Tertiary metal phosphates

The tertiary metal phosphates are of the general formula MPO where M is B, Al, Ga, Fe, Mn, etc. The metal—oxygen bonds of these materials have considerable covalent character. The anhydrous salts are continuous three-dimensional networks analogous to the various polymorphic forms of siHca. Of limited commercial interest are the alurninum, boron, and iron phosphates. Boron phosphate [13308-51 -5] BPO, is produced by heating the reaction product of boric acid and phosphoric acid or by a dding H BO to H PO at room temperature, foUowed by crystallization from a solution containing >48% P205- Boron phosphate has limited use as a catalyst support, in ceramics, and in refractories. 

Tertiary amine polymethacrylates, 20 471 tertiary-butyldimethylsilyl (TBDMS), cleavage of, 16 559, 560 Tertiary creep, 13 472 Tertiary diperoxyketals, 18 457 Tertiary metal phosphates, 18 840 Tertiary nitriles, 12 180 Tertiary phosphine oxides, 19 66 Tertiary phosphines, 19 64 Tertiary recycling, 21 449 of PET, 21 450... 

A typical suite of X-ray diffractograms is shown in Fig. 8 for bottom ash samples. Diffraction peaks differ between sample treatments. With bottom ash, a large amorphous background signal is present. Thirty to 40 peaks are selected for analysis in the search match software. As shown in Tables 6 to 8, a number of metal phosphates were found in the treated samples and the treated and leached samples for the bottom ash, scrubber residue, and vitrification dust samples. Apatite family and tertiary metal phosphates are common to both the treated and unleached samples and the treated and leached samples for all three ashes. 

Hydrogenis prevented from forming a passivating layer on the surface by an oxidant additive which also oxidizes ferrous iron to ferric iron. Ferric phosphate then precipitates as sludge away from the metal surface. Depending on bath parameters, tertiary iron phosphate may also deposit and ferrous iron can be incorporated into the crystal lattice. When other metals are included in the bath, these are also incorporated at distinct levels to generate species that can be written as Zn2Me(P0 2> where Me can represent Ni, Mn, Ca, Mg, or Fe. 

Metal oxide sensors (MOS), smart, 22 717 Metal oxide supported catalysts, 5 336-337 coke formation on, 5 267—270 Metal passivation, in industrial water treatment, 26 137 Metal peroxides, 18 410 Metal phosphates, tertiary, 18 840 Metal-phosphorus alloys, 19 59 Metal phthalocyanines, electrochromic materials, 6 572t, 576-577 Metal prefinishing, detersive systems for, 8 413t... 

In zinc phosphating. a small amount of iron phosphate is formed initially, bul ihe bath contains primary zinc phosphate. ZnlHiP04)>, which crystallizes on Ihe metal surface as secondary and tertiary zinc phosphates, ZnHP04 and Znt(P04 j. respectively, when the pH rises at the mclal/solulion interlace. The most frequently used baths contain accelerators, preferably nitrates and nitrites, which oxidize the hydrogen lormcd hy the pickling reactions. The fundamental zinc phosphate reactions occur in three steps, all in the same hath ... 

In ihe coaling reaction, each 3 moles of iron or zinc liberates 4 moles of hydrogen ion. However, in the pickling reaction, 8 moles of hydrogen ion arc consumed. Thus, the pH at the metal interface rises, and insoluble tertiary ferrous phosphate and zinc phosphate crystallize on the iron surface. The coaling closest to the meta interface is largely iron phosphate, while that farther away is rich in zinc phosphate. 

The addition takes place according to Markownikoff s rule. The addition of carbo lic acida to the double bonds of isobutylene and trimethyl-ethylene gives tertiary esters. A true equilibrium independent of sulfuric acid concentrations is established in the exothermic reaction. The addition does not go well with ethylene, but goes well with many of the higher alkenes, particularly with some of the terpenes. To avoid the polymerizing effects of sulfuric acid, various other catalysts, such as sulfonic acids, triethylamine, hydrofluoric acid, boron trifluoride, and cuprous chloride have been used. The addition may take place at room temperature or higher and is aided by pressure. The vapors of the acid and hydrocarbon may be passed over catalysts, such as activated carbon, heteropoly acids, or metal phosphates. ... 

