Diels—Alder reaction between naphthalene and N-phenylmaleimide under mild conditions

The rate and equilibrium constants for the Diels—Alder reactions between benzene or naphthalene and several dienophiles at 25 °C were calculated from the data on the ionization potentials of dienes and electron affinity energies of dienophiles, as well as the reaction enthalpies. The highest yield of the adduct was predicted for the reaction of naphthalene with N-phenylmaleimide. However, the time of its formation in 50% yield exceeds 30 years. The use of gallium chloride as a catalyst affords the endo-adduct for seven days at room temperature in 30% yield. The rate ((2±0.5)·10–6 L mol^–1 s^–1) and equilibrium constants (5±2 L mol^–1) of the reaction were determined.     

Kinetische und thermodynamische Untersuchungen im System AgCl-LiCl-NaCl

In the ternary system silver chloride-lithium chloride-sodium chloride the kinetics of the galvanic deposition of silver on graphite electrodes was investigated as well as its dissolution without current in the molten salt saturated with chlorine gas.In addition the emf-values were measured in the temperature range between 923 K and 1,173 K by means of, the formation cell graphite/Ag(s)/AgCl(l)–LiCl(l)–NaCl(l)/Cl₂ graphite From these data the partial molar free excessGibbs energies were calculated. Using the equation for a multicomponent system as suggested byRedlich-Kister ¹ G _AgCl ^E values were obtained by a non-linear fitting process, where the fit was performed for all investigated temperatures and over the entire concentration range in the ternary system. With the parameters obtained the partial and integral excess valuesG _i ^E ,G ^E ,H _i ^E ,H ^E ,S _i ^E andS ^E were calculated.

     

On the inverse miniemulsion copolymerization and terpolymerization of acrylamide, <Emphasis Type="Italic">N,N′</Emphasis>-methylenebis(acrylamide) and methacrylic acid

The kinetics of free-radical copolymerization and terpolymerization of acrylamide (AAm), N, N′-methylenebis(acrylamide) (MBA) and methacrylic acid (MA) in the inverse water/monomer/cyclohexane/Tween 85 miniemulsion was investigated. Polymerizable sterically-stable miniemulsions were formulated in cyclohexane as a continuous medium. Polymerizations are very fast and reach the final conversion within several minutes. The dependence of the polymerization rate vs. conversion is described by a curve with two nonstationary rate intervals. The maximum rate of polymerization slightly increases with increasing concentration of crosslinking monomer (MBA) and strongly decreases by the addition of MA. The rate of polymerization is inversely proportional to the 0.9 ^th and 1.8 ^th power of the particle concentration without and with MA, respectively. The number of polymer particles is inversely proportional to the 0.18 ^th and 0.13 ^th power of MBA concentration. The kinetic and colloidal parameters of the miniemulsion polymerization are discussed in terms of microemulsion polymerization model.     

Kinetics of electrode reaction coupled to ion transfer across the liquid/liquid interface

In the theoretical model it is assumed that a graphite disk electrode is covered by a thin film of solution of decamethylferrocene (dmfc) and some electrolyte CX in nitrobenzene and immersed in an aqueous solution of the electrolyte MX. Oxidation of dmfc is accompanied by the transfer of anion X ⁻ from water into nitrobenzene since it is also assumed that cations dmfc ⁺ and C ⁺ are insoluble in water and cation M ⁺ is insoluble in nitrobenzene. Kinetic parameters of the electrode reaction can be determined if the total potential difference across the nitrobenzene/water interface is maintained constant by adding the electrolytes CX and MX in concentrations which are much higher than the initial concentration of dmfc in nitrobenzene.     

Removal of <Superscript>60</Superscript>Co<Superscript>2+</Superscript> and <Superscript>137</Superscript>Cs<Superscript>+</Superscript> ions from low radioactive solutions using <Emphasis Type="Italic">Azolla caroliniana</Emphasis> willd. water fern

This study concerns the removal of the ¹³⁷Cs⁺ and ⁶⁰Co²⁺ β+γ-radioactive ions in Azolla caroliniana Willd. water fern. The living fern and two different types of biosorbent prepared from Azolla caroliniana were tested to remove the above-mentioned radioactive ions from dilute solutions, in the absence and in the presence of the ionic competition. Effective ¹³⁷Cs⁺ and ⁶⁰Co²⁺ ions removal from low radioactive wastewaters was demonstrated. The time dependent K _d (t) values were calculated from the absorption data. These results indicate that removal process achieved equilibrium in about 120 min and that it involves two steps: rapid and slow absorption; the active process (metabolic bioaccumulation on the living fern) was responsible for above one half of the total removal process. A thin layer radiochromatography study leads to the conclusion that the biochemical components in which ¹³⁷Cs⁺ and ⁶⁰Co²⁺ place themselves are of a polysaccharide and lipoid fractions.     

