Influence of structural promoters on reduction dilatograms of iron catalyst

In each reduction step, changes in the catalyst pellet volume during reduction of precipitated iron catalysts are determined by the concentration of structural promoters and the reaction temperature.

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, , .

     

Molecular Recognition Based on Roof-shaped Diol Hosts. X-Ray Crystal Structures of Inclusion Compounds with Methanol, Pyridine and Toluene

Three crystalline inclusion compounds of roof-shapedtrans-11,12-bis(diaryl-hydroxymethyl)-9,10-dihydro-9,10-ethanoanthracene host molecules [where aryl is 4-methyl-phenyl (3) or4-t-butylphenyl (4)] have been studied by X-ray diffraction.The crystals of both the 3methanol (2 : 1) [a = 10.755(1),b = 11.571(1), c = 14.697(2) Å, = 75.12(1), = 89.67(1), = 87.13(1) °] and the 4-pyridine (2 : 3) compounds[a = 14.045(3), b = 14.366(3), c = 15.607(3) Å, = 91.62(1), = 103.65(1) and =116.05(1)°] are triclinic (P–1),while the 3toluene (1 : 1) complex has orthorhombic (Fddd) symmetry [a = 16.041(1), b = 25.008(1), c = 40.440(4) Å]. The host–guest interactions in both triclinic crystals are characterised by hydrogen bonds, with different patterns however. The determined crystal structures indicate a compromise between the requirement of hydrogen bonding on the one hand and close packing on the other. The highly symmetrical host framework in the toluene (1 : 1) complex of 3 seems to be the result of shape recognition, although atendency towards weak (C_methyl)H _arylinteractions [C_methyl = 3.533(7) and 3.674(6) Å] between the hosts was observed. The present roof-shaped diol hosts give excellent examples of molecular recognition by exhibiting two significantly different conformations, mostly depending on the proton donor/acceptor ability of the guest component. (O)H O intramolecular bonding between the two alcoholic groups characterises the so-called active form, whereas weaker (O)H and interactions stabilise the `inactive'conformation.     

Inclusion Compounds of Thiourea and Peralkylated Ammonium Salts. Part V. Hydrogen-Bonded Host Lattices Built of Thiourea and Acetate Ions

New inclusion complexes (C2H5)4N+CH3CO-°*4(NH2)2CS(1), (n-C3H7)4N+[(CH3CO2)2H]-°2(NH2)2CS (2), (n-C4H9)4N+[(CH3CO2)2H]-°2(NH2)2CS (3) and (CH3)4N+CH3CO2-°(NH2)2CS(4) have been prepared and characterized by X-raycrystallography. Crystal data, MoK radiation: 1, space groupC2/c, a = 28.702(4), b = 8.457(1), c =22.906(7) Å, = 98.91(1)°, Z = 8, and RF = 0.048for 2587 observed data; 2, space group P2/n, a = 8.536(2), b = 8.613(1), c = 18.360(2) Å, = 90.66(2)°, Z = 2, and RF = 0.045 for 1637 observed data; 3,space group P¯1, a = 8.771(3), b = 10.720(1), c = 16.742(2) Å, = 99.08(6), = 94.07(2), = 95.25(2)°, Z = 2, and RF = 0.063 for 2736 observed data; 4, space group P21/n, a = 8.421(3), b = 16.532(6), c = 8.628(3) Å, = 90.25(3), Z = 4, and RF = 0.050 for 1507observed data. In the crystal structure of 1, the thiourea moleculesand acetate ions constitute two channel systems aligned parallel to the[110] and [¯110] directions, with thetetraethylammonium cations accommodated in a single column withineach channel. In the crystal structure of 2, hydrogen-bondedcentrosymmetric thiourea dimers and acetate dimers are alternatelyarranged to form a zigzag, puckered ribbon running parallel to [10¯¯1], and the stacked columns of cations are sandwichedbetween undulatory wave layers constructed from the parallelarrangement of [((NH2)2CS)2((CH3CO2)2H)-] ribbons. In the crystal structure of 3,zigzag hydrogen-bonded thiourea ribbons are linked by dimeric acetateanions existing in two different conformations to generate puckeredlayers matching the (002) planes, and the (n-C4H9)4N+ cations occupy the intervening space. Incompound 4 the cations are accommodated in pseudo-channelsgenerated from infinitely extended thiourea-acetate composite ribbons.     

