Chemistry in fuming nitric acids—I. NMR spectroscopic study of PF5, HPO2F2 and P4O10 in the solvent system 44 wt.% N2O4 in 100% HNO3

³¹P and ¹⁹F NMR spectroscopy has been used to elucidate the nature of the interaction of PF₅, HPO₂F₂ and P₄O₁₀ with the solvent system 44 wt.% N₂O₄ in 100% HNO₃ (“High Density Acid”, HDA). PF₅ generates the species PF₆^?, HPO₂F₂ and HF (with some H₂PO₃F present as a minor product). HPO₂F₂ gives rise to H₂PO₃F and HF (with smaller amounts of PF₆ also present). The ³¹P NMR spectrum of P₄O₁₀ in HDA exhibits four resonances assigned to P(OH)₄⁺, H₄P₂O₇, (HPO₃)₄ and a mixture of cyclic and branched phosphoric acids, respectively.     

Phase formation in the ZrO(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript>-CsF-H<Subscript>2</Subscript>O system at low concentration of the phosphorus-containing component

The ZrO(NO₃)₂-H₃PO₄-CsF-H₂O system was studied at 20°C along the section at a molar ratio of PO₄³⁻/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO₂ concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated for the first time: crystalline fluorophosphates CsZrF₂PO₄ · H₂O, amorphous oxofluorophosphate Cs₂Zr₃O₂F₄(PO₄)₂ · 3H₂O, and amorphous oxofluorophosphate nitrate CsZr₃O_1.25F₄(PO₄)₂(NO₃)_0.5 · 4.5H₂O. The compound Cs₃Zr₃O_1.5F₆(PO₄)₂ · 3H₂O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following new compounds was established: Cs₂Zr₃O_1.5F₅(PO₄)₂ · 2H₂O, Cs₂Zr₃F₂(PO₄)₄ · 4.5H₂O, and Zr₃O₄(PO₄)_1.33 · 6H₂O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical, thermal, and IR spectroscopic analyses.     

Thermal stability and X-ray luminescence properties of cesium fluorophosphatohafnates

The thermal stability of cesium fluorophosphatohafnates (crystalline CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O, CsHfF₂PO₄ · 0.5H₂O, CsHf₂F₆PO₄ · 4H₂O and X-ray amorphous Cs₂Hf₃O_1.5F₅(PO₄)₂ · 5H₂O, Cs₅H₄Hf₃F₇(PO₄)_3.66(NO₃)₃ · 5H₂O) was determined. The weight ratios Cs⁺/Hf and PO ₄ ^3? /ZrHf in CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O were confirmed by identifying the calcination production CsHf₂(PO₄)₃ (～1000°C). A new crystalline compound CsHf₂F(HPO₄)(PO₄)₂ was found by thermogravimetric and X-ray powder diffraction analysis during heating. A new method for hydrothermal synthesis of CsHf₂(PO₄)₃, which was different from the already known one, was proposed. It was ascertained that CsHf₂(PO₄)₃ possesses a significant X-ray luminescence; whereas in fluorophosphatehafnates show low luminescence intensity.     

Die Kristallstrukturen von zwei mononuklearen Peroxotitan (IV)-dipicolinaten

The crystal structures of two mononuclear peroxotitanium(IV) chelates, the triclinic, deep red, pleochroitic diaquoperoxotitanium dipicolinate [TiO₂(C₇H₃O₄N) (H₂O)₂]2H₂O, and the monoclinic, orange difluoroperoxotitanium dipicolinate K₂[TiO₂(C₇H₃O₄N)F₂]2H₂O, have been determined from X-ray diffractometer data, and refined to R = 2.7% (3488 reflections) and R = 5.1% (2324 reflections) respectively. Analogous to a yellow-orange dinuclear peroxotitanium dipicolinate described earlier, the utanium atoms are coordinated approximately pentagonal bipyramidally, with the peroxo group and the chelate ligand occupying the equatorial sites and with H₂O or F- forming the apices. The O? O bond length in the peroxo group is the same in all structures, but there is a very slight variation of the Ti-peroxide distances apparently connected with the colours of the compounds. The more basic the apical ligands are (H₂O → F^? → μ-oxygen), the higher is the frequency of the absorption band, the longer are the Ti-peroxide distances, and the shorter are the apical bond lengths. Difference Fourier maps based on the final structures agree with this. The red diaquo complex shows highest residual peaks between titanium and the peroxo group, whereas the orange difluoro complex shows them near the apical Ti? F bonds. The packing of the complexes and hydrogen bonding are discussed. H? O distances seem to indicate that the very acidic diaquo complex is near a transitional state towards a hydroxonium salt.     