Complexes of dioxouranium(VI) with zwitter-ionic forms of Bi- and tetra-dentateSchiff bases

Potentially bi- and tetra-dentateSchiff bases derived from salicylaldehyde react with hydrated uranyl salts to give complexes: UO₂H₂ LX ₂, UO₂H₂ LX ₂ and UO₂(HL)₂ X ₂ [H₂ L=N,N-propane-1,3-diylbis(salicylideneimine), H₂ L=N,N-ethylenebis(salicylideneimine) and HL=N-phenylsalicylideneimine;X ^–=Cl^–, Br^–, I^–, NO₃ ^–, ClO₄ ^–, and NCS^–]. Because of marked spectral similrities with the structurally known Ca(H₂ L) (NO₃)₂, theSchiff bases are coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms of the azomethine groups which carry the protons transferred from phenolic groups on coordination. Halide, nitrate, perchlorate and thiocyanate groups are covalently bonded to the uranyl ion, resulting a 6-coordinated uranium ion in the halo and thiocyanato complexes and 8-coordinated in nitrato and perchlorato complexes.

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Komplexe von Dioxouranyl(VI) mit zwitterionischen Formen von zwei- und vierzähnigen Schiff-Basen

Zusammenfassung Von Salizylaldehyd abgeleitete zwei- und vierzähnigeSchiff-Basen reagieren mit hydratisierten Uranylsalzen zu Komplexen folgenden Typs: UO₂H₂ LX ₂, UO₂H₂ LX ₂ und UO₂(HL)₂ X ₂ [H₂ L=N,N-Propan-1,3-diylbis(salicylidenimin), H₂ L=N,N-Ethylen-bis(salicylidenimin) und HL=N-Phenylsalicylidenimin;X ^–=Cl^–, Br^–, I^–, NO₃ ^–, ClO₄ ^– und NCS^–]. Auf Grund eindeutiger spektraler Ähnlichkeiten mit dem bekannten Ca(H₂ L) (NO₃)₂ wird auf Koordination über die negativ geladenen phenolischen Sauerstoffatome (und nicht über die Azomethin-Stickstoffe) geschlossen. Die AnionenX ^– sind kovalent an das Uranyl-Ion gebunden; damit ergibt sich ein hexakoordiniertes Uranyl-Ion für die Halogen- und Thiocyanat-Komplexe und Oktakoordination für die Nitrat- und Perchlorat-Komplexe.

     

α-酮酯和α-酮酰胺的Henry反应

用三乙胺催化环状α-酮酯和α-酮酰胺同硝基甲烷的Henry反应, 首次合成了12个多官能团的β-硝基醇, 它们的结构用元素分析、红外光谱和核磁共振进行了表征. 这一反应速度较快, 室温下进行, 条件温和, 产率较好, 是合成多官能团硝基醇的有效方法.     

Effect of copper and manganese ions on activities of laccase and peroxidases in three Pleurotus species grown on agricultural wastes

Copper (Cu²⁺) and manganese (Mn²⁺) ions influenced laccase (Lac) and peroxidase production in Pleurotus eryngii, Pleurotus ostreatus, and Pleurotus pulmonarius. In P. eryngii, the optimum Cu²⁺ concentration for Lac production was 1 mM and for peroxidases 10mM, and Mn²⁺ concentration of 5mM led to peaks of Lac and peroxidase activity. In P. ostreatus HAI 493, the highest level of Lac activity was at Cu²⁺ concentrations of 1 and 10 mM and Mn²⁺ concentration of 1mM, respectively. The absence of Cu²⁺ and Mn²⁺ caused the highest levels of peroxidase production. In P. ostreatus HAI 494, the highest level of Lac activity was at a Cu²⁺ concentration of 5 mM and at Mn²⁺ concentration of 1 mM, respectively. High levels of peroxidase activity were found in the medium without and with 1mM Cu²⁺, and at 1 and 5 mM Mn²⁺, respectively. In P. pulmonarius, the highest Lac activity was found in the presence of 5 mM Cu²⁺ and 5 mM Mn²⁺, respectively. The absence of Cu²⁺ and Mn²⁺ as well as their presence at a concentration of 1 mM led to the peaks of peroxidase activities.     