The neutralisation of free phosphoric acid by reaction 15.1 alters the position of equilibrium of equations 15.2, 15.3 and 15.4 towards the right and thereby leads to the deposition of the sparingly soluble secondary phosphates and insoluble tertiary phosphates on the metal surface. 

The relation between free phosphoric acid content and total phosphate content in a processing bath, whether based on iron, manganese or zinc, is very important this relation is generally referred to as the acid ratio. An excess of free acid will retard the dissociation of the primary and secondary phosphates and hinder the deposition of the tertiary phosphate coating sometimes excessive loss of metal takes place and the coating is loose and powdery. When the free acid content is too low, dissociation of phosphates (equations 15.2, 15.3 and 15.4) takes place in the solution as well as at the metal/solution interface and leads to precipitation of insoluble phosphates as sludge. The free acid content is usually determined by titrating with sodium... 

Solubility The phosphates of the alkali metals, with the exception of lithium, and of ammonium are soluble in water the primary phosphates of the alkaline earth metals are also soluble. All the phosphates of the other metals, and also the secondary and tertiary phosphates of the alkaline earth metals are sparingly soluble or insoluble in water. 

An interaction of metal ions with phosphates usually leads to stabilization of polynucleotide secondary and tertiary stmctures, depending on the metal ions and their concentrations, whereas base binding or chelating base and phosphate by the same metal ion may result in destabilization, conformational change, or denaturation of the polynucleotide structures (see also Sections 3.3.1 and 3.3.2). However, phosphate-specific binding can also induce significant conformational changes in DNA structure. The mechanisms of the latter structural interconversions are... 

The bulk of oxidations with tert-butyl hydroperoxide consists of epoxidations of alkenes in the presence of transition metals [147, 215, 216, 217, 218]. In this way, a,p-unsaturated aldehydes [219] and ketones [220] are selectively oxidized to epoxides without the involvement of the carbonyl function. Other applications of tert-butyl hydroperoxide such as the oxidation of lactams to imides [225], of tertiary amines to amine oxides [226, 227], of phosphites to phosphates [228], and of sulfides to sulfoxides [224] are rare. In the presence of a chiral compound, enantioselective epoxidations of alcohols are successfully accomplished with moderate to high enantiomeric excesses [221, 222, 223]. 

Furans and thiophenes normally undergo a-lithiation, but when substituted at the 2-position by an activating group, a competition arises between metalation at the 3-position (ortho lithiation) and the S-posi-tion (a-lithiation). 2-Oxazolinylthiophenes may be lithiated selectively at either the 3- or 5-position by adjusting the reaction conditions tertiary amides give little or no ortho selectivity, but secondary amides direct ortho lithiation reasonably well, as seen in Scheme 23. Both thiophenes and furans that are substituted with an oxazoline or tertiary amide at the 2-position may be dilithiated at the 3- and S-po-sitions. 76 Although secondary amides are less successful at directing ortho lithiation of furans than thiophenes, A, Af,M,lV -tetramethyldiamido phosphates work quite well. Subsequent hydrolysis affords access to butenolides. A typical example is shown in Scheme 24. 

Thorium is one of the few multivalent metals [others are Au(III), Ce(IV), U(VI), and Cr(VI)] which are extractable as nitrate complexes from nitric acid solutions [25-28]. The extractants used include TBP in CCI4 [26,29], TOPO in cyclohexane, toluene or xylene [25,30,31], and triphenylarsine oxide in CHCI3 [27]. Other reagents used for extraction of the nitrate complex of thorium include dibutyl dithiophosphate in various organic solvents [32], dibutyl sulphoxide in xylene [28], and bis(2-butoxyethyl) ether [33].The liquid anion-exchanger Aliquat 336 in xylene [34] and a solution of tertiary ammonium salt (Hyamine) in dichloroethane [35] have been also proposed for extraction of Th. The presence of Li, Na, or A1 nitrate improves the extraction of thorium. Sulphate, phosphate, and tartrate do not interfere, but fluoride must be masked, e.g., by aluminium. Thorium has been separated from U and Pu with the use of Alamine 336 and TOPO (in xylene or cyclohexane) [36]. 

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