Trivalent phosphoric acid

The Arbuzov reaction,also called the Michaelis-Arbuzov reaction, allows for the synthesis of pentavalent alkyl phosphoric acid esters 4 from trivalent phosphoric acid esters 1 (Z,Z = R,OR) by treatment with alkyl halides 2. 

Examples of the synthesis of phosphite and phosphate esters of sugars are included in a review on trivalent phosphorous acids (Scheme 5). The synthesis of an oxyphosphorane has also been reported (Scheme 6). A strategy for regioselective phosphorylation of aldoses in aqueous solution involves reversible attachment of activated diamidophosphate (DAP). The carbonyl addition prod-... 

The use of silver (II) salts, particularly argentic picolinate, as reagents for hydroxyl oxidation has also been disclosed recently. The reaction may be run in acid, neutral or basic media in aqueous or polar organic solvents at room or slightly elevated temperatures. Primary alcohols may be oxidized to aldehydes or acids depending on the conditions used. Amines and trivalent phosphorous compounds are more sensitive to oxidation with this reagent than are hydroxyl groups. 

The intracellular and plasma membranes have a complex structure. The main components of a membrane are lipids (or phospholipids) and different proteins. Lipids are fatlike substances representing the esters of one di- or trivalent alcohol and two aliphatic fatty acid molecules (with 14 to 24 carbon atoms). In phospholipids, phosphoric acid residues, -0-P0(0 )-O-, are located close to the ester links, -C0-0-. The lipid or phospholipid molecules have the form of a compact polar head (the ester and phosphate groups) and two parallel, long nonpolar tails (the hydrocarbon chains of the fatty acids). The polar head is hydrophihc and readily interacts with water the hydrocarbon tails to the... 

Act to decompose hydroperoxides into stable molecules such as alcohols and ethers, before they can react with light to form free radicals. Main chemical classes are trivalent phosphorous compounds and thio-synergists (esters of thiodipropionic acid). Sulfur-based organic antioxidants decompose hydroperoxides by non-radical reactions. Typical peroxide decomposers are Irgafos 168, Ultranox 626, Irganox PS 800 and others. 

The addition of finely dispersed solid particles improves the IR absorption of the polymer and positively influences blowing of the preforms. Such solid particles can be obtained by the reduction of Sb3+ to metallic antimony during polycondensation by the addition of trivalent phosphorous compounds such as phosphonic acid or its esters (phosphites). However, only a slight improvement in properties could be achieved by this approach [35],... 

There are various types of organic proton exchangers (34, 35, 38). Diesters of phosphoric acid, (RO)2P = 0(0H), phosphonic acids, R(RO)P = 0(0H), and phos-phinic acids, R2P = 0(0H), where R represents linear or branched alkyl or phenyl substituents, are the most common cation exchangers developed in liquid-liquid extraction for the extraction of trivalent 4/and 5/elements. They were initially developed for the American TALSPEAK and the Japanese DIDPA processes and have recently been introduced in the French DIAMEX-SANEX process. As for previously described NOPCs, these organophosphorus acids present oxygen-donor atoms (hard bases) in their structures and therefore will easily coordinate trivalent lanthanide and actinide cations, but they will not allow complete discrimination of the two families of elements. However, contrary to previously described neutral organophosphorus... 

The ZEALEX Process Researchers from KRI have shown that the zirconium salt of dibutyl phosphoric acid (ZS-HDBP) was soluble in Isopar-L in the presence of 30% TBP. This super PUREX solvent, known as ZEALEX, extracts actinides (Np-Am) together with lanthanides and other fission products, such as Ba, Cs, Fe, Mo, and Sr from nitric acid solutions. The extraction yields depend on both the molar ratio between Zr and HDBP in the 30% TBP/Isopar-L mixture and the concentration of HN03 (232). Trivalent transplutonium and lanthanide elements can be stripped together from the loaded ZEALEX solvent by a complexing solution, mixing ammonium carbonate, (NH4)2C03, and ethylenediamine-N.N.N. N -tetraacetic acid (EDTA). An optimized version of the process should allow the separation of... 

Di(2-ethylhexyl) phosphoric acid, used in the TALSPEAK process, which extracts trivalent metallic cations at low acidity by proton exchange. 

Separation of Pu From Am and Cm by HDEHP - Plutonium(IV) can be extracted by HDEHP (di-(2-ethylhexyl) phosphoric acid) from nitric acid of medium concentration trivalent TPE and some other impurities are not extracted. 

Phosphoric acid is a co-ordinated compound with the co-ordination number 4, and may accordingly be written H3[P04] (see section on Phosphorus in Combination ). Although the trivalent ion seldom is actually present, except perhaps in solid Na3P04, etc., it is written... 

Aluminum oxide is the only trivalent oxide that has been used to form a ceramic some heat treatment is needed. Kingery claims to have observed a setting reaction between trivalent iron oxide and phosphoric acid, but this reaction may have been caused by traces of magnetite in the trivalent oxide. Pure trivalent iron oxide such as hematite (Fe203) does not react with phosphoric acid. Overall, trivalent metal oxides have a solubility that is only marginal and falls below that of even sparsely soluble divalent oxides, while the solubility of oxides of most quadrivalent metals (zirconium is an exception) is too low to form a ceramic. 

In Table 1, typical extracting reagents used for separation and enrichment of inorganic elements are summarized. Organophosphorus extractants are often used because of their solubility properties. Di(2-ethylhexyl) phosphoric acid is commonly applied to industrial separations because of its high extractability and high separation factors between many inorganic elements, especially for rare earth elements. Other metal ions are extracted as well as the trivalent metal ions. 

Mitsunobu, O., Yamada, M., Mukaiyama, T. Preparation of esters of phosphoric acid by the reaction of trivalent phosphorus compounds with diethyl azodicarboxylate in the presence of alcohols. Bull. Chem. Soc. Jpn. 1967,40, 935-939. 

The addition of an ether linkage in the alkyl chains of dialkylphosphoric acids has been found to increase its extractive power for trivalent actinides, resulting in an extractant that is more effective from acid solutions than is HDEHP (69). Bis(hexoxy-ethyl)phosphoric acid (HDHqEP) is a compound of this type that has been studied extensively (70,71). The ether linkage may contribute to the coordination of the metal ion, resulting in the formation of a seven-membered ring. 

In the Talspeak process, the separation of trivalent actinides and lanthanides is accomplished by coextracting the two groups of elements into di(2-ethyl hexyl)phosphoric acid (HDEHP) from a carboxylic acid solution and then partitioning the acti-... 

Unprecedented high protonic conductivities, of 0.1-0.2 S cm at 200-350 °C in unhumidified air, were recently reported [308, 309] for SnP2O7 with trivalent dopants (Al or In). The published formulas, Sni-xM + PzO . are, however, not charge-balanced, and the presence of x protons is implied. It is likely that the observed high conductivities might be due to residual liquid phosphoric acid used in excess for the synthesis these materials require careful re-examination. 

Like the elements, the radicals possess different valences, depending upon the number of unsatisfied valences which they contain. Thus the radical (CH,) is univalent, because three of the four valences of the carbon atom are satisfied by atoms of hydrogen, leaving one free valence. The radical (PO) of phosphoric acid is trivalent, because two of the five valences of the phosphorus atom are satisfied by the two valences of the bivalent oxygen atom, leaving three free valences. 

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