Thermodynamics of the isopropanol/n-hexane and isopropanol/n-heptane systems. Part III. Gas/liquid equilibrium

Vapour pressure measurements are carried out at different temperatures; the activity coefficients are calculated and compared with those devived from IR and NMR data (parts I and II).

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Zur Thermodynamik des Isopropanol/n-Hexan und Isopropanol/n-Heptan Systems, III. Gas-Flüssig-Gleichgewichte

Zusammenfassung Es wurden Dampfdruckmessungen bei verschiedenen Temperaturen ausgeführt. Die daraus bestimmten Aktivitätskoeffizienten wurden mit den aus IR- und NMR-Daten berechneten (siehe Mitt. I und II) verglichen.

     

Thermodynamics of the isopropanol/n-hexane and isopropanol/n-heptane systems. Part I. Infrared studies

The association equilibria for different conglomerates are calculated for the isopropanol/n-Hexane, isopropanol/n-Heptane systems from the infrared spectra.

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Zur Thermodynamik des Isopropanol/n-Hexan und Isopropanol/n-Heptan Systems, I. Untersuchungen mittels IR-Spektroskopie

Zusammenfassung Es werden die Assoziationsgleichgewichte für verschiedene Konglomerate im Isopropanol/n-Hexan- bzw.-/n-Heptan-System aus den IR-Spektren abgeleitet.

     

Spectrophotometric study of the reaction of Co(II) and