Die Kristallstruktur des Komplexnitrides NbMoN1−x (x≤0,1)

The crystal structure of NbMoN_1–x has been determined from X-ray powder patterns. It is isotypic with the formerly described^1,2 complex nitrides NbCrN and Ta_1–x Cr_1+x N. The tetragonal unit cell contains 6 atoms and belongs to the space groupP4/nmm-D _4h ⁷. The lattice parameters are:a=3,095 Å,c=7,799 Å. The structure is characterized by relatively close packed double layers of Nb-atoms and Mo-atoms parallel to the base plane. The nitrogen atoms are within the octahedral interstitial sites.

     

Konzentrations- und Temperaturabhängigkeit der Viskosität von Polyacrylnitril-Lösungen in Dimethylformamid

Viscosity measurements were carried out with polyacrylonitrile dissolved in dimethylformamide up to 0.36 g/ml. The temperature range was 20°C to 130°C, the highest shear gradient applied, 5.6·10³s^–1. The temperature variation of viscosity is reproduced with sufficient accuracy by the equation =k·exp (Q/RT). Bothk andQ increase as concentration increases, and the viscosity increases withc ^1.12 toc ^6.4 Inverse proportionality appears to exist between concentration and the longest relaxation time.

     

Über Erdalkalimetalloxogallate. VIII Synthese und Aufbau eines neuen Calciumoxogallats: Ca3Ga4O9

The hitherto unknown compound Ca₃Ga₄O₉ was prepared and investigated by X-ray single crystal methods. Ca₃Ga₄O₉ has orthorhombic symmetry:a=1435.8;b=1682.5;c=532.1 pm; space group C _2v ¹¹ –Cmm2,Z=6. The tetrahedra network (circles of 4 and 5 GaO₄-tetrahedra) and the surrounding of Ca²⁺ are described and discussed with respect to other oxogallates.

     

Thermodynamische Untersuchungen ann-Alkan/n-Alkin-Systemen

The vapour-liquid equilibrium data obtained from isobarict-x-measurements have been used for calculation of the group UNIFAC parameters and excess free enthalpyG ^E of binary mixturesn-alkanes with isomericn-alkynes. The UNIFAC model gives satisfactory predictions for the systems studied. The temperature dependence ofG ^E was estimated on the basis of the heats of mixing measured earlier. The influence of the position of triple bond in the molecules ofn-alkynes on the excess thermodynamic functions is considered.

     

Umsetzungen von Metall- und Metalloidverbindungen mit mehrfunktionellen Molekülen, 16. Mitt.

The reaction of trimethylsilylcarbonamides with halogeno-diorganyl-boranes resp. trihalogenoboranes or organodihalogenoboranes gives monomeric resp. dimeric amidoboranes (borylcarbonamides) and derivatives of 4,8-diaza-1,5-dibora-2,6,9-trioxabicyclo[3.3.1]nonadienes. By reaction of the free acylamides with halogenoboranes in most cases the imide halides could be isolated as the only products. By reaction of the hydrochloride of bis(dimethylamino)-hydroxyborane withn-butyl-lithium followed by addition of the imide halides, the corresponding imidoylamines were formed.¹H,¹¹B, and¹⁹F-nmr spectra, mass spectra and characteristic ir group frequencies are reported.

15. Mitt.:W. Maringgele undA. Meller, Z. anorg. allg. Chem., im Druck.     

Synthesis,spectral characterization,redox and antimicrobial activity of Schiff base transition metal(II) complexes derived from 4-aminoantipyrine and 3-salicylideneacetylacetone

A novel tetradentate N₂O₂ type Schiff base, synthesized from 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one(4-aminoantipyrine) and 3-salicylidene-acetylacetone, forms stable complexes with transition metal ions such as Cu ^II , Ni ^II , Co ^II and Zn ^II in ethanol. Microanalytical data, magnetic susceptibility, IR, UV-Vis.,¹H-NMR, ESR and Mass spectral techniques were used to confirm the structures. Electronic absorption spectra of the complexes suggest a square-planar geometry around the central metal ion. These complexes show higher conductance values, supporting their electrolytic nature. The monomeric nature of the complexes was confirmed from their magnetic susceptibility values. Cyclic voltammogram of the copper(II) and nickel(II) complexes in DMSO solution at 300 K were recorded and the results are discussed. The X-band ESR spectra of the copper complex were recorded and the molecular orbital coefficient values were calculated from the spectra. The in vitro antimicrobial activities of the investigated compounds were tested against bacteria such as Klebsiella pneumoniae, Staphylococcus aureus, Bacillus subtilis and Escherichia coli and fungi like Aspergillus niger and Rhizoctonia bataicola. Most of the metal chelates show higher antimicrobial activity for the above microorganisms than that of the free ligand.     

