Preconcentration of some phosphorus-containing anions by adsorption on hydrated iron(III) oxide

The adsorption behaviour of orthophosphate, triphosphate, pyrophosphate, monomethylphosphate, phosphite, α- and β-glycerophosphates, dimethylphosphate, and hypophosphite on hydrated iron(III) oxide precipitate is studied as a function of pH. Orthophosphate is adsorbed quantitatively at pH 4.0–8.0, triphosphate and pyrophosphate at pH 4–9.3 and the next three compounds at pH 4–6.8. The last two ions were only slightly adsorbed at any pH examined.     

Oxidation of phosphorus centers by ferrate(VI): spectral observation of an intermediate

The kinetics and mechanism for the oxidation of phosphite, hypophosphite, phenylphosphite, and trimethylphosphite by ferrate(VI) are reported. Hypophosphite is rapidly oxidized to phosphite which is slowly oxidized to phosphate, trimethylphosphite is oxidized to trimethylphosphate, and phenylphosphite is oxidized phenylphosphate. (18)O induced shifts of the (31)P NMR signals support oxygen transfer from ferrate(VI) to the phosphorus center during the oxidation process. Deuteration of the hydridic hydrogens in hypophosphite and phosphite resulted in significant kinetic isotope effects on the reaction rates. It is proposed that ferrate(VI) acts as a two-electron oxidant in conjunction with oxide transfer coupled with phosphorus hydrogen bond breaking for phosphite and hypophosphite and simple oxygen transfer for trimethylphosphite and phenylphosphite.     

Determination of phosphite,hypophosphite, tellurium and mercury

A new catalytic oxidation procedure, involving the use of a cerium(IV) sulfate reagent in perchloric acid with a mixed silver(I)—manganese(II) perchlorate catalyst, has been developed for the determination of phosphite, hypophosphite, and tellurium. By this method 15—100 mg of phosphite, 5—35 mg of hypophosphite, and 10—105 mg of tellurium may be determined with standard deviations of ±0.17, ±0.32, and ±0.21% respectively. A direct titration procedure for mercury(I) is described using a ceric perchlorate solution as titrant with the mixed catalyst system. Samples from 65–510 mg may be analyzed with a standard deviation of ±0.36%.     

Mechanism and kinetics of hypophosphite oxidation by permanganate ion

The kinetics of the permanganate‐hypophosphite redox reaction has been studied over a wide range of pH by using a stopped‐flow technique. It has been found that the reaction leads to the formation of phosphite and orthophosphate, and that the molar ratio of the final products depends on pH. The proposed mechanism of the process was based on the assumption that the first step in the oxidation of hypophosphite is a fast reversible reaction in which an intermediate complex (O₃MnOH₂PO₂)²⁻ is formed. The observed dependence of the reaction rate on pH was attributed to the influence of hydrogen and hydroxyl ions on the decomposition of this complex. The rate constants and the equilibrium constants of elementary reactions are given. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 737–743, 1999     

Separation of oxyanions of phosphorus by single column ion chromatography

Separation of mixtures containing hypophosphite, phosphite, orthophosphate, chloride, nitrate and sulphate ions has been achieved using a Vydac 300 IC 405 column, refractive index detection and eluents which were 2mM in p-hydroxy benzoic acid or 4mM in p-amino benzoic acid (adjusted to ph 5.5). Calibration curves were linear over the concentration range 3 to 30 mg P/l.; and the precision (RSD for peak heights in mixtures) was < +/- 10%. Using p-hydroxy benzoic acid, detection of eluted peaks by indirect UV absorption was equally satisfactory. In an initial survey, the elution behaviour of nine oxyanions of phosphorus (simple ions and condensed species) was examined, using eluents containing different organic carboxylic acids (six aliphatic and nine aromatic), present at levels of 1 to 5m(M); with the pH adjusted to values between 3 and 8.6. No suitable conditions for separating mixtures containing condensed phosphates were identified.     

Studies in qualitative inorganic analysis. Part XLII

Summary Tests are given for the qualitative detection and confirmation of orthophosphate, pyrophosphate, phosphite, hypophosphite, hypophosphate, trimetaphosphate, tetrametaphosphate, tripolyphosphate, and high molecular weight phosphates.

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Zusammenfassung Reaktionen für den qualitativen Nachweis und die Unterscheidung folgender Anionen wurden angegeben: Ortho- und Pyrophosphat, Phosphit, Hypophosphit, Hypophosphat, Trimetaphosphat, Tetrametaphosphat, Tripolyphosphat und hochmolekulare Phosphate.

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Part XLI: Mikrochim. Acta [Wien]1970, 1287.     

