Pressure and temperature effects on the excess deuteron and proton conductance

The limiting molar conductances ° of deuterium chloride DCl in D₂O were determined as a function of pressure and temperature in order to examine the proton-jump mechanism in detail. The excess deuteron conductances °_E(D ⁺), as estimated by the equation [°_E(D ⁺) = °(DCl/D ₂ O) – °(KCl/D ₂ O)], increases with an increase in the pressure and temperature as well as the excess proton conductance [°_E(H ⁺) = °(HCl/H ₂ O) – °(KCl/H ₂ O)]. The isotope effect on the excess conductances, however, depends on the pressure and temperature contrary to the model proposed by Conway et al.: °_E(H ⁺)/°_E(D ⁺) decreases with increasing pressure and temperature. The magnitude of the decrease with pressure becomes more prominent at lower temperature. These results are discussed in terms of the pre-rotation of adjacent water molecules, the bending of hydrogen bonds with pressure, and the difference in strength of hydrogen bonds between D₂O and H₂O.     

Fluordiazadiphosphetidine, 23. Mitt.: Die Herstellung neuer unsymmetrisch substituierter Fluordiazadiphosphetidine

Summary Using 1-chloromethyl-2,2,2,4,4,4-hexafluoro-3-methyl-1,3,2⁵,4⁵-diazadiphosphetidine as starting material for nucleophilic reactions, the following new compounds were prepared: 2,2,2,4,4-pentafluoro-4-methoxy-1-propyl-3-methyl-1,3,2⁵,4⁵-diazadiphosphetidine, 1-benzyl-2,2,2,4,4-pentafluoro-4-methoxy-3-methyl-1,3,2⁵,4⁵-diazadiphosphetidine, and 1-benzyl-2,2,2,4,4-pentafluoro-4-methylamino-3-methyl-1,3,2⁵,4⁵-diazadiphosphetidine

     

Unicyclic Graphs with Minimal Energy

If G is a graph and ₁,₂,..., _n are its eigenvalues, then the energy of G is defined as E(G)=|₁|+|₂|++| _n |. Let S _n ³ be the graph obtained from the star graph with n vertices by adding an edge. In this paper we prove that S _n ³ is the unique minimal energy graph among all unicyclic graphs with n vertices (n6).     

Simultaneous determination of yohimbine and boldine by first-derivative synchronous spectrofluorimetry

A method for the simultaneous determination of yohimbine and boldine in mixtures by first-derivative synchronous spectrofluorimetry has been developed. The method is based on their native fluorescence in 0.1N sulphuric acid medium. The constant wavelength difference chosen to optimize the determination was =_em -_em=82 nm. Yohimbine was measured at _ex//_em= 285/367 nm, and boldine at _ex/_em=272/354 nm. The range of application is 10–500 g/l for yohimbine and 1–50 g/l for boldine. The method was applied to the determination of yohimbine and boldine in synthetic mixtures and pharmaceuticals, with errors generally 2%. Relative standard deviations were about 2%.Dedicated to Professor Fermin Capitán on his 72th birthday     

Substituent dependence of the d-d transition band in the electronic absorption spectra of arylferrocenes and the corresponding arylferricenium salts

The electronic absorption spectra of 22 arylferrocenes and their arylferricenium salts with pentacyanopropenide (PCNP) were recorded. The attemptedHammett correlation of _max of the d-d transition bands of arylferrocenes revealed that this band is substituent dependent only for strong electron-withdrawing substituents. Excellent correlation of _max of the d-d transition bands with ⁺ constants was found in the case of arylferricenium cations. Good correlations of _max was also found with theE _1/2 oxidation potentials measured by cyclic voltametry.

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Substituentenabhängigkeit des d-d-Überganges in den Elektronenabsorptions-Spektren von Arylferrocenen und entsprechenden Arylferricenium-Salzen

Zusammenfassung Elektronenabsorptions-Spektren von 22 Arylferrocenen und ihren Arylferricenium-Pentacyanopropenid-Salzen wurden gemessen. VersuchteHammett-Korrelationen des längstwelligen d-d-Überganges (_max) zeigten, daß diese Bande nur von stark elektronenanziehende Substituenten abhängig ist. Im Fall der Arylferricenium-Kationen wurde eine ausgezeichnete Korrelation zwischen _max der d-d-Bande und den ⁺-Konstanten festgestellt. Eine gute Korrelation der _max-Werte wurde auch mit denE _1/2 Oxidationspotentialen gefunden, die durch cyclische Voltametrie meßbar sind.