Kinetic and equilibrium study of the deprotonation of 4-nitrophenyl[bis(ethylsulphonyl)]methane by organic bases in acetonitrile in the presence of common cation BH<Superscript>+</Superscript> and tetrabutylammonium perchlorate

The results of kinetic and equilibrium experiments with the set of reaction of proton abstraction from 4-nitrophenyl[bis(ethylsulphonyl)]methane in acetonitrile are reported. Two strong organic bases are used: 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD). The rates of proton transfer reaction have been measured by T-jump method in the presence of perchlorate of the appropriate base as a common cation BH⁺ and supporting electrolyte-tetrabutylammonium perchlorate (TBAP) in the temperature range between 20–40°C are: k _H =1.32×10⁷−2.00×10⁷ and 2.82×10⁷−4.84×10⁷ dm ³mol⁻¹s⁻¹ for MTBD and TBD respectively. The enthalpies of activation ΔH _MTBD ^≠ =13.5 and ΔH _TBD ^≠ =18.1 kJmol⁻¹. The entropies of activation are negative: ΔS _MTBD ^≠ =−62.3 and ΔS _TBD ^≠ =−40.3 Jmol⁻¹K⁻¹. The change of the absorbance of the anion of 4-nitrophenyl[bis9ethylsulphonyl)]methane at the temperature 25°C in the presence of common cation BH⁺ gives the equilibrium constants K=705 and 906 M⁻¹ for MTBD and TBD respectively. Kinetic and equilibrium results are discussed. The possible mechanism of proton transfer reaction between 4-nitrophenyl[bis(ethylsulphonyl)]methane and cyclic organic bases: MTBD and TBD in acetonitrile is proposed.     

Der Einfluß großer Salzkonzentrationen auf die Oxydationsreaktion von Fe(phen) 3 2+ mit Ce(IV) in Schwefelsäure

The influence of NaClO₄, NaCl and Na₂SO₄ on the oxidation of Fe(phen) ₃ ²⁺ by Ce(IV) was investigated by means of the stopped-flow method. At the concentrations range of NaClO₄ and NaCl 0.1–1.0M the rate constant values decrease from 1.03·10⁵ to 0.56·10⁵M^–1s^–1 and from 1.08·10⁵ to 0.81·10⁵M^–1s^–1 respectively.In varying concentrations of Na₂SO₄ solutions (0.05–0.35M) the rate constant values decrease from 1.05·10⁵M^–1s^–1 to 0.45·10⁵M^–1s^–1.Taking into account the negative salt effect the mechanism of the reaction progress is proposed.

     

Chromium(III) Hydroxide Solubility in The Aqueous Na+-OH?-H2PO?4-HPO2?4-PO3?4-H2O System: A Thermodynamic Model

Chromium(III)-phosphate reactions are expected to be important in managing high-level radioactive wastes stored in tanks at many DOE sites. Extensive studies on the solubility of amorphous Cr(III) solids in a wide range of pH (2.8–14) and phosphate concentrations (10^–4 to 1.0 m) at room temperature (22±2)°C were carried out to obtain reliable thermodynamic data for important Cr(III)-phosphate reactions. A combination of techniques (XRD, XANES, EXAFS, Raman spectroscopy, total chemical composition, and thermodynamic analyses of solubility data) was used to characterize solid and aqueous species. Contrary to the data recently reported in the literature,⁽¹⁾ only a limited number of aqueous species [Cr(OH)₃H₂PO^–₄, Cr(OH)₃(H₂PO₄)^2–₂), and Cr(OH)₃HPO^2–₄] with up to about four orders of magnitude lower values for the formation constants of these species are required to explain Cr(III)-phosphate reactions in a wide range of pH and phosphate concentrations. The log K^o values of reactions involving these species [Cr(OH)₃(aq)+H₂PO^–₄&#x21CC;Cr(OH)₃H₂PO^–₄; Cr(OH)₃(aq)+2H₂PO^–₄&#x21CC;Cr(OH)₃(H₂PO₄)^2–₂; Cr(OH)₃(aq)+HPO^2–₄&#x21CC;Cr(OH)₃HPO^2–₄] were found to be 2.78±0.3, 3.48±0.3, and 1.97±0.3, respectively.     