Phase formation in the ZrO(NO3)2-H3PO4-CsF(HF)-H2O system

The phase formation in the system ZrO(NO₃)₂-H₃PO₄-CsF(HF)-H₂O was studied at the molar ratio CsF/Zr = 1 along the sections PO ₄ ^3? /Zr = 0.5 and 1.5 at a ZrO₂ concentration in the initial solution of 2?C14 wt %. The following compounds were isolated: Cs₅Zr₄F₂₁ · 3H₂O, CsZr₂(PO₄)₃ · 2HF · 2H₂O, CsZrF₂PO₄ · H₂O, CsZr₂F₆PO₄ · 4H₂O (for the first time), CsHZrF₃PO₄ (for the first time), Cs_0.70ZrF(PO₄)_1.23 · nH₂O, and CsHZr₂F₂(P_O4)_2.66 · nH₂O. The compositions of CsZrF₂PO₄ · H₂O, Cs_0.70ZrF(PO₄)_1.23 · nH₂O, and CsHZr₂F₂(PO₄)_2.66 · nH₂O are conditional. All the compounds were characterized by crystal-optical, X-ray powder diffraction, thermal analyses, and IR spectroscopy. The formula CsHZrF₃PO₄ was established by energy-dispersive analysis with a LEO-1450 scanning electron microscope and an MS-46 CAMECA X-ray microanalyzer.     

Untersuchungen zur Darstellung des Phosphorsäurefluoridpyridiniumbetains,Py · PO2F (Py = Pyridin)

Studies on the Preparation of the Phosphoric Acid Fluoride Pyridinium Betaine, Py · PO₂F (Py = Pyridine) Under anhydrous reaction conditions phosphoric acid chloride betaine, Py · PO₂Cl ( I ), does not react with NaF or NaSO₂F to the corresponding fluorine compound Py · PO₂F ( II ). Reaction between AsF₃ and I gives rise to the formation of compound II which is detectable by N.M.R. In an excess of pyridine POCl₂F reacts with P₄O₁₀ to a mixture of I and II which are difficult to be separated. In a preparatively simple way II can be obtained by sulfur-oxygen exchange in liquid SO₂ starting from dithiophosphoric acid fluoride betaine Py · PS₂F.     

Preparation de nouveaux difluorodioxophosphates a partir de l’oxyde de difluorure de phosphoryle Partie V. Reactions aur le trioxyde d’uranium

UO₂(PO₂F₂)₂ has been synthesized from the action of P₂O₃F₄ on UO₃ or uranyl nitrate. The monofluorophosphate UO₂(PO₃F) was obtained by thermal decomposition. Infrared and Raman spectroscopic investigation of UO₂(PO₂F₂)₂ suggest a chain structure with oxygen phosphorus-oxygen bridges.     