     

Photoinduced Acylotropic Rearrangement of Crown-Containing 2-[N-Acetyl-N-(4-aminobenzo-15-crown-5)methylene]-2,3-dihydrobenzo[b]thiophen-3-one

2-N-(4-Aminobenzo-15-crown-5)methylene-2,3-dihydrobenzo[b]thiophen-3-one and its acetyl derivative were synthesized. Their treatment with lithium, sodium, or potassium iodide in acetonitrile solution leads to formation of the corresponding crown-metal complexes. Irradiation of the acylated compounds at 436 nm induces NO migration of the acetyl group to give O-acyl isomer which is characterized by a considerable blue shift of the long-wave absorption band ( = 70 nm). The quantum yields of the photo- induced acylotropic reaction for the free ligand and its complexes with alkali metal cations change in the series: _L > K⁺ > Na⁺ > Li⁺.     

Approximate theories of gelation

Summary The assumptions involved in approximate theories of gelation forRA ₂ +RB _f type random polymerisations are examined in detail. When the assumptionc _int c _ext is removed it is apparent that, contrary to previous findings, theFrisch theory is unable to explain existing gel-point data. A detailed development ofKilb's model for gelation is given and the expression _c (f – 1)(1 – _ab )² = 1 is derived as the condition for gelation. _c is the product of extents of reaction ofA andB groups at the gel point,f is the branchunit functionality, and _ab is a ring-forming parameter. _ab depends on the dilution of a reaction system, the molecular weights of the reactants and chain structures. It is shown how the derived expression can be used for reasonable predictions of _c for a given polymerisation system.

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Zusammenfassung Die Annahmen, worauf die simplifizierten Gelbildungstheorien betreffs einer Zufallspolymerisation desRA ₂ +RB _f Typs basieren, werden im einzelnen untersucht. Legt man die Annahmec _int c _ext ab, stellt sich heraus, daß dieFrisch-Theorie, im Gegensatz zu früheren Resultaten, die bekannten Gelpunktdaten nicht erklären kann. Eine Weiterentwicklung des Kilbschen Modelles wird vorgeschlagen und der Ausdruck _c (f - 1)(1 - _ab ² = 1 wird als Gelbindungsbedingung abgeleitet. _c ist das Produkt der Reaktionsumsätze derA- undB-Gruppen beim Gelpunkt;f = Funktionalität einer Verzweigungseinheit und _ab ist ein Ringbildungsparameter. _ab hängt von der Verdünnung eines Reaktionssystems, von den Molekulargewichten der reagierenden Moleküle und von ihren Kettenstrukturen ab. Es wird gezeigt, wie der so abgeleitete Ausdruck angewandt werden kann, um Werte für _c bei einer gegebenen Polymerisation vernünftig vorauszusagen.

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Dedicated to Herrn Prof. Dr. G. Rehage on the occasion of his 60th birthday.

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With 9 figures and 1 table     

Conductance of iron(III) laurate solutions in binary liquid mixtures

Summary The specific conductivity of iron(III) laurate solutions in binary liquid mixtures shows that the soap aggregates into micelles and CMC is found to be independent of temperature and concentration of benzene, acetone and tetrachloromethane in 1-butanol. The variation of molecular conductance,, with soap concentration, C, is expressed by the equation: = 10^AC^B. Both constants A and B vary with solvent composition but B remains constant with increase in temperature. Several parameters such as molecular conductance at infinite dilution, , dissociation constant, K, heat of dissociation, H, entropy, S and free energy, G of dissociation of soap have been evaluated and the effect of the nature of solvents has been discussed.     

Sedimentation equilibrium of suspensions of colloidal particles at finite concentrations

Equilibrium concentration profiles of non-dilute colloidal suspensions are calculated by means of the Carnahan-Starling expression for the osmotic compressibility of hard sphere liquids. The profiles depend on the average volume fraction of the suspension, , and on the field interaction parameter, ₀ (reciprocal of the Péclet number at infinite dilution). Profiles are computed for values of and ₀ typical of those encountered in sedimentation field-flow fractionation experiments. It is found that, in most cases, the volume fraction at the depletion wall is negligibly small and that the volume fraction at the accumulation wall ₀, depends on the ratio <>₀/₀ only. An inflexion point is found in the concentration profile if ₀ is larger than 0.13 whatever the value of ₀.     