Polymorphism of Crystalline Inclusion Complexes and Unsolvated Hosts. Part 8

Crystallization of cyclotriveratrylene (CTV) from solutions in acetone at 40°C gave a new 4:1 host-guest complex instead of the conventional 2:1 clathrate (-phase) whose X-ray crystal structure was determined. Data for 2(C₂₇H₃₀O₆) · 0.5(CO(CH₃)₂): monoclinic, P2₁/c, a = 18.942(4), b = 24.697(5), c = 10.508(2) Å, = 91.10(2)°, V = 4915(2) ų, Z = 8, D _x = 1.257 g/cm³, T = 293 K, R = 0.077 (for 2694 reflections). One of the two crystallographically independent CTV molecules (molecule A) is stacked into columns characteristic of the CTV - or -phase complexes. Molecules B face each other enclathrating inside around the inversion center disordered acetone molecules giving rise to the molecular capsule. The acetone molecule is H-bonded simultaneously to both host molecules by C(H₂)--H ··· O type bonds forming centrosymmetric dimers. Dimers are incorporated together with two A molecules into centrosymmetric units also by C(H₂)--H ··· O type H-bonds. Packing of these units gives rise to the crystal structure of the clathrate.     

X-Ray Crystal Structure of Four Inclusion Complexes of the Novel Host Gossindane: An Oxidation Product of Gossypol

Gossindane, the oxidation product of gossypol, demonstrates inclusion properties towards four solvents chosen accidentally. The crystal data of these complexes with ethanol (I), ethylacetate (II), dichloromethane (III) and water (IV) are: (I): C26H30O6· 2C2H5OH, monoclinic, P2/c, a = 8.687(2) Å, b = 10.986(3) Å, c = 14.778(3) Å = 110.94° V = 1317 Å3, Z = 2, R = 0.069, N = 1368; (II): C26H30O6· 0.5C4H8O2, monoclinic, P21/c, a = 8.960(2) Å, b = 21.937(5) Å, c = 14.712(3) Å, = 111.98(2)°, V = 2681 Å3, Z = 4, R = 0.083, N = 2653; (III): C26H30O6· CH2Cl2, monoclinic, P21/c, a = 8.886(2) Å, b = 21.778(6) Å, c = 14.996(4) Å, = 111.31(3)°, V = 2704 Å3, Z = 4, R = 0.131, N = 1580; (IV): C26H30O6·2H2O, monoclinic, C2/c, a = 29.422(9) Å, b = 6.720(2) Å, c = 27.525(9) Å, = 117.43(2)°, V = 4830 Å3, Z = 8. R = 0.096, N = 2240.In the solvates H-bonded host molecules form bilayers with very similar structures and a nearly hydrophobic surface. Guest molecules are placed in channels formed between these bilayers and may be H- bonded to host molecules (ethanol). In the hydrate two water molecules using their H-bonding capacity incorporate gossindane molecules into bilayers.     

VUV-Photolyse von Methanol bei 1236 Å

Zusammenfassung Es wird über die indirekte und die direkte VUV-Photolyse von luftfreiem Methanol in flüssiger Phase bei 1236 Å berichtet. Bei der Bestrahlung von wäßr. 0,01m-Methanol wurden folgende Produkte und Ausbeuten erhalten: (H₂)=1,00, (HCHO)=0,27, (CH₂OH)₂=0,12, (CH₂OH·CHO)=0,04 und (HCOOH)=0,02. Die Photolyse von flüssigem Methanol lieferte die gleichen Produkte, jedoch mit höheren Ausbeuten: (H₂)=1,50, (HCHO)=0,98, (CH₂OH)₂=0,28 und (CH₂OH·CHO)=0,06. Unter Anwendung von Methanol als Radikalfänger konnte auch die Quantenausbeute der Wasserphotolyse bei 1236 Å, (H,OH)=1,025 verifiziert werden. Wahrscheinliche Reaktionsmechanismen werden diskutiert.

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V.U.V.-Photolysis of methanol at 1236 Å

The indirect and the direct v.u.v.-photolysis of air free methanol in liquid phase at 1236 Å is reported. After irradiation of aqueous 0.01M-methanol the following products were obtained: (H₂)=1.00, (HCHO)=0.27, (CH₂OH)₂=0.12, (CH₂OH·CHO)=0.04 and (HCOOH)=0.02. The photolysis of liquid methanol yielded the same compounds, however with higher amount as follows: (H₂)=1.50, (HCHO)=0.98, (CH₂OH)₂=0.28 and (CH₂OH·CHO)=0.06. Using methanol as a scavenger for the H and OH radicals the quantum yield of the water photolysis at 1236 Å could be verified to be (H,OH)=1.025. Probable reaction mechanisms are discussed.