Thermal stability and X-ray luminescent properties of cesium fluorophosphatozirconates

Crystalline cesium fluorophosphatozirconates (CFPZs) CsZr₂F₆PO₄ · 4H₂O, CsZrF₂PO₄ · 0.5H₂O, CsH₂Zr₂F₂(PO₄)₃ · 2H₂O, and amorphous Cs₂Zr₃OF₆(PO₄)₂ · 3H₂O were synthesized, and their thermal stability and luminescence ability were studied. The compositions of initial CsH₂Zr₂F₂(PO₄)₃ · 2H₂O and Cs₂Zr₃OF₆(PO₄)₂ · 3H₂O were refined. CsZr₂O_0.5F₅PO₄, CsHZr₂F(PO₄)₃, CsZr₂(PO₄)₃, and Cs₂Zr₃OF₆(PO₄)₂ crystalline intermediates, which are comparable with BaSO₄ and CaF₂ luminophors in the context of their X-ray luminescence intensity, were recognized by thermal analysis and X-ray powder diffraction under heating.     

Phase formation in the systems TiOCl2-H3PO4-MF(HF)-H2O (M = K, Rb, Cs)

From solutions containing 2–17 wt % TiO₂ at the molar ratios M/Ti = 1–4, F/Ti = 2–4, and PO ₄ ^3? /Ti = 0.5–10 under mild conditions, fluoro- and oxo(hydroxo) fluorophosphate titanates were isolated: crystalline M₂TiF₆ (M = K, Rb, Cs) and K₂Ti₂O_2.5F₂PO₄ · 2H₂O, and amorphous K₃Ti₄O(OH)F₇(PO₄)₃ · 5H₂O, Cs₂Ti₃O₂F₇PO₄ · 6H₂O, and CsTi₃O₃F₄PO₄ · 3H₂O. In a mixture with M₂TiF₆ and KCl, phosphate-ion-containing crystalline phases of unidentified composition were detected. The phases were studied by elemental, crystal-optical, X-ray powder diffraction, thermal, IR spectroscopic, and electron microscopic analyses. Annealing fluorophosphate titanates gives a mixture of MTiOPO₄ and TiO₂. All the mentioned alkali metal fluorophosphates contain the tetrahedral ion PO ₄ ^3? and titanium polyhedra with bonds Ti-F and Ti-O; some of them also contain bridging oxygen connecting titanium atoms: Ti-O-Ti; i.e., these substances are polymeric.     

Kristallographische Orientierungsbeziehungen zwischen den Phasen der Reaktionsfolge Ca2[P4O12] · 4 H2O → β-(Ca2[PO3]4)x

Crystallographic Orientation Relations between the Phases in the Reaction Ca₂[P₄O₁₂] · 4 H₂O → β-(Ca₂[PO₃]₄)_x The dehydration of Ca₂[P₄O₁₂] · 4 H₂O modification I proceeds over several intermediate phases to β-(Ca₂[PO₃]₄)_x crystallographically oriented. One of the intermediate phases is X-ray amorphous. It is of special interest, that this amorphous phase does not interrupt the oriented course of the reaction. The β-polyphosphate transforms to β-Ca₂[P₂O₇] connected with the loss of P₂O₅ at further heating. The crystallographic orientation relations between educt and product were determined for all steps of the reaction. The unit cells of the phases were determined too.     

Synthesis and Crystal Structure of meso-Δ,Λ-μ-Peroxo-μ-hydroxobis[bis(ethylenediamine)rhodium(III)]trifluoromethane Sulfonate

The reaction of the meso-diol, Δ,Λ-[(en)₂Rh(OH)₂Rh(en)₂]⁴⁺, with aqueous H₂O₂ and 1 equiv. of NaOH at 90° forms the μ-peroxo-μ-hydroxo-bridged species Δ,Λ-[(en)₂Rh(O₂,OH)Rh(en)₂]³⁺ in a yield of ca. 50%. The compound was crystallized as perchlorate and trifluoromethanesulfonate salts. The structure of the latter salt was determined by single-crystal X-ray diffraction. The crystals are triclinic with space group P1 and lattice constants a = 11.895(5), b = 12.491(4), c = 13.053(5) Å, α = 103.98(3), β = 92.59(3), γ = 119.52(6)°. The distances of the metal centres to the bridging peroxo ligand are 1.999(8) and 1.983(6) Å. The O? O distance in the peroxo group is 1.521(14) Å, and the dihedral angle of the Rh? O? O? Rh unit deviates 65° from planarity. The peroxo complex reacts reversibly with acid, and spectrophotometric studies suggest that the reaction involves protonation of the peroxo bridge, with pK_a = 2.70(2) at 25° in 1M NaClO₄.     