Negativer linearer thermischer Ausdehnungskoeffizient von verstrecktem Polyäthylen

Zusammenfassung Der lineare thermische Ausdehnungskoeffizient von linearem Polyäthylen hoher Dichte wurde im Temperaturbereich –20 °C bis + 40°C bestimmt. Bei isotropen Proben besteht eine lineare Beziehung zwischen Dichte bzw. Kristallisationsgrad _v und. Die gemessenen Koeffizienten liegen fürT ₀ = 20 °C im Bereich = 110 ... 130 · 10^–6 K^–1.Kalt verstreckte Proben mit Verstreckungsgraden = 8 ... 15 haben beiT ₀ = 20 °C in Verstreckrichtung den Koeffizienten _l = –24 · 10^–6 K^–1. Der negative Zahlenwert von _tl ist unabhängig von und weiteren Herstellungsparametern. Seine Ursache ist einerseits die Orientierung derc-Achsen der Kristallite in Verstreckrichtung mit _c = –12 · 10^–6 K^–1 und andererseits der negative Koeffizient _am * –50 · 10^–6 K^–1 der verspannten amorphen Phase, der auf dem gummielastischen Verhalten der tie-molecules beruht.Beim Tempern oberhalb von +40 °C schrumpfen die Proben irreversibel, wobei _| ansteigt und nach dem Aufschmelzen der Proben wieder den Wert des isotropen Materials annimmt. Nach dem Tempern wenig unterhalb der Schmelztemperatur der Kristallite wurden überhöhte Koeffizienten _| gemessen, die eine Rotation der Kristallite um dieb-Achsen erkennen lassen.

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Summary The linear thermal coefficient of expansion,, of high density linear polyethylene has been determined in the temperature range of –20 ° ... + 40 °C. For isotropic samples a linear relationship between density or crystallinity _v and is valid. Measured values of forT ₀ = 20 °C amount to = 110 ... 130 · 10^–6 K^–1.Cold drawn samples of draw ratios = 8 ... 15 yield _| = –24 · 10^–6 K^–1 atT ₀ = 20 °C parallel to the draw axis. The negative value of _| does not depend on draw ratio or other parameters of sample processing. It is caused byc-axis orientation of the crystallites in draw direction with _c = –12 · 10^–6 K^–1 and by a negative coefficient _am * = –50 · 10^–6 K^–1 of the stressed amorphous phase, which is due to rubber elastic behaviour of the tie molecules.When annealed above 40 °C the samples shrink irreversibly and _| is augmented. After melting the samples the value of isotropic material is restored. Annealing the samples little below the melting temperature of the crystallites leads to superelevated values all which reflect| rotation of the crystallites around theb-axis.

     

Principal vectors of crystallographic groups and applications

For a crystallographic group acting on ann-dimensional Euclidean space we consider the -invariant linear elliptic differential operatorP with constant coefficients and to it the -automorphic eigenvalue problemP [] + = 0. N() is the number of all eigenvalues smaller than or equal to the frequency bound ^q (q: order ofP). Earlier we found the asymptotic estimationN() c₀ · ⁿ + c₁ · ^n–1 (c ₀,c ₁: certain volumina). Furthermore,N() was interpreted as the number of so-called principal classes of principal lattice vectors within a convex domain. In this paper we demonstrate these results for the casen = 2 for two representative crystallographic groups and the assigned lattices. Above all we demonstrate a counting method for an exact estimation ofN() if a is not too big. In an analogous way we can treat all the 230 space groups of crystallography. It will be seen that these applications are brought about by the so-called principal vectors of these lattices.     

