusses the use of N-(hydroxyalkyl)acrylamide copolymers in conjunction with phosphate-orthophosphate inhibitor systems for cooling systems. 

These reactions are reversible, and removal of the caustic alkali by addition of acids effects the immediate conversion of ortho- or pyro-salts into the meta-salts. On the other hand, the presence of a large excess of caustic alkali favours the formation of the ortho- and pyro-salts. The order of stability is the reverse of that which applies to the ortho-, pyro-, and meta-phosphates. Orthophosphates are prepared from the other two classes either by boiling or by addition of weak acids. 

Orthophosphoric Dihydrogen phosphate Monohydrogen phosphate Orthophosphate acid anion anion anion... 

APP is a stable, nonvolatile material. It slowly hydrolyzes in contact with water to produce monoammonium phosphate (orthophosphate). This process is autocatalytic and is accelerated by higher temperatures and prolonged exposure to water. The decomposition temperature of APP is related to the length of the polymer chain. Long-chain APP starts to decompose at temperatures above 300 °C to polyphosphoric add and ammonia. Short-chain APP, defined as that having a chain length below 100 monomer units, begins to decompose at temperatures above 150°C. 

In the world of phosphates, orthophosphates and polyphosphates are asymmetric in their properties. Orthophosphates are a single center radical, with sp hybridized bonding, and there are three levels of cationic attraction to the group. This influence is most pronounced with hydrogen ions showing extremely different pKs. 

The above is a general procedure for preparing trialkyl orthophosphates. Similar yields are obtained for trimethyl phosphate, b.p. 62°/5 mm. triethyl phosphate, b.p. 75-5°/5 mm. tri-n-propyl phosphate, b.p. 107-5°/5 mm. tri-Mo-propyl phosphate, b.p. 83-5°/5 mm. tri-wo-butyl phosphate, b.p. 117°/5-5 mm. and tri- -amyl phosphate, b.p. 167-5°/5 mm. The alkyl phosphates are excellent alkylating agents for primary aromatic amines (see Section IV,41) they can also be ua for alkylating phenols (compare Sections IV,104-105). Trimethyl phosphate also finds application as a methylating agent for aliphatie alcohols (compare Section 111,58). 

Orthophosphate Hquid mixtures are ineffective as micronuttient carriers because of the formation of metal ammonium phosphates such as ZnNH PO. However, micronutrients are much more soluble in ammonium phosphate solutions in which a substantial proportion of the phosphoms is polyphosphate. The greater solubiHty results from the sequestering action of the polyphosphate. The amounts of Zn, Mn, Cu, and Fe soluble in base solution with 70% of its P as polyphosphate are 10 to 60 times their solubiHties in ammonium orthophosphate solution. When a mixture of several micronutrients is added to the same solution, the solubiHty of the individual metals is lowered significantly. In such mixtures the total micronuttient content should not exceed 3% and the storage time before precipitates appear may be much shorter than when only one micronuttient is present. 

Melamine and Other Amine Phosphates. Three melamine phosphate commercial products have been reported (60) including melamine orthophosphate [20208-95-17, H O P, [41583-09-9] aH O P dimelamine orthophosphate and melamine pyrophosphate [15541-60-3] ... 

Phospha.tes. Many phosphates cl aim unique material advantages over siUcates that make them worth the higher material costs for certain apphcations. Glass-ceramics containing the calcium orthophosphate apatite, for example, have demonstrated good biocompatibiUty and, in some cases even bioactivity (the abiUty to bond with bone) (25). Recent combinations of fluorapatite with phlogopite mica provide bioactivity as well as machinability and show promise as surgical implants (26). 

In internal or bulk settiag, which is normally carried out at room temperature, the calcium is released uader coatroUed coaditioas from within the system. This method led to the developmeat of stmctured fmits, stmctured pet foods, and a host of cold prepared desserts. Calcium sulfate (usually as the dihydrate) and dicalcium phosphate (calcium hydrogen orthophosphate) are the sources of calcium most commonly used. 

Nickel Phosphate. Tri nickel orthophosphate [14396-43-17, Ni2(P0 2 7H20, exists as apple-green plates which decompose upon heating. It is prepared by the reaction of nickel carbonate and hot dilute phosphoric acid. Nickel phosphate is an additive to control the crystal size of ziac phosphate ia coaversioa coatiags which are appHed to steel prior to its being paiated (see Metal surface treatments). 

Phosphoric acids and the phosphates maybe defined as derivatives of phosphoms oxides where the phosphoms atom is in the +5 oxidation state. These are compounds formed in the M2O—P20 system, where M represents one cation equivalent, eg, H", Na", 0.5 Ca ", etc. The molecular formula of the phosphoms(V) oxide [1314-56-3] is actually P O q, but this oxide is commonly referred to in terms of its empirical formula, P2O5. StmcturaHy, four phosphoms—oxygen (P—O) linkages are arranged in an approximate tetrahedral configuration about the phosphoms atom in the phosphate anion. Compounds containing discrete, monomeric PO ions are known as orthophosphates or simply as phosphates. 

Orthophosphate salts are generally prepared by the partial or total neutralization of orthophosphoric acid. Phase equiUbrium diagrams are particularly usehil in identifying conditions for the preparation of particular phosphate salts. The solution properties of orthophosphate salts of monovalent cations are distincdy different from those of the polyvalent cations, the latter exhibiting incongment solubiUty in most cases. The commercial phosphates include alkah metal, alkaline-earth, heavy metal, mixed metal, and ammonium salts of phosphoric acid. Sodium phosphates are the most important, followed by calcium, ammonium, and potassium salts. 

The solubihty of a number of sodium orthophosphates is depicted in Figure 7. Some of the sodium phosphates dissolve or precipitate incongmendy, affording a different Na20/P20 ratio in the solution phase from that of the soHd phase. Sodium phosphates that precipitate are also a function of the temperature. As the temperature increases, the sodium phosphates that may precipitate from solution tend to be anhydrous or lower hydrates than those equiUbrium sodium phosphate phases at lower temperature. Whereas most of the phases in Figure 7 represent congmentiy soluble sodium phosphates, soHd phases appear or disappear upon changes in temperature. 

---