Synthesis of 6-amino-4-aryl-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles by heterogeneous reusable catalysts

A new, efficient and environmentally benign protocol for the one-pot, four-component synthesis of 1,4-dihydropyrano[2,3-c]pyrazoles by reaction of hydrazine monohydrate, ethyl acetoacetate, arylaldehydes and malononitrile in the presence of a green catalytic amount of P₂O₅/SiO₂, H₃PO₄/Al₂O₃, cellulose sulfuric acid and starch sulfuric acid is described. The use of non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are the advantages of this method.     

Sur L'Existence d'un Intermediaire Reactionnel Entre Phosphate et Pyrophosphate Acide de Potassium: Cas de K2H8(PO4)2P2O7

On the Existence of Intermediate Reaction Products of Potassium Hydrogen Phosphate and Diphosphate: K₂H₈(PO₄)₂P₂O₇ The crystal structure of K₂H₈(PO₄)₂P₂O₇ has been determined from diffractometer data obtained using MoKα radiation. The space group is Pca2₁ with a = 9.364(2), b = 7.458(2) and c = 19.560(2) Å, V = 1 366.0 ų; d_m = 2.17(1) g/cm³. Z = 4 · μ(MoKα) = 12.47 cm^?1. The structure was solved by direct methods. The crystal structure was refined to R = 0.025 for 416 independent reflexions. Two kinds of PO₄ exist and the mean value of P? O is 1.55(2) Å for one and 1.53(2) Å for the other. In P₂O₇ the angle P? O? P is 135(1)°. The distances P? O of bridge are 1.59(2) and 1.57(2) Å the mean value of P? O in terminals ? PO₃ is 1.51(2) Å. The coordination numbers of the potassium ions are nine and eight. K₂H₈(PO₄)₂P₂O₇, compound with mixed anion PO₄/P₂O₇ may be considered as reactional intermediary between acid orthophosphate and pyrophosphate.     

Reaction Mechanism in the Mixtures of Calcium Polyphosphate with Apatite and Accompanying Minerals on Heating

Abstract

On obtaining defluorinated feeding phosphates from Kovdor apatite the system of Ca₁₀(PO₄)₆(OH)_1,4F_0,6-CaCO₃-(Ca,Mg)CO₃-Mg₂SiO₄-Ca(H₂PO₄)₂·H₂O-Mg(H₂PO₄)₂·xH₂O with mole correlation (CaO+MgO)/P₂O₅V3 is subjected to thermal treatment. On heating up to 500°C calcium and magnesium hydrophosphates turn into polyphosphates M(PO₃)₂ which in accordance with the increase of the temperature react with other components of the system. To establish the mechanism and conditions for reactions, thermal interactions in the mixtures of Ca(PO₃₎₂ and Ca₂P₂O₇ with apatite, phorsterite, dolomite and calcite when (CaO+MgO)/P₂O₅=3 have been investigated. Methods of chemical, thermal, chromatographic, X-ray and IR-spectroscopy analysis were used.     

Etude des spectres vibrationnels et des proprietes physico-chimiques du cyclotriphosphate mixte de nickel et de sodium hexahydrate,NiNa4(P3O9)2.6H2O