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Mit 3 Abbildungen

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Herrn Prof. Dr.E. Broda zum 60. Geburtstag gewidmet.     

Influence of Pr ions on the properties of Pd/SiO2 and Pt/SiO2 catalysts in oxidation of n-butane

It has been established that (M_VIII+Pr)/SiO₂ catalysts (M_VIII=Pd or Pt) obtained from organometallic precursors, have increased the dispersity of Pt, but their TN in deep oxidation of n-butane is by 3–6 times lower than that of unmodified M_VIII/SiO₂.

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(M_VIII+Pr)/SiO₂ ( M_VIII=Pd, Pt), , Pt, 3–6 - M_VIII/SiO₂.

     

Thermal decomposition of [Co(NH3)6]Cl3

The thermal decomposition reactions of [Co(NH₃)₆]Cl₃ were determined in dynamic argon and air atmospheres. The investigations were carried out with simultaneous TG-DTG-DTA measurements under non-isothermal conditions, thermogravimetry under quasi-isothermal conditions, reflectance spectroscopy, absorption spectroscopy, X-ray diffraction and chemical analysis. The data show that the thermal decomposition of [Co(NH₃)₆]Cl₃ occurs in three and four stages in argon and air atmospheres, respectively. The determined sequences are in agreement with that proposed by Simons and Wendlandt [2, 5].The changes in the morphology of the studied complex crystalline powder in the course of thermal decomposition in air were followed by scanning electron microscopy.

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Zusammenfassung In bewegter Argon- und Luftatmosphäre wurden die Zersetzungsreaktionen für [Co(NH₃)₆]Cl₃ bestimmt. Zu den Untersuchungen wurden folgende Methoden zu Hilfe gezogen: simultane TG-DTG-DTA-Messungen unter nichtisothermen Bedingungen, Thermogravimetrie unter quasi-isothermen Bedingungen, Remissionsspektroskopie, Absorptionsspektroskopie, Röntgendiffraktion und chemische Analyse. Die Ergebnisse zeigen, daß sich [Co(NH₃)₆]Cl₃ in Argon in drei und in Luft in vier Schritten thermisch zersetzt. Die festgestellten Sequenzen stehen in Übereinstimmung mit den von Simon und Wendlandt [2, 5] vorgeschlagenen. Veränderungen in der Morphologie des untersuchten Komplexkristallpulvers wurden über die thermische Zersetzung in Luft mittels Scanning-Elektronen-Mikroskopie beobachtet.

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[Co(NH₃)₆]Cl₃. , , - , , , . , , , , , , .

     

Kinetics of catalytic oxidation of aliphatic alcohols in aqueous alkaline solutions of copper phenanthroline complexes

The effect of Cu(II), phenanthroline, alcohol, NaOH and O₂ concentrations on the oxidation rates of alcohols in aqueous alkaline solutions has been studied and a reaction mechanism is proposed.

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Cu(II), , , NaOH, O₂ - . .

     

Kinetics and selectivity of the oxidation of alkanes in Cl2?H2O and Cl2?Hg2+?H2O solutions

Relative oxidation rate constants of several normal, iso-, cyclo-and methylcycloalkanes have been measured in Cl₂–H₂O and Cl₂–Hg²⁺–H₂O solutions at 343K. The selectivity of C–H bond dissociation in both systems is the same. HOCl is assumed to be the active species for the two systems.

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Cl₂–H₂O Cl₂–Hg²⁺–H₂O 343 , -,- ; C–H . , HOCl.

     

Effect of medium composition on the monooxygenase activity of immobilized hemin in aniline oxidation

The effect of the composition of the reaction medium on the rate of aniline oxidation to p-aminophenol by hydrogen peroxide on hemin immobilized on -propylimidazole-modified silica has been studied. Organic solvent additives (alcohols, esters and nitriles) are shown to increase the reaction rate. The observed effect is attributed to the decrease of the medium dielectric constant.

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- , , --. , (, , ) . .