Thermal decomposition of the pyridinium salt of 1,3-bis(trimethylsilyl)-2,4-dimercapto-2,4-dithioxo-1,3-diaza-2λ5, 4λ5-diphosphetidine

It was found that the first step of thermal decomposition of the pyridinium salt of 1,3-bis(trimethylsilyl)-2, 4-dimercapto-2,4-dithioxo-1,3-diaza-2⁵,4⁵-diphosphetidine (I) most probably involves breakdown to the acid form HS(S)P(NHSiMe₃)₂P(S)SH (II). The latter is very unstable and decomposes further, the end-product being a polymer (PNS)_x. In this work, the mechanism of this process is investigated.

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Zusammenfassung Man fand, daß der erste Schritt der thermischen Zersetzung des Pyridiniumsalzes von 1,3-Bis(trimethylsilyl)-2,4-dimercapto-2,4-dithioxo-1,3-diaza-25,45-diphosphetidin (I) sehr wahrscheinlich einen Abbau zur Säureform HS(S)P(NHSiMe₃)₂P(S)SH (II) beinhaltet. Letztere ist sehr unbeständig und zersetzt sich, wobei als Endprodukt ein (PNS)_x-Polymer entsteht. In vorliegendem Manuskript wird der Mechanismus dieses Prozesses näher untersucht.

     

On the Interaction of Two Finite-Dimensional Quantum Systems

Interaction of quantum system S ^a described by the generalised × eigenvalue equation A| _s =E _s S ^a | _s (s=1,...,) with quantum system S ^b described by the generalised n×n eigenvalue equation B| _i = _i S ^b | _i (i=1,...,n) is considered. With the system S ^a is associated -dimensional space X ^a and with the system S ^b is associated an n-dimensional space X _n ^b that is orthogonal to X ^a . Combined system S is described by the generalised (+n)×(+n) eigenvalue equation [A+B+V]| _k = _k [S ^a +S ^b +P]| _k (k=1,...,n+) where operators V and P represent interaction between those two systems. All operators are Hermitian, while operators S ^a ,S ^b and S=S ^a +S ^b +P are, in addition, positive definite. It is shown that each eigenvalue _{k i} of the combined system is the eigenvalue of the × eigenvalue equation . Operator in this equation is expressed in terms of the eigenvalues _i of the system S ^b and in terms of matrix elements _s |V| _i and _s |P| _i where vectors | _s form a base in X ^a . Eigenstate | _k ^a of this equation is the projection of the eigenstate | _k of the combined system on the space X ^a . Projection | _k ^b of | _k on the space X _n ^b is given by | _k ^b =( _k S ^b –B)^–1(V– _k P})| _k ^a where ( _k S ^b –B)^–1 is inverse of ( _k S ^b –B) in X _n ^b . Hence, if the solution to the system S ^b is known, one can obtain all eigenvalues _{k i} } and all the corresponding eigenstates | _k of the combined system as a solution of the above × eigenvalue equation that refers to the system S ^a alone. Slightly more complicated expressions are obtained for the eigenvalues _{k i} } and the corresponding eigenstates, provided such eigenvalues and eigenstates exist.     

Solvent extraction and spectrophotometric including graphite furnace atomic absorption determination of molybdenum in the environment

A selective and sensitive method for the extraction and microgram determination of molybdenum (VI) with hydroxamic acid as yellow molybdenum-hydroxamate complex from acidic medium is described. The molybdenum-PCPPSAHA complex has _max 388 nm, molar absorptivity 5.0 × 10³l mol^–1 cm^–1. The system obeys Beer's law in the range of 1–28 g/ml of molybdenum(VI). Sandell's sensitivity is 0.0192 g cm² and stoichiometry of the complex is 12, molybdenum: PCPPSAHA while mixed complex molybdenum-PCPPSAHA-morin has _max 400 nm and molar absorptivity 5.9 × 10³lmo1^–1 cm^–1 and stoichiometry of the complex is 121.The molybdenum is determined by graphite furnace atomic absorption spectrophotometry after directly pipetted the extract into the furnace which increases the sensitivity 20 fold.     

