Über Austauschversuche in Wasser und Deuteriumoxyd

Erlenmeyer, H.; Schoenauer, W.; Schwarzenbach, G.

doi:10.1002/hlca.193702001105

Cited by 14 publications

(4 citation statements)

References 18 publications

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“…At room temperature and neutral pH, the rate of isotope exchange between H2PO2 -1 (D2PO2 -1) or HPO3 -~ (DPO3 -2) and D20(H20) is negligible (8)(9)(10)(11)(12), but at room temperature and pH ~ 2 the rate of exchange for I'-I2PO2 -1 is comparable to the rate of decomposition cor~ducted at 100 ~ and neutral pH (13,14).…”

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confidence: 86%

“…Similarities between the behavior of the standard hydrogen electrode 'and that of Ni electrodes immersed in hot H2PO2 -1 solutions suggested that Ni electrodes are saturated with hydrogen (7). At room temperature and neutral pH, the rate of isotope exchange between H2PO2 -1 (D2PO2 -1) or HPO3 -~ (DPO3 -2) and D20(H20) is negligible (8)(9)(10)(11)(12), but at room temperature and pH ~ 2 the rate of exchange for I'-I2PO2 -1 is comparable to the rate of decomposition cor~ducted at 100 ~ and neutral pH (13,14).…”

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confidence: 98%

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The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

Marshall¹

1983

J. Electrochem. Soc.

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Hot aqueous hypophosphite (H2PO~ ') solutions are exhaustively decomposed to orthophosphite (HPO~2) in the presence of etched Ni wire according to the rate law d[H2PO~']/dt = -ko [H~PO~ ~] x (catalyst area). The activation energy is about 2.6 kcal/mol and the rate increases 4-fold with pH in the range 3 -< pH -< 7. Ni catalyzes the isotopic exchange between H~PO~ -~ and D20 as well as the decomposition. When [HPO~ -2] -> 0.15~/at the start of reaction, the catalyst is completely passivated with respect to the decomposition but not with respect to the isotopic exchange. The H2:HD:D2 volume ratio of the evolved gas is about 5:6:7. A mechanism for the decomposition is discussed and related to "electroless" plating.In spite of numerous investigations into the chemistry of "electroless" plating (1), experimental results relevant to the primal catalyzed hypophosphite decomposition Ni H2PO~ -1 + H20--> HPO3 -'2 ~ H2~ + H +1[1] A are few. Although H2PO~. -1 is distinguished by a standard redox potential of --0.SOV (2), reactions with most oxidizing agents are very slow, especially at 25 ~ and neural pH. This lack of reactivity is generally ascribed to very small concentrations of a "3-centered" intermediate (3-5) which H2PO2 -1 must rearrange prior to its oxidation.The electrochemical oxidation of H2PO2 -1 is also slow and occurs at appreciable rates only at elevated temperature on Ni and Pd surfaces (6). At room temperature only 02 is-evolved from an Ni anode, and H2PO2 -1 is not electrochemically oxidized on Pt even at elevated temperature.Similarities between the behavior of the standard hydrogen electrode 'and that of Ni electrodes immersed in hot H2PO2 -1 solutions suggested that Ni electrodes are saturated with hydrogen (7). At room temperature and neutral pH, the rate of isotope exchange between H2PO2 -1 (D2PO2 -1) or HPO3 -~ (DPO3 -2) and D20(H20) is negligible (8-12), but at room temperature and pH ~ 2 the rate of exchange for I'-I2PO2 -1 is comparable to the rate of decomposition cor~ducted at 100 ~ and neutral pH (13,14).Reaction [1] is negligible in the absence of catalyst at 100 ~ and does not take place without H20 (15). The .decomposition rate at 100 ~ is 1.2 mM/hr 9 cm 2 for [H2PO2-1] --0.25M (Fig. 2). In the presence of 3 mM Ni +2, but under otherwise comparable conditions, H2PO2 -1 is consumed at 3.2 mM/hr 9 cm 2 (16). During "electroless" plating ([Ni +2] -= 0.1M) H2PO2 -1 is consumed at 5 mM/hr 9 cm 2 (15).When H2PO2 -1 and D20 or D2PO2 -1 and H20 are decomposed at pH's between 3 and 5 over finely divided Ni, approximately equal amounts of the hydrogen isotopes are present in the evolved gas (17)(18)(19). During Ni plating the gas is heavily enriched in the hypophosphite isotope while this isotope is not detected in the water (17,20,21).Difficulties in preparing a reproducible Ni surface exhibiting a sustainable and useful level of activity have been a major hindrance to obtaining definitive mechanistic data. This problem was noted in Ref. (16 and 22). Catalyst sensitivity may be more noticeable under...