A study of the vibrational spectra and physico-chemical properties of nickel and sodium cyclotriphosphate hexahydrate, NiNa₄(P₃O₉)₂.6H₂O. We have studied the dehydration and the calcination under atmospheric pressure of cyclotriphosphate hexahydrate of nickel and sodium, NiNa₄(P₃O₉)₂.6H₂O, between 25 and 700°C by infrared spectrometry, X-ray diffraction, TGA and DTA thermal analyses. This study allows the identification and the crystallographic characterization of a new phase, NiNa₄(PO₃)₆, obtained between 350 and 450°C. NiNa₄(PO₃)₆ crystallizes in the triclinic system, P₋₁, with the following unit cell parameters a = 6.157(3)Å, b = 6.820(6)Å, c = 10.918(6)Å, α = 80.21(5)°, β= 97.80(9)°, γ = 113.49(3)°, V = 409.8 ų, Z = 1, M(19) = 25 and F(19) = 48 (0.0095; 42). The calcination of NiNa₄(PO₃)₆, between 500 and 600°C, leads to a mixture of long-chain polyphosphates NiNa(PO₃)₃ and NaPO₃. The kinetic characteristics of the dehydration of NiNa₄(P₃O₉)₂.6H₂O were determined and discussed. The vibrational spectrum of the title compound, NiNa₄(P₃O₉)₂.6H₂O, was interpreted in the domain of the stretching vibrations of the P₃O₉ rings, on the basis of its crystalline structure and in the light of the calculation of the normal IR frequencies of the P₃O₉ ring with D_3h symmetry.     

Kinetics of the Kola Apatite Rock Interaction With H3PO4

Abstract

Besides the production of fertilizers, Kola phosphate rock may be used as a source of lanthanides, strontium and fluorine. It implies the necessity to carry out a study of kinetics and mechanisms of the process in order to choose optimal conditions for the realization of the technological scheme [1]. The fluorapatite concentrate used had the following composition: ?Ln₂O₃ - 0.89; Y₂O₃ - 0.04; SrO - 2 80; CaO - 45.40; Fe₂O₃ -0.42; Al₂O₃ - 0.86; MgO - 0 10; F - 2.80; SiO₂ - 1.80; P₂ ^O ₅ - 39.40 weight %; molar ratio CaO : P₂O₅ = 1.5; the content of the apatite - 98.5%. The reaction of H₃PO₄ with fluorapatite was studied using a laboratory reactor with a stationary layer. The following parameters were varied: H₃PO₄ concentration (20, 30 and 50 weight % P₂O₅), temperature (20, 75, 150, 200 and 250°C) and time of contact (1–180 min.). A multimethod approach was used. X-ray diffraction, electron probe microanalysis and paper chromatography were applied to follow the bulk structural aspects of the apatite powders. It was shown that at the first stage of reaction a thin film of calcium monophosphate Ca(H₂PO₄)₂ H₂O is deposited on the apatite particles (avg. diameter 150 nm). The reaction is thought to proceed at the interphase solid/liquid and its kinetics may be described by the equation     

Computational chemistry and molecular simulations of phosphoric acid

Quantum mechanics (QM) calculations, molecular dynamics (MD) simulations using the condensed‐phase optimized molecular potentials for atomistic simulation studies (COMPASS) force field, and the atom‐centered density matrix propagation (ADMP) approach have been used to investigate properties of phosphoric acid (PA). QM using B3LYP/6‐31++G(d,p) density functional theory were used to calculate gas‐phase proton affinities and interaction energies of PA and its derivatives. Detailed single coordinate driving, followed by quadratic synchronous transit optimization was used to determine energy barriers for different proton transfer (PT) pathways. Determined energy barrier heights in ascending order are (unit: kJ/mol): H₃O⁺→H₃PO₄ (0); H₄P₂O₇→H₃PO₄ (2.61); H₃PO₄→H₂PO (5.31); H₄PO→H₃PO₄ (～7.33); H₃PO₄→H₄P₂O₇/H₃PO₄→H₃PO₄ (15.99); H₄P₂O₇→H₂O (28.61); H₃PO₄→H₂O (47.14). The COMPASS force field was used to study condensed‐phase properties of PA. Good agreement between experimental data and MD results including density, radial distribution functions, and self‐diffusion coefficient at different temperatures provides validation of the COMPASS force field for PA. Finally, preliminary ADMP studies on a cluster of three PA molecules shows that the ADMP approach can reasonably describe the PT and self‐dissociation processes in PA. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Correlation of the extraction constants of the system Cd(II)–H3PO4/Cyanex 302–kerosene at different ionic strengths