A turbidity study of particle interaction in latex suspensions

A turbidimetric analysis of particle interaction in latex suspensions is given. The turbidity measured at different wavelengths can be rendered by the product of an integrated form factorQ(²) and a suitably defined integrated structure factorZ(²,c). This factorization rests on the expansion of the form factor of the particlesP(q) and the structure factorS(q) [q=(4/)sin(/2); : scattering angle] of the system in even powers ofq. The accuracy of this approximation has been shown by calculating the turbidity for a system of hard spheres in terms of the Percus-Yevick structure factor by numerical integration. Also, the effect of polydispersity has been taken into account within the frame of Percus-Yevick-Vrij theory for non-uniform hard spheres. It is shown that the influence of small polydispersity (standard deviation below 8%) is within experimental uncertainty. The method is applied to precise UV-spectra (400800 nm) obtained from a polystyrene latex with a diameter of 77.4 nm. The integrated structure factorZ(²,c) obtained experimentally can be interpreted in terms of an effective diameter of interaction giving a measure for the strength of electrostatic interaction.     

Crystallite sizes and paracrystalline lattice distortions in drawn hard elastic polypropylene

Summary The paracrystalline lattice distortions and the mosaic crystallite sizeD ₀₀₁ are constant at all draw ratios ( =1 ... 2,3) of a hard elastic polypropylene foil. The lateral crystallite sizes decrease sharply (but not much) at a small draw ratio and slow to higher .

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Zusammenfassung Beim Verstrecken einer hartelastischen Polypropylen-Folie (Verstreckgrade =1 ... 2,3) bleiben die parakristallinen Gitterstörungen und die MosaikkristallitgrößeD ₀₀₁ konstant. Die lateralen Kristallitgrößen nehmen bei kleinem A steil, aber wenig, ab und verringern sich dann langsam weiter mit wachsendem .

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With 2 figures     

Pyrocatechol-1-aldehyde salicyloylhydrazone as reagent for the spectrofluorimetric determination of zinc

Summary A procedure is developed for the Spectrofluorimetric determination of 10–800 ppb of zinc with pyrocatechol-1-aldehyde salicyloylhydrazone in a 60% (v/v) ethanol-water medium at apparent pH 6.7 (acetic-acetate buffer). _ex=400 nm, _em=530 nm. Interferences have been evaluated and the method applied to the determination of zinc in alloys and lubricating oils.

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Spektrofluorimetrische Bestimmung von Zink mit Brenzcatechin-1-aldehyd-salizyloylhydrazon

Zusammenfassung Zink bildet mit Brenzcatechin-1-aldehyd-salizyloylhydrazon ein gelbes, fluoreszierendes Chelat in Gegenwart von 60% Ethanol bei pH 6,7 (Essigsäure-Natriumacetat-Puffer); _ex=400 nm, _em=530 nm. Zwischen Intensität der Fluoreszenz und Zink-Konzentration besteht im Bereich von 10 bis 800 ppb Linearität. Das Verfahren wurde zur Bestimmung des Zinks in Legierungen und Schmierölen verwendet.

     

Fluorimetric determination of 1-naphthol and mixtures of carbaryl and 1-naphthol in micellar media

Summary The interaction of 1-naphthol with different types of anionic, cationic and non-ionic surfactants has been studied spectrofluorimetrically in order to obtain a sensitivity enhancement in the determination of this compound. At neutral pH, cetyl trimethyl ammonium bromide (CTAB) provides a 2-fold sensitivity enhancement of 1-naphthol and exhibits a weak interaction with carbaryl. In strong alkaline medium carbaryl is hydrolyzed to 1-naphthol and in the presence of CTAB micells, a 5-fold sensitivity enhancement and a limit of detection of 0.2 g·ml^–1 with a 101±3% percentage of recovery is obtained. These facts permit the development of an accurate method for the fluorimetric analysis of 1-naphthol and carbaryl mixtures, comprising the determination of the sum of both compounds (pH 12, 0.1% w/v CTAB, _em=449 nm, _ex=341 nm) and of the concentration of 1-naphthol (neutral pH, 0.4% w/v CTAB, _em=449 nm, _ex=312 nm).     

Interaction of PM12?nVnO40?(3+n) (M=Mo, W) heteropoly complexes with nitrogen oxide

In aqueous solution, PM_12–nV_nO₄₀ ^–(3+n) (M=Mo,W) hetero-polyanions provide a much faster oxidation of NO than mononuclear VO ₂ ⁺ ions, yielding HNO₂, NO ₃ ^– and reduced HPA.

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, PM_12–nV_nO₄₀ ^–(3+n) (M=Mo,W) , VO ₂ ⁺ , NO HNO₂ NO ₃ ^– .