     

Zwitterionic [(H3NCH2C≡CC≡CCH2NH3)]Cu2Cl4 π-Complex: Template Synthesis and Crystal Structure

Crystals of the [(H₃NCH₂CCCCCH₂NH₃)]Cu₂Cl₄ -complex, formed in the oxidative dimerization of propargylammonium cations, were obtained by ac electrochemical synthesis from CuCl₂ · 2H₂O and propargylammonium chloride ([CCCH₂NH₃]Cl) and studied by X-ray diffraction analysis (DARCh automated diffractometer, MoK radiation, /2 scan mode; 2275 reflections with F 4(F), R = 0.048). Crystals are monoclinic: space group B2/b, a = 19.591(6) Å, b = 7.299(3) Å, c = 8.636(3) Å, = 106.83(3)°, Z = 4. The structure consists of individual [(H₃NCH₂CCCCCH₂NH₃)]Cu₂Cl₄ moietes united through the elongated Cu···Cl contacts (2.827(5) Å) into chains oriented along the [010] direction. The bond of the centrosymmetric propargylammonium dimer is -coordintated by copper(I) atom and is elongated to 1.227(6) Å.     

Inclusion complexes of the natural product gossypol. Strong influence of the guest on the host structure in channel-type isostructural inclusion complexes of gossypol

The crystal structures of 1 : 1 inclusion complexes of gossypol with tetrahydrofuran (GPTHF), cyclohexanone (GPCHN) and butanal (GPBTA) have been determined by X-ray structure analysis. The crystals of GPTHF are triclinic, space group P,a = 10.788(2),b = 10.979(3),c = 13,880(2) Å, = 80. 11(2), = 103.87(1), = 77.96(2)°,V = 1517.8(6) ų,Z = 2,R = 0.052 for 2701 observed reflections. The crystals of GPCHN are triclinic, space groups P,a = 10.803(4),b = 11.157(5),c = 15.428(6) Å, = 108.75(3), = 106.93(3), = 103.34(3)°,V = 1573(1) ų,Z = 2,R = 0.071 for 1879 observed reflections. The crystals of GPBTA are triclinic, space group P,a = 10.190(2),b = 11.335(1),c = 14.665(2) Å, = 73.04(1), = 103.74(1), = 81.07(1)°,V = 1529.9(5) ų,Z = 2,R = 0.068 for 2964 observed reflections. Crystal data for another 13 isostructural inclusion complexes are given.[/p]In this isostructural group of complexes guest molecules are accommodated in channels and are hydrogen bonded to the host molecules via an 0(1)-H....O(1) hydrogen bond. The molecular association changes significantly with the shape and size of the guest component. In GPTHF centrosymmetric dimers of gossypol formedvia O(5)-H...O(3) hydrogen bonds are associated in columns via a weak O(4)-H...O(8) hydrogen bond. In GPCHN the latter bond disappears as the distance O(4)-O(8) is increased to 3.73 Å. In GPBTA the O(5)-H...O(3) bond is replaced by three centre hydrogen bonds O(5)-H...O(2) and O(3)-H...O(5), and a centrosymmetric dimer of a new type is formed. These dimers are further connected by two weak hydrogen bonds to form columns. The butanal molecule interacts with the host structure via two hydrogen bonds. This indicates that a guest component can activate or deactivate different functional groups of the host in channel inclusion complexes of gossypol for hydrogen bond formation.     

On the crystal chemistry of three copper(II)-arsenates: Cu3(AsO4)2-III,Na4Cu(AsO4)2, and KCu4(AsO4)3