Bromley's theory for calculating activity coefficients in order to correlate the values of cadmium extraction constant by Cyanex 302 from phosphoric acid solutions at different ionic strengths has been applied. A chemical model for the aqueous phase including the species H₃PO₄, H₂PO₄⁻, H₅P₂O₈⁻, H₆P₂O₈, CdHPO₄ and CdH₂PO₄⁺ has been considered. The increase observed for the extraction constant value when increasing the phosphoric acid concentration is probably due to the significant increase of the cadmium activity coefficient. A reaction extraction including water as a component has been proposed, and the value of the thermodynamic extraction constant of log K⁰=7.02 for the formation of CdR₂(HR) species, HR being the major component of Cyanex 302, has been obtained.     

Preparation,Single Crystal Structure Analysis,and Thermal Behaviour of the Acidic Mercury(I) Phosphate (Hg2)2(H2PO4)(PO4)

Yellowish single crystals of acidic mercury(I) phosphate (Hg₂)₂(H₂PO₄)(PO₄) were obtained at 200 °C under hydrothermal conditions in 32% HF from a starting complex of microcrystalline (Hg₂)₂P₂O₇. Refinement of single crystal data converged at a conventional residual R[F² > 2σ(F²)] = 3.8% (C2/c, Z = 8, a = 9.597(2) Å, b = 12.673(2) Å, c = 7.976(1) Å, β = 110.91(1)°, V = 906.2(2) ų, 1426 independent reflections > 2σ out of 4147 reflections, 66 variables). The crystal structure consists of Hg₂²⁺‐dumbbells and discrete phosphate groups H₂PO₄^– and PO₄^3–. The Hg₂²⁺ pairs are built of two crystallographically independent Hg atoms with a distance d(Hg1–Hg2) = 2.5240(6) Å. The oxygen coordination sphere around the mercury atoms is asymmetric with three O atoms for Hg1 and four O atoms for Hg2. The oxygen atoms belong to the different PO₄ tetrahedra, which in case of H₂PO₄‐groups are connected by hydrogen bonding. Upon heating over 230 °C, (Hg₂)₂(H₂PO₄)(PO₄) condenses to (Hg₂)₂P₂O₇, which in turn disproportionates at higher temperatures into Hg₂P₂O₇ and elemental mercury.     

Salze von Halogenophosphorsäuren. XIX. Über die Darstellung von Kupfer(II)-monofluorophosphat-Solvaten und die Kristallstruktur von Aquamonofluorophosphatokupfer(II)-1,4-Dioxan 2/1, 2[Cu(H2O)PO3F] · C4H8O2

Salts of Halogenophosphoric Acids. XIX. Preparation of Copper(II) Monofluorophosphate Solvates and the Crystal Structure of Aquamonofluorophosphatocopper(II)-1,4-Dioxane 2/1, 2[Cu(H₂O)PO₃F] · C₄H₈O₂ The mixed solvate Aquamonofluorophosphatocopper(II)-1,4-Dioxane 2/1 1 was obtained by the reaction of aqueous solutions of NH₄HPO₃F and acidified (NH₄)₂PO₃F, respectively, using 1,4-dioxane as precipitating agent. 1 crystallizes in the monoclinic space group C2/m with a = 2130.9(2), b = 655.45(6), c = 447.30(4) pm, b? = 96.207(7)° and Z = 2. Copper(II) monofluorophosphate-methanol 1/1, CuPO₃F · CH₃OH 2 was obtained by the reaction of copper(II) salts with alkaline or ammoniummonofluorophosphates in methanol. 1 and 2 react in the presence of water vapor to copper(II) monofluoro phosphate dihydrate, CuPO₃F · 2H₂O 3 , which reacts reversibly with dioxan or CH₃OH under formation of 1 and 2 , respectively.