Oxidizing supported reagents, III. Oxidation of alcohols by new supported K2Cr2O7 reagents

Several new supported K₂Cr₂O₇ reagents are used in the oxidation of secondary alcohols. The influence of the number of active sites and the nature of solid support on the yield is discussed. The influence of the structure of alcohol on the yield of ketone is analyzed.

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K₂Cr₂O₇ . . .

     

Importance of the Debye interaction in organic solutions: Henry's law constants for polar liquids in nonpolar solvents and vice versa

Henry's law constants have been determined for -butyrolactone (BL), ethyl acetate (EA), and 2-methyl-3-pentanol (MEP) in mixtures of iso-octane (ISO) and toluene (TOL), for BL, EA, TOL, and ISO in cinnamaldehyde (CIN) and for TOL and ISO in each other and in BL. From these data and published vapor pressures, the activity coefficients at infinite dilution and the standard molar Gibbs free energy of transfer, G ₂ ⁰ of the solutes from dilute solution in ISO to dilute solution in each solvent medium have been calculated. The different behavior patterns of BL and EA are attributed to differences in their abilities to exist in different conformations possessing different dipole moments. For polar solutes, G ₂ ⁰ decreases with increasing polarizability of the solvent and with increasing dipole moment of the solute, suggesting increased contributions from dipole-induced dipole (Debye) interactions. The sigmoidal plot of G ₂ ⁰ against the change in pair potential energy calculated from the classical expressions suggests that G ₂ ⁰ seriously underestimates the strength of the Debye interactions in comparison with the London interactions.     

Examination of the flow behaviour of HEC and hmHEC solutions using structure–property relationships and rheo-optical methods

The effect of solely intermolecular interactions due to hydrophobic alkyl substituents on the flow behaviour of hmHEC solutions was determined via comparison of the structure–property relationships of hmHECs and HECs based on the overlap parameter c[]. For this purpose the ₀–[]–c relationship for HEC was determined to be ₀=8.91·10^–4+8.91·10^–4·c[]+1.07·10^–3(c[])²+1.83·10^–7(c[])^5.56. In addition the structure–property relationship for the longest relaxation time via the –[]–c relationship ·c^1+1/a=2.65·10^–8(c[])²+4.25·10^–8(c[])³+5.44·10^–12(c[])^5.27 has been determined. Although the hmHECs had a higher zero shear viscosity than HECs of comparable overlap parameters at a range of 1<c[]<13, the flow curves could be described via the same –[]–c relationship in that range, indicating a timescale of the intermolecular interactions below the longest relaxation time.The behaviour of the supramolecular structures in solution with an applied shear field was characterized by rheo-optical analysis of the shear thickening behaviour which occurs with addition of surfactant. Contrary to expectations, a slope >1 of the flow birefringence n as a function of shear rate could be observed in double logarithmic plotting. The degree of orientation of the flow birefringence primarily decreases with increasing shear rate, but increases later on at a characteristic shear rate. These two exceptional phenomena can be explained by a pronounced anisotropy of the polymer coils caused by the dilatant flow.This assumption is backed up by the occurrence of a maximum in the dichroism curves which is caused by a finite stability of the aggregated structures in solution. On a molecular basis, these observations agree with the theoretically predicted (Witten and Cohen) transition from intra- to intermolecular polymer micelles. The detected aggregates correspond with the polymer chains that are aligned in one micelle.Abbreviations a Exponent of the Mark–Houwink relationship - c_[]* Critical concentration (determined by intrinsic viscosity) - c_LS* Critical concentration (determined by light scattering) - HASE Hydrophobically modified alkali-swellable emulsions - HEUR Hydrophobically modified ethoxylated urethanes - hmHEC Hydrophobically modified hydroxyethylcellulose - HEC Hydroxyethylcellulose - HPMC Hydroxypropylmethylcellulose - M Molecular mass - MS Molar degree of substitution - n Slope of the flow curve - SEC Size exclusion chromatography - R_G Radius of gyration - Viscosity - ₀ Zero-shear viscosity - _sp Specific viscosity - Longest relaxation time - n Birefringence - n_i Intrinsic birefringence - n_f Form birefringence - n Dichroism - Orientation of the birefringence - ̇ Shear rate     