The three copper(II)-arsenates were synthesized under hydrothermal conditions; their crystal structures were determined by single-crystal X-ray diffraction methods:Cu₃(AsO₄)₂-III:a=5.046(2) Å,b=5.417(2) Å,c=6.354(2) Å, =70.61(2)°, =86.52(2)°, =68.43(2)°,Z=1, space group ,R=0.035 for 1674 reflections with sin / 0.90 Å^–1.Na₄Cu(AsO₄)₂:a=4.882(2) Å,b=5.870(2) Å,c=6.958(3) Å, =98.51(2)°, =90.76(2)°, =105.97(2)°,Z=1, space group ,R=0.028 for 2157 reflections with sin / 0.90 Å^–1.KCu₄(AsO₄)₃:a=12.234(5) Å,b=12.438(5) Å,c=7.307(3) Å, =118.17(2)°,Z=4, space group C2/c,R=0.029 for 1896 reflections with sin / 0.80 Å^–1.Within these three compounds the Cu atoms are square planar [4], tetragonal pyramidal [4+1], and tetragonal bipyramidal [4+2] coordinated by O atoms; an exception is the Cu(2)^[4+1] atom in Cu₃(AsO₄)₂-III: the coordination polyhedron is a representative for the transition from a tetragonal pyramid towards a trigonal bipyramid. In KCu₄(AsO₄)₃ the Cu(1)^[4]O₄ square and the As(1)O₄ tetrahedron share a common O—O edge of 2.428(5) Å, resulting in distortions of both the CuO₄ square and the AsO₄ tetrahedron. The two Na atoms in Na₄Cu(AsO₄)₂ are [6] coordinated, the K atom in KCu₄(AsO₄)₃ is [8] coordinated by O atoms.Die drei Kupfer(II)-Arsenate wurden unter Hydrothermalbedingungen gezüchtet und ihre Kristallstrukturen mittels Einkristall-Röntgenbeugungsmethoden ermittelt:Cu₃(AsO₄)₂-III:a = 5.046(2) Å,b = 5.417(2) Å,c = 6.354(2) Å, = 70.61 (2)°, = 86.52(2)°, = 68.43(2)°,Z = 1, Raumgruppe ,R = 0.035 für 1674 Reflexe mit sin / 0.90 Å^–1.Na₄Cu(AsO₄)₂:a = 4.882(2) Å,b = 5.870(2) Å,c = 6.958(3) Å, = 98.51(2)°, = 90.76(2)°, = 105.97(2)°,Z = 1, Raumgruppe ,R = 0.028 für 2157 Reflexe mit sin / 0.90 Å^–1.KCu₄(AsO₄)₃:a = 12.234(5) Å,b = 12.438(5) Å,c = 7.307(3) Å, = 118.17(2)°,Z = 4, Raumgruppe C2/c,R = 0.029 für 1896 Reflexe mit sin / 0.80 Å^–1.Die Cu-Atome in diesen drei Verbindungen sind durch O-Atome quadratisch planar [4], tetragonal pyramidal [4 + 1] und tetragonal dipyramidal [4 + 2]-koordiniert; eine Ausnahme ist das Cu(2)^{[4 + 1]}-Atom in Cu₃(AsO₄)₂-III: Das Koordinationspolyeder stellt einen Vertreter des Übergangs von einer tetragonalen Pyramide zu einer trigonalen Dipyramide dar. In KCu₄(AsO₄)₃ haben das Cu(1)^[4]O₄-Quadrat und das As(1)O₄-Tetraeder eine gemeinsame O—O-Kante von 2.428(5) Å, was eine Verzerrung der beiden Koordinationsfiguren CuO₄-Quadrat und AsO₄-Tetraeder bedingt. Die zwei Na-Atome in Na₄Cu(AsO₄)₃ sind durch O-Atome [6]-koordiniert, das K-Atom in KCu₄(AsO₄)₃ ist [8]-koordiniert.

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Zur Kristallchemie dreier Kupfer (II)-Arsenate: Cu₃(AsO₄)₂-III, Na₄Cu(AsO₄)₂ und KCu₄(AsO₄)₃

     

Charge-transfer Interaction: A Driving Force for Cyclodextrin Inclusion Complexation

PM3 calculations were performed on the complexation of -cyclodextrin (-CD) with nitrobenzene, benzoic acid, benzoate anion, 4-nitrophenol, and 4-nitrophenolate anion. The results, in agreement with the experimental observations, indicated that the complex -CD-benzoic acid was more stable than -CD-nitrobenzene, and -CD-4-nitrophenolate was more stable than -CD-4-nitrophenol. Frontier orbital analysis suggested that charge-transfer interaction led to such behaviors, and hence constituted a nontrivial driving force in the molecular recognition of -CD.     

Calculation of the energy spectrum of surface oxygen on CuO by the interacting bonds method

Using the interacting bonds model a calculation has been made for the energy spectrum of oxygen on the CuO surface. Dissociative adsorption of oxygen can be realized in one and two-center forms with 9.2 and 60.4 kcal/mol, respectively. Intermediate values of the adsorption heats are attributed to oxygen adsorption on induced and biographic defects. The theoretically calculated energy spectrum of adsorbed oxygen is in reasonable agreement with that obtained experimentally from the dependence of isosteric heats of oxygen adsorption on the surface coverage.

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CuO. - 9,2 60,4 / . . .

     

Crystallization of iron phosphate glasses

Differential thermal analysis (DTA), thermogravimetric analysis (TG), X-ray diffraction and Mössbauer spectroscopy were employed in the investigation of crystalline products of FeO_x-P₂O₅ glasses generated by various heat treatments. In glasses with a high value of =Fe²⁺/(Fe²⁺ + Fe³⁺), absorption of oxygen occurs in a broad temperature range identified by TG. Depending on the value of , two exotherms appear in the DTA curves, the low-temperature one corresponding to crystallization of the Fe₃(PO₄)₂ type regions, and the high-temperature one being related to various phases with dominating FePO₄. Each exotherm has its own transformation region, identical in absolute value. The Mössbauer spectra of glasses which underwent thermal treatment at higher temperatures exhibit some indication of phases of the types Fe₃(PO₄)₂ · xH₂O and FePO₄ · xH₂O.