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confidence: 86%

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The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

Marshall¹

1983

J. Electrochem. Soc.

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“…For neutron diffraction a deuterated sample (sample 6) was prepared following the hypophosphorous route. Deuterated hypophosphorous acid easily can be prepared by proton‐deuterium‐exchange in D 2 O 15. The degree of deuteration was monitored by 31 P‐NMR spectroscopy.…”

Section: Powder Neutron Diffraction (Pnd)mentioning

confidence: 99%

Reinvestigation of Crystal Structure and Non‐Stoichiometry in Copper Hydride, CuH_1–x (0 ≤ x ≤ 0.26)

Auer

Kohlmann

2014

Zeitschrift anorg allge chemie

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Copper hydride and deuteride were reinvestigated by X-ray and neutron powder diffraction, revealing a pronounced phase width with respect to the hydrogen (deuterium) content. Synthesis from aqueous copper(II) sulfate with hypophosphoric acid solutions yields samples with a broad distribution of compositions and variations of up to 6.5 % in unit cell volume. The result is a metrical distortion with (hkl) dependent asymmetry and broadening of powder diffraction reflections. Patterns of such samples were described using a model with five copper hydride (deuteride) phases with different lattice parameters. A method for developing and refining reasonable multiphase models despite high correlation of parameters is described. Simulta-* Prof. Dr. H. Kohlmann

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“…Hence they suggested that the exchange and oxidation reactions take place by similar mechanisms and also that these mechanisms involve two tautomeric forms of hypophosphorous acid in aqueous solution. Further, the non-exchangeability of hypophosphite hydrogens in neutral solutions was established by Erlenmeyer et al (15) and verified by Jenkins and Yost (14). The existence of a tautomeric equilibrium was confirmed (14) and the exchange reaction is represented as:…”

Section: Resultsmentioning

confidence: 87%

Thallimetric oxidations Part VII: Titrimetric and spectrophotometric methods for the determination of hypophosphite and ternary mixtures of hypophosphite, phosphite, and oxalate

Rao¹,

Rao²,

Ramana³

et al. 1993

Can. J. Chem.

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. Can. J. Chem. 71, 80 1 (1993). Titrimetric and spectrophotometric methods are developed for the estimation of hypophosphite (PO:-) at mmol and micromol ranges, respectively. In these methods thallium(II1) is used as an oxidant and the reduced thallium(1) is determined either oxidimetrically by potassium bromate in the titrimetric method or by measurement of the optical density of thallium(II1) at 260 nm in the presence of 0.1 M NaCl and 1 M HC10, in the spectrophotometric method. Convenient methods are described for the determination of ternary mixtures of hypophosphite (poZ3-), phosphite PO^^-), and ox-A method is also described for the estimation of thallium(II1) using hypophosphite as reductant, and the method is applied to the determination of mixtures of thallium (1) (1) produit soit d'une f a~o n oxydimktrique, par le bromate de potassium dans la mkthode titrimktrique, soit par la mesure de la densitk optique du thallium(III), i 260 nm, en presence de NaCl 0,l M et de HCIO, 1 M, dans la mkthode spectrophotomktrique. On dkcrit des mkthodes faciles pour la determination d'ions hypophosphite (PO:-), phosphite (PO:-) et oxalate (c~o:-) dans des mClanges tertiaires. On dkcrit aussi une mkthode de dktermination de la concentration du thallium(II1) qui fait appel B I'hypophosphite comme rkducteur; on a appliquk la mkthode a des melanges de thallium(1) et de thallium(II1).[Traduit par la rkdaction]

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Über Austauschversuche in Wasser und Deuteriumoxyd

Cited by 14 publications

References 18 publications

The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

Reinvestigation of Crystal Structure and Non‐Stoichiometry in Copper Hydride, CuH_1–x (0 ≤ x ≤ 0.26)

Thallimetric oxidations Part VII: Titrimetric and spectrophotometric methods for the determination of hypophosphite and ternary mixtures of hypophosphite, phosphite, and oxalate

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Über Austauschversuche in Wasser und Deuteriumoxyd

Cited by 14 publications

References 18 publications

The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

The Nickel Metal Catalyzed Decomposition of Aqueous Hypophosphite Solutions

Reinvestigation of Crystal Structure and Non‐Stoichiometry in Copper Hydride, CuH1–x (0 ≤ x ≤ 0.26)

Thallimetric oxidations Part VII: Titrimetric and spectrophotometric methods for the determination of hypophosphite and ternary mixtures of hypophosphite, phosphite, and oxalate

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Reinvestigation of Crystal Structure and Non‐Stoichiometry in Copper Hydride, CuH_1–x (0 ≤ x ≤ 0.26)