Vibrational spectroscopic study of the hypophosphite and phosphite anions,H2PO2−2 and HPO2−3, and of their deuteriated analogues in the solid state and in aqueous solution

A full vibrational spectroscopic study of sodium hypophosphite, sodium phosphite and their deuteriated analogues has been made. The vibrations characteristic of the hypophosphite anion have been assigned and the presence of a previously unreported band has been established for the Raman spectrum of the aqueous solution. The first Raman study of deuteriated sodium phosphite has been undertaken and a full vibrational assignment is given.     

New approaches to the synthesis of aromatic polyesters

A new method of the synthesis of high molecular polybutylene terephthalate (PBT) is developed with the use of Irganox 1010, tris(nonylphenyl) phosphite and hypophosphite as stabilizers and boron nitride or boron oxide as a catalyst is proposed.     

Determination of hypophosphite and phosphite by their reduction of iodine,iodate, or periodate and mercury(I) titration of iodide

A new potentiometric method is adopted for the accurate determination of hypophosphite and phosphite alone or in their mixtures using alcoholic iodine, iodate, and periodate. Hg(I) was used as titrant for the produced iodide in case of using alcoholic iodine as oxidant or for the excess added iodide in case of iodate and periodate as oxidants using silver amalgam as the indicatior electrode. The potential breaks which average 300 mV per 0.1 ml of titrant were sharp enough for precise determination of endpoints, and hence the high accuracy of the present method.     

Oxidative Alkoxylation of Hypophosphite in Coordination Sphere of Iron(III)

The kinetics of oxidation of sodium hypophosphite with oxygen in Fe(III) alcoholic solutions is studied. At 50-90°C, hypophosphite was found to be oxidized to dialkyl phosphite (RO)₂HPO, di-, and trialkyl phosphates (RO)₂(OH)PO, (RO)₃PO. The redox potentiometry, IR, UV, EPR, Mössbauer, and ³¹P NMR spectroscopies, X-ray powder diffraction analysis, and gas-liquid chromatography were used to determine the key stages of the process: the Fe(III) reduction with hypophosphite with the formation of the phosphorus ethers and the reoxidation of Fe(II) with oxygen. The molar ratio of the products depends on the composition of the Fe(III) coordination sphere.     

Electrocatalytic Oxidation of Hypophosphite on Nickel Electrode ──In Situ UV-Vis Spectroscopic study

ThefactthathypophosphiteisoneofthemostwidelyusedreducingagentsintheNielectrolessdepositionhasstimulatedthestudyofanodicoxidationofhypophosphiteonnicked-ic.Thisanodicreaction,whichisimportantfortheunderstandingoftheNielectrolessdepositionmechanism,isexpectedtobeoneoftheimportantreactionsintheNi-electrolessprocess.Recently,theroleandoxidationmechanismofhypophosphiteinelectrolessdepositionofNi-Palloyhavebeenstudiedindetailusingtheprobebeamdeflection',electrochemistryandinsituIR',lo.However,som…     

A Simple Test to Confirm the Ligand Substitution Reactions of the Hydrolytic Iron(iii) Dimer

Using a novel test method based on initial rates, periodate, dithionate, selenite, phosphite, hypophosphite, and arsenate ions were confirmed to form transient multinuclear iron(III) complexes directly with the iron(III) hydroxo dimer Fe₂ (OH)₂ (H₂ O)8     

Elucidating the redox cycle of environmental phosphorus using ion chromatography

Historically, it was assumed that reactive, inorganic phosphorus present in pristine environments was solely in the form of orthophosphate. However, this assumption contradicts theories of biogenesis and the observed metabolic behavior of select microorganisms. This paper discusses the role of ion chromatography (IC) in elucidating the oxidation-reduction cycle of environmental phosphorus. These methods employ suppressed-IC, coupled with tandem conductivity and electrospray mass spectrometry detectors to identify and quantify phosphorus oxyanions in natural water, synthetic cosmochemical, and biological samples. These techniques have been used to detect phosphite and orthophosphate in geothermal hot springs. Hypophosphite, phosphite, and orthophosphate have been detected in synthetic schreibersite corrosion samples, and termite extract supernatant. Synthetic schreibersite corrosion samples were also analyzed for two poly-phosphorus compounds, hypophosphate and pyrophosphate, and results show these samples did not contain concentrations above the 1.3 and 2.0 μM respective 3σ limit of detection. These methods are readily adaptable to a variety of matrices, and contribute to the elucidation of the oxidation-reduction cycle of phosphorus oxyanions in the environment. In contrast to most studies, these techniques have been used to show that phosphorus actively participates in redox processes in both the biological and geological world.     