CoMFA and docking study of novel estrogen receptor subtype selective ligands

We present the results from a Comparative Molecular Field Analysis (CoMFA) and docking study of a diverse set of 36 estrogen receptor ligands whose relative binding affinities (RBA) with respect to 17-Estradiol were available in both isoforms of the nuclear estrogen receptors (ER, ER). Initial CoMFA models exhibited a correlation between the experimental relative binding affinities and the molecular steric and electrostatic fields; ER: r²=0.79, q²=0.44 ER: r²=0.93, q²=0.63. Addition of the solvation energy of the isolated ligand improved the predictive nature of the ER model initially; r²=0.96, q²=0.70 but upon rescrambling of the data-set and reselecting the training set at random, inclusion of the ligand solvation energy was found to have little effect on the predictive nature of the CoMFA models. The ligands were then docked inside the ligand binding domain (LBD) of both ER and ER utilizing the docking program Gold, after-which the program CScore was used to rank the resulting poses. Inclusion of both the Gold and CScore scoring parameters failed to improve the predictive ability of the original CoMFA models. The subtype selectivity expressed as RBA(ER/ER) of the test sets was predicted using the most predictive CoMFA models, as illustrated by the cross-validated r². In each case the most selective ligands were ranked correctly illustrating the utility of this method as a prescreening tool in the development of novel estrogen receptor subtype selective ligands.     

Multi-Syringe Flow Injection System with In-Line Pre-Concentration for the Determination of Total Phenolic Compounds

A multi-syringe flow injection system for the determination of total phenolics based on the 4-aminoantipyrine reaction is proposed. In-line preconcentration using solid-phase extraction was implemented, offering an environmentally friendly alternative to organic solvent extraction performed in the batch procedure and in previously described flow methodologies. Therefore, phenolic compounds were retained in Amberlite XAD4 resin using acidic conditions. The elution was carried out using 0.10molL^–1 NaOH solution, promoting the ionisation of the retained phenolic compounds, and thus their desorption.Since different elution profiles were obtained for several phenol derivatives, the calibration curves were established using the peak area as analytical signal. Moreover, a dynamic calibration range was applied by using a variable sample volume (0.500–6.00mL) and calibration curves based on the mass of phenol retained in the pre-concentration column. A methodology based on a fixed sample volume (24.0mL) was also proposed for determination at concentration levels below 50µgL^–1. A limit of detection of 52ng of phenol (9 or 2µgL^–1) was achieved with a sampling frequency of 10–16h^–1 for the variable volume method and 4h^–1 for the fixed volume method. The application of the proposed methodology to reference material provided results that were within the certified acceptance limits.     

Hydrolysis of Protactinium(V). III. Determination of Standard Thermodynamic Data

Hydrolysis constants of protactinium(V) at tracer scale were deduced from the variations of partition coefficient of Pa(V) in the system: TTA/toluene/Pa(V)/H₂O/H⁺/Na⁺/ClO^– ₄, as a function of TTA and proton concentrations, ionic strength (0.1 3 M), and temperature (10 60°C). Extrapolations of theses constants to zero ionic strength were performed using the SIT model. Standard thermodynamic data (under atmospheric pressure) related to the two hydrolysis equilibria involved, were derived from the temperature dependence of the hydrolysis constants at infinite dilution.     

Kinetics of isotope exchange of dioxygen with a powdered high-temperature superconducting material Ba2YCu3O7?x

It has been found that the rate of isotope exchange in Ba₂YCu₃O_7–x–O₂ system is high. Its kinetics is exponential, first order with respect to dioxygen and the exchange is of the mixed first/third type.

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Ba₂YCu₃O_7–x–O₂ . -, -, - .

     

Influence of pressure reduction on the shapes of thermoanalytical curves of red muds

The effect of reduction of pressure on the shapes of the TG, DTG and DTA curves and the mass-spectra of hydroxide and carbonate phases was investigated in some typical Hungarian red muds. The pressure change caused different decomposition rates of the phases and resulted in better separation of the overlapping thermal curves; this led to advantages as regards phase analysis. For phase analysis the red muds were extracted with water, and the extracts and solid residues were identified by IR- and X-ray methods.

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Zusammenfassung Die Wirkung der Druckänderung auf die Form der TG-, DTG- und DTA-Kurven, sowie der MS-Spektra der Hydroxid- und Carbonatphasen in einigen typischen ungarischen Rotschlamm-Sorten wurde geprüft. Die Druckänderung verursachte verschiedene Zersetzungsgeschwindigkeiten der Phasen, führte zur besseren Auftrennung der sich überlappenden thermischen Kurven, und war ausserdem auch hinsichtlich der Phasenanalyse vom Vorteil. Zur Phasenanalyse wurden die Rotschlämme mit Wasser extrahiert und die Extrakte und festen Rückstände mittels IR- und Röntgenmethoden identifiziert.