A kinetic method for <Emphasis Type="Italic">para</Emphasis>-nitrophenol determination based on its inhibitory effect on the catalatic reaction of catalase

The inhibitory effect of para-nitrophenol on the catalytic reaction of catalase was investigated. Michaelis-Menten kinetic parameters were determined from Lineweaver-Burk plots obtained in the absence or in the presence of the inhibitor. The inhibitor pattern, revealed by the Lineweaver-Burk plots, suggested a fully mixed inhibition mechanism. Spectrophotometric monitoring of the indicator reaction: in conjunction with initial rate measurements was employed for the kinetic determination of the inhibitor. Calibration plots of initial rate vs. para-nitrophenol concentration were linear in the concentration range 0.9·10⁻⁵–2.5·10⁻⁵ mol/L and the detection limit was 3·10⁻⁶ mol/L (417 μg/L) para-nitrophenol. Interferences from other phenolic compounds like orto-cresole, meta-and orto-nitrophenol were observed.     

Solvation Structure and Complexation of the Manganese(II) Ion in N,N-Dimethylpropionamide and N,N,N′,N′-Tetramethylurea Studied by Means of Titration Calorimetry and Raman Spectroscopy

Aprotic N,N-dimethylpropionamide (DMPA) and N,N,N′,N′-tetramethylurea (TMU) are both strong donor solvents and coordinate to metal ions through the carbonyl oxygen atom. These solvents show a different conformational aspect in the bulk phase, i.e., DMPA exists as either a planar cis or a nonplanar staggered conformer, while TMU exists in a single planar cis conformer. It has been established that the manganese(II) ion is solvated by five molecules in both solvents. Interestingly, although the planar cis conformer of DMPA is more favorable than the nonplanar staggered one in the bulk phase, the reverse is the case in the coordination sphere of the metal ion, i.e., a conformational change occurs upon solvation. To reveal the thermodynamic aspect of this conformational change, the complexation of Mn(II) with bromide ions in DMPA and TMU has been studied by titration calorimetry at 298 K. It was found that the Mn(II) ion forms mono-, di- and tri-bromo complexes in both solvents, and their formation constants, enthalpies and entropies were obtained. The Δ H∘₁ value for MnBr⁺ strongly depends on the solvent, i.e., it is positive (19.4 kJ-mol⁻¹) in DMPA and negative (−8.7 kJ-mol⁻¹) in TMU, whereas the Δ H^∘₂ and Δ H∘₃ values for the stepwise formation of MnBr₂ and MnBr₃⁻ are both small and negative. The enthalpy of transfer Δ_tH^∘ from DMPA to TMU, which is evaluated on the basis of the extrathermodynamic TATB assumption, is 25.5 kJ-mol⁻¹ for Mn²⁺ and −3.6 kJ-mol⁻¹ for MnBr⁺. These values indicate that the difference between the formation enthalpy of MnBr⁺ in the two solvents, Δ H^∘₁ (DMPA) – Δ H∘₁ (TMU), is mainly ascribed to the value of Δ_tH^∘(Mn²⁺). It is found that the metal ion is also five-coordinated in the monobromo complex, MnBr(DMPA)₄⁺ . The enthalpy for the conformational change of DMPA from its planar cis to the nonplanar staggered form is evaluated to be −11 and −5.5 kJ-mol⁻¹ for Mn(DMPA)₅^{2 +} and MnBr(DMPA)₄⁺, respectively. Note that these values are significantly smaller than the corresponding value (5.0 kJ-mol⁻¹) in the bulk phase. We thus conclude that, although steric hindrance among solvent molecules is reduced by replacing one DMPA of Mn(DMPA)₅^{2 +} with the relatively small bromide ion, DMPA molecules are still sterically hindered in the MnBr(DMPA)₄⁺ complex.     

Molar Excess Volumes and Excess Isentropic Compressibilities of Ternary Mixtures Containing <Emphasis Type="Italic">o</Emphasis>-Toluidine

Molar excess volumes, V _ijk ^E, and speeds of sound, U _ijk , of o-toluidine (i) + benzene (j) + cyclohexane or n-hexane or n-heptane (k) ternary mixtures have been measured as a function of composition at 308.15 K. The observed speed of sound data have been utilized to determine the excess isentropic compressibilities, (K _S ^E) _ijk , of the ternary (i+j+k) mixtures. The Moelywn-Huggins concept (Huggins in Polymer 12: 389–399, 1971) of connectivity between the surfaces of the binary mixture constituents has been extended to ternary mixtures (using the concept of a connectivity parameter of third degree of molecules, ³ ξ, which in turn depends on its topology) to obtain an expression that describes well the measured V _ijk ^E and (K _S ^E) _ijk data. The observed data have also been analyzed in terms of Flory’s theory.