Anodic and cathodic process of hypophosphite on a Ni-Ag electrode

The reduction and the oxidation of hypophosphite on a Ni-Ag electrode have been studied to provide the information about the phosphorus incorporation mechanisms during the electro-less deposition and the electrodeposition of Ni-P alloys.In the electrooxidation process,an absorbency band around 240nm,which was ascribed to the formation of an intermediate PHO2-,was observed by in situ UV-Vis subtractive reflectance spectroscopy.Accordingly,the electrooxidation of hypophosphite might undergo an H abstraction of hypophosphite from the P-H bond to form the phosphorus-centred radical ' PHO2- ,which was subsequently electrooxidized to the final product,phosphite.In the reduction process Ni-phos-phine compound Ni-(PH3)n was observed by in situ surface Raman spectroscopy.The results from the Raman experiments show that,in the NiSO4-free solution,hypophosphite was reduced only to Ni-phosphine compound,while in the case where NiSO4 coexisted in the solutions,the Ni-phosphine compound,as an intermediate,was oxidise     

酸性溶液中NaH2PO2在铂电极上氧化的原位红外光谱研究

用SNIFTIRS和循环伏安法研究酸性溶液中次亚磷酸钠在多晶铂电极上的电氧化机理.分析了0.5mol/LH2SO4+0.1mol/LNaH2PO2溶液中原位红外反射谱图与电极电位的关系,发现在发生反应的电位下Pt电极上的吸附物种有氢原子和H2PO2,最终的氧化产物是H3PO4而不是H2PO3-,据此提出了酸性介质中次亚磷酸根离子在Pt上氧化的新机理.     

Synthesis of phosphorous acid and its derivatives based on the reaction of elemental phosphorus (P4) and aqueous solution of choline in the presence of the hydroxides of earth alkali metals

A nonchloric method for the synthesis of phosphorous acid and barium and calcium phosphites is proposed, involving the reaction of elemental phosphorus (P₄) with aqueous barium and calcium hydroxides in the presence of quaternary ammonium base (choline). Conditions for the preparation of high‐purity phosphorous acid based on the oxidation of the hypophosphite ion to the phosphite ion in a strong alkali medium were studied. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:517–519, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20472     

Stoichiometric measurements in nickel–hypophosphite baths for electroless deposition

Titrimetric methods and ³¹P NMR spectrometry have been compared for the determination of hypophosphite (H₂PO⁻₂) and phosphite (HPO^·-₃) in both alkaline and acid solutions used in the electroless deposition of nickel-phosphorus alloys. It has been shown that reproducible and reliable redox titrimetric methods can be used to follow the charges in concentration of both species with time during the plating process. In addition, measurements of the phosphorus in the nickel deposit by conversion to phosphate in acidic solution and use of flow-injection analysis has enabled satisfactory phosphorus mass-balance in the system to be achieved.     

Kinetics of the oxidation of hypophosphite,deuteriohypophosphite, phosphite and neutralized phenyl phosphonous acid by tris(pyridine-2-carboxylato)manganese(III) in picolinate-picolinic acid buffer medium

Hypophosphite, deuteriohypophosphite, phosphite and neutralized phenyl phosphonous acid are oxidized by tris(pyridine-2-carboxylato)manganese(III) in Na(pic)–picH [where Na(pic) = sodium salt of picolinic acid and picH = picolinic acid] buffer in the 4.63–5.45 pH range. All the reactions appear to follow the same mechanistic pathway in which the substrate initially forms a 1:1 intermediate complex with the oxidant. The complex then breaks down in the rate-determining step to give a free radical intermediate which subsequently reacts with another molecule of oxidant to give the products. A deuterium isotope effect of k _H/k _D = 4.26 at 313 K, was observed in the oxidation of hypophosphite indicating that proton removal from phosphorus takes place in the rate-determining step. A mechanism consistent with the experimental observations has been proposed.     

Electrooxidation of the hypophosphite ion on a palladium electrode

Anodic oxidation of sodium hypophosphite on smooth Pd and Pd/Pt electrodes and a Pd membrane is studied. Thei vs.E curves for the Pd electrode exhibit two anodic current peaks. One is caused by oxidation of H₂PO ₂ ^- , and the other, by simultaneous ionization of Pd and oxidation of H₂PO ₂ ^- . The hypophosphite ion adsorbed on the Pd surface hinders the formation of the passive film. This brings about a rapid dissolution of Pd in the oxygen region and its subsequent deposition with the formation of palladium black. The oxidation probably includes a slow heterogeneous chemical reaction, specifically, a cleavage of the P-H bond of the hypophosphite ion. The change in the reaction stoichiometry following an increase in solution pH and in anodic polarization is probably due to changing conditions of the H₂PO ₂ ^- adsorption and the number of adsorption sites occupied by H₂PO ₂ ^- on the surface. Following an increase in polarization, the phosphite ion may undergo oxidation to phosphate. Deceased.     

Imido Analogues of Group 15 Oxoanions

Reactions of binary group 15 halides with primary amines in the presence of base and subsequent by metallation with n-butyllithium produces imido anions of the group 15 elements. Applications of this methodology to a range of group 15 halides are described along with the syntheses and X-ray crystal structures of three complexes which are the imido analogues of the orthophosphate anion, the phosphite anion and the arsenate anion respectively.