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Zusammenfassung Differentialthermoanalyse (DTA), thermogravimetrische Analyse (TG), Röntgendiffraktion und Mössbauerspektroskopie wurden bei der Untersuchung (von kristalliner Produkte) durch verschiedene thermische Behandlungen hergestellten FeO_x-P₂O₅ Gläsern eingesetzt. In den Glasarten mit einem hohen Wert von =Fe²⁺/(Fe²⁺ + Fe³⁺) erfolgt die Sauerstoffabsorption in einem durch TG [nachgewiesenen breiten Temperaturbereich. In Abhängigkeit von dem -Wert erscheinen zwei Exothermen in den DTA-Kurven, von denen der bei niedriger Temperatur die Kristallisation des Fe₃(PO₄)₂ entspricht, und jener bei höheren Temperaturen in verschiedenen Phasen dem FePO₄. Jede Exotherme hat ihr eigenes Umwandlungsgebiet, das in absolutem Wert identisch ist. Die Mössbauer-Spektren der Gläser welche einer Wärmebehandlung bei höheren Temperaturen unterzogen worden sind, weisen einige Indikationsphasen der Typen Fe₃(PO₄)₂ · xH₂O und FePO₄ · xH₂O auf.

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, , FeO_x-P₂O₅, . , =Fe²⁺/(Fe²⁺+Fe³⁺) . , - : Fe₃(PO₄)₂, – FePO₄. , . , , Fe₃(PO₄)₂ · ₂ FePO₄ · ₂.

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The authors thank Mrs. Simonyiová for assistance in the experimental part of these investigations, and Dr. Horváth and Dr. Vondrovic for performing the X-ray and TG analyses.     

On the catalytic system MgO?Na

Acid-base and radical properties of two sets of MgO–Na catalysts have been studied. The catalysts were prepared (I) by impregnation of MgO with NaOH in aqueous solution, and (II) by evaporation of metallic sodium onto a MgO surface. The catalyst prepared by the second method was much more basic than pure MgO (H_o=35) and showed a high activity in olefin isomerization.

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- MgO–Na. 1) MgO (NaOH) 2) MgO. , , , MgO(H₀=35), .

     

Thermodynamic Study of the Aqueous Rubidium and Manganese Bromide System

Crystallization of 2RbBr · MnBr₂ · 2H₂O, the only double salt obtained under standard conditions from saturated aqueous rubidium–manganese bromide solutions, was theoretically predicted using the hard and soft Lewis acids and bases concept and Pauling's rules. The RbBr—MnBr₂—H₂O system was thermodynamically simulated by the Pitzer model assuming a solubility diagram of three branches only: RbBr, 2RbBr · MnBr₂ · 2H₂O and MnBr₂ · 4H₂O. The theoretical result was experimentally proved at 25°C by the physicochemical analysis method and formation of the new double salt 2RbBr · MnBr₂ · 2H₂O was established. It was found to crystallize in a triclinic crystal system, space group –P1, a = 5.890(1) Å, b = 6.885(1) Å, c = 7.367(2) Å, = 66.01(1)°, = 87.78(2)°, = 84.93(2)°, V = 271.8(1) ų, Z = 1, D _x = 3.552 g-cm^–3. The binary and ternary ion interaction parameters were calculated and the solubility isotherm was plotted. The standard molar Gibbs energy of the synthesis reaction, _rG _m ^o , of the double salt 2RbBr · MnBr₂ · 2H₂O from the corresponding simple salts RbBr and MnBr₂ · 4H₂O, as well as the standard molar Gibbs energy of formation, _fG _m ^o , and standard molar enthalpy of formation _fH _m ^o of the simple and double salts were calculated.     

Capillary rise of liquids in rectangular tubings

The capillary rise of liquids was investigated in square capillary tubings of different dimensions (e. g. 300 m · 300 m to 1000 m · 1000 m) in the temperature range 25° to 35°C.The data were fitted to an equation:=1/2 · ·g · (S · (C ·H/2 +C ·S)) where is the surface tension of the liquid,S is the side length of the square tubing,H is the capillary rise,C (= 1.089) is a capillary constant.