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Résumé On a étudié dans quelques espèces typiques de boues rouges de Hongrie l'effet des variations de pression sur la forme des courbes TG, TGD et ATD ainsi que les spectres de masse des phases hydroxyde et carbonate. La variation de la pression entraîne des vitesses de décomposition différentes. Il en résulte une meilleure séparation des phénomènes dans le cas où ceux-ci se chevauchent ainsi que des avantages du point de vue de l'analyse des phases. L'analyse des phases présentes dans les boues rouges a été effectuée par extraction à l'eau. Les extraits et les résidus solides ont été identifiés par spectrométrie infrarouge et par diffraction des rayons X.

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, - . , , . .

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Paper presented at the Scientific Session on Thermal Analysis held at Balatonfüred, Hungary, on 14–16 October 1976.     

Acetylene adsorption on a clean iridium surface

The interaction of C₂H₂ with a polycrystalline iridium surface at 140 KT500 K has been studied by AES, XPS and UPS. A model of the bonding between C₂H₂ and Ir by the 1 orbitals of the hydrocarbon is proposed. The more pronounced energy splitting between the orbitals of acetylene during adsorption compared to that in the gas phase is ascribed to deformation of the acetylene molecule.

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C₂H₂ . 140 KT500 K AES, XPS UPS. C₂H₂ Ir 1- . - , , .

     

Parent and mixed ligand complexes in the copper(II)-ethylene glycol-sulphate system

Eleven copper(II)-ethylene glycol-sulphate complexes of different compositions were prepared, one of them-CuGl₂(H₂O)₂SO₄-in single-crystal form. A thermoanalytical study of these complexes revealed three types of thermal decomposition pattern. The X-ray structure of the single-crystal demonstrated the presence of ethylene glycol bridges resulting in endless chains in the crystal.

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Zusammenfassung Elf Kupfer(II)-äthylenglykol-sulfat-Komplexe unterschiedlicher Zusammensetzung wurden dargestellt, einer davon — CuGl₂(H₂O)₂SO₄ — in Form von Einkristallen. Die thermoanalytische Untersuchung dieser Komplexe ergab drei Typen der thermischen Zersetzung. Die röntgendiffraktometrische Bestimmung der Struktur des in Form von Einkristallen erhaltenen Komplexes zeigte, daß den Kristall endlose Ketten von Äthylenglykolbrücken durchziehen.

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() — , — CuGl₂(H₂O)₂SO₄ — . . , , .

     

A thermal synthesis of a new tin(IV) dithiocarbamate

A new tin dithiocarbamate containing sulphur bridges, di--sulphidobis [bis(N,N-diethyldithiocarbamato)tin(IV)], has been isolated from the thermal decomposition of tetrakis(N,N-diethyldithiocarbamato)tin(IV). A dimeric structure is proposed on the basis of results from mass spectrometry, infrared spectroscopy, thermal analysis and vapour pressure osmometry.

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Zusammenfassung Ein neues, Schwefelbrücken enthaltendes Zinn-Dithiocarbamat, Di--sulfidobis[bis(N,N-diäthyldithiocarbamato)Zinn(IV)], wurde bei der Zersetzung von Tetrakis(N,N-diäthyl-dithiocarbamato)Zinn(IV) isoliert. Aufgrund der Ergebnisse der Massenspektrometrie, der Infrarotspektroskopie, der Thermoanalyse und der Dampfdruck-Osmometrie wird eine Dimerstruktur vorgeschlagen.

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Résumé Un nouveau dithiocarbamate d'étain contenant des ponts de soufre, le di--sulfidobis[bis(N,N-diéthyl-dithiocarbamato)é tain(IV)], a été isolé lors de la décomposition thermique du tétrakis(N,N-diethyl-dithiocarbamato) étain(IV). Une structure dimère est proposéeà partir des résultats obtenus par spectrométrie de masse, spectroscopie infrarouge, analyse thermique et osmométrie sous pression de vapeur.

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—-- [/N,N- (/IV)], [/N,N- (/IV)], , (N,N- ) (IV). - , , .

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The authors gratefully acknowledge the assistance given by Dr. A. G. Wedd with the vacuum sublimation technique. One of us, G. K. B., is grateful for a research scholarship provided by La Trobe University.     

A thermogravimetric study of the solid-state reaction between alumina and strontium carbonate

The kinetics of the solid-state reaction between alumina and strontium carbonate were studied by thermogravimetry. The effects of the structure ( or) and/or doping (with Li⁺ or Cd²⁺) of the alumina on the kinetics of the reaction were examined. The results obtained were correlated with the phase composition and structural changes, followed by a number of physicochemical analyses (DTA, XRA and IRA) throughout the course of the reaction.

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Zusammenfassung Die Kinetik der Festkörperreaktion zwischen Aluminiumoxid und Strontium-carbonat wurde thermogravimetrisch untersucht. Die Effekte der Struktur ( und) und/oder des Dopens des Aluminiumoxids (mit Li⁺ oder Cd²⁺) auf die Kinetik der Reaktion wurde untersucht. Die erhaltenen Ergebnisse wurden mit der Phasenzusammensetzung und mit durch physikalisch-chemische Analysenverfahren (DTA, XRA und IRA) während des Reaktionsverlaufs verfolgten strukturellen Veränderungen in Beziehung gebracht.

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. ( ) Li⁺ Cd²⁺ . , , - .

     

Kinetic laws for dehydrogenation of cyclohexane over Pd/C catalysts

A kinetic equation for cyclohexane dehydrogenation at P_O=1.0 MPa has been obtained.

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1,0 .

     

Radiation induced oxidation of ethyldichlorosilane

It has been revealed that the radiation induced oxidation of ethyldichlorosilane by oxygen produces practically one reaction product, namely chlorine-containing disiloxane. A reaction mechanism involving the formation of silyl hydroperoxide as one of the steps is suggested.

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, — . , .

     

Structure of vanadium phosphate anion in solutions from17O,51V and31P NMR data

¹⁷O,⁵¹V and³¹P NMR studies indicate that the anion structure of sodium vanadophosphate in an aqueous solution is close to that in crystals of the (CN₃H₆)₈HPV₁₄O₄₂ 7H₂O salt.

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¹⁷O,⁵¹V,³¹P , (CN₃H₆)₈HPV₁₄O₄₂ 7H₂O.

     

Thermal analysis of spurrite from a rotary cement kiln

A number of samples from the pre-burning zone of a wet-process cement rotary kiln were examined by combined DTA/TG and XRD for estimation of spurrite (2Ca₂SiO₄·CaCO₃). It was found that decarbonation temperatures of spurrite range from 1130 to 1190 K and they are 45 to 75 K higher than that of calcite occurring in the same sample. In the TG curves calcite and spurrite can be easily distinguished and accordingly both can be estimated from the same TG scan. Combined DTA/TG, supplemented by XRD, is a very effective method for qualitative and quantitative estimation of spurrite in cement rotary kiln materials.

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Zusammenfassung Unter kombinierter Anwendung von DTA/TG und Röntgendiffraktionsverfahren wurde eine Anzahl Proben aus einem Vorkalzinator eines Drehrohrofens zur Zementherstellung nach dem Naßverfahren auf Spurrit (2Ca₂SiO₄·CaCO₃) untersucht. Es wurde festgestellt, daß die Temperatur für das Austreiben von CO₂ bei Spurrit zwischen 1130 und 1190 K und somit um 45–75 °C höher als bei in derselben Probe vorliegenden Kalzit liegt. Aufgrund der TG-Kurven können Kalzit und Spurrit leicht voneinander unterschieden und demzufolge mit einem einzigen TG-Scan bestimmt werden. Kombinierte DTA/TG, ergänzt durch Röntgendiffraktionsverfahren ist eine sehr leistungsstarke Methode zur qualitativen und quantitativen Bestimmung von Spurrit in Stoffen aus Zementdrehrohröfen.

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(2Ca₂SiO₄ · CaCO₃), / , , . , 1130– 1190 , 46–75 , . . /, , .

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The authors are very grateful to Mr. A. H. Dalmia, president, M/s. Orissa Cement Limited, Rajgangpur for allowing to collect the samples during the stoppage of the kiln and also for his permission to publish the paper.     

Radiolysis of nitrous oxide adsorbed on alumina ionic mechanism of radiolysis of nitrous oxide on alumina with small surface areas

A mechanism is proposed for the radiolysis of adsorbed N₂O describing the experimental dependences of the radiation-chemical yields of O _st ^– and N₂ on N₂O coverages.

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N₂O, - O _st ^– N₂ N₂O.

     

The oxidative addition of diphenylphosphine and monophenylphosphine to the electron-rich rhenium-rhenium triple bond. The isolation and characterization of compounds that contain the four-center Re(μ-X)(μ-PR2)Re cluster (X=halide)

Diphenylphosphine oxidatively adds to the ReRe bonds of Re₂ X ₄(-dppm)₂ (X=Cl or Br; dppm=Ph₂PCH₂PPh₂) and Re₂Cl₄(-dpam)₂ (dpam=Ph₂AsCH₂AsPh₂) to afford the dirhenium(III) complexes Re₂(-X)(-PPh₂)HX ₃(-LL)₂. The dppm complexes have also been prepared from the reactions of Re₂(-O₂CCH₃)X ₄(-dppm)₂ with Ph₂PH, and a similar strategy has been used to prepare Re₂(-Cl)(-PPh₂)HCl₃(-dmpm)₂ (dmpm=Me₂PCH₂PMe₂) from Re₂(-O₂CCH₃)Cl₄(dmpm)₂. Phenylphosphine likewise reacts with Re₂ X ₄(-dppm)₂ to give Re₂(-X)(-PHPh)HX ₃(-dppm)₂. An X-ray crystal structure determination on Re₂(-Cl)(-PPh₂)HCl₃(-dppm)₂ confirms its edge-shared bioctahedral structure. This complex crystallizes in the space group (No. 148) witha=21.699(3) Å, =84.50(4)°,V=10084(5) ų, andZ=6. The structure was refined toR=0.049 (R _w 0.069) for 5770 data withI>3.0(I). The Re-Re distance is 2.5918(7) Å. Oxidation of the bromide complex Re₂(-Br)(-PPh₂)HBr₃(-dppm)₂ with NOPF₆ produces the unusual dirhenium(III, II) cation [Re₂(-H)(-Br)[P(O)Ph₂]Br₂(NO)(-dppm)₂]⁺ which has been structurally characterized as its perrhenate salt, [Re₂(-H)(-Br)[P(O)Ph₂]Br₂(NO)(-dppm)₂]ReO₄ · 2CH₂Cl₂. This complex crystallizes in the space group (No. 2) witha=14.187(7) Å,b=16.419(5) Å,c=16.729(5) Å, =98.76(2)°, =110.11(3)°, =104.66(3)°,V=3414(6) ų,Z=2. The structure was refined toR=0.040 (R _w =0.051) for 5736 data withI>3.0(I). The presence of a phosphorus-bound [P(O)Ph₂]^– ligand, a linear nitrosyl and a bridging hydrido ligand has been confirmed. The Re-Re distance is 2.6273(8) Å.     

Thermal decomposition of the solvent-extracted chloro complexes of vanadium(IV) with trioctylamine and trioctylmethylammonium chloride

The complexes (R₃NHVO(OH)Cl₂)₂ and (R₃RNVO(OH)Cl₂)₂ prepared by drying in vacuo the organic solutions from the extraction into benzene of aqueous vanadyl chloride solution with trioctylamine (TOA, R₃N) and trioctylmethylammonium chloride (TOMAC, R₃RNCl), were studied by thermogravimetry and differential thermal analysis under an atmosphere of nitrogen, and the products of their thermal decomposition, such as volatile matter and residues, by gas chromatography. X-ray diffraction and infrared spectroscopy. It was found that the complexes with TOA and TOMAC thermally decompose to V₂O₃ at 200–300° by cracking of the compounds R₃NHVO(OH)Cl₂ and R₃RNVO(OH)Cl₂ formed via dissociation of the complexes at about 150°.

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Zusammenfassung Die Komplexe (R₃NHVO(OH)Cl₂)₂ und (R₃RNVO(OH)Cl₂)₂ wurden hergestellt, indem benzolische und wässrige Vanadylchlorid-Lösungen mit Trioctylamin (TOA, R₃N) und Trioctylmethylammoniumchlorid (TOMAC, R₃RNCl) extrahiert und die erhaltenen Lösungen im Vakuum eingedampft wurden. Die Komplexen wurden in Stickstoffatmosphäre mittels TG und DTA untersucht und die thermischen Zersetzungsprodukte, und zwar sowohl die flüchtigen Verbindungen als auch die Rückstände, gaschromatographisch bzw. röntgendiffraktometrisch und IR-spektroskopisch bestimmt. Es wurde festgestellt, daß die Komplexe mit TOA und TOMAC bei 150° in die Verbindungen R₃NHVO(OH)Cl₂ und R₃RNVO(OH)Cl₂ dissoziieren, die bei 200–300° thermisch zu V₂O₃ zersetzt werden.

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(R₃NHVO(OH)Cl₂)₂ (R₃RNVO(OH)Cl₂)₂ (R₃,) ( , R₃RNCl). , , . , 200–300° V₂₃ R₃NV()l₂ R₃RNVO(OH)Cl₂, 150°.

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We wish to thank the Koei Chemical Co. Ltd. for samples of TOA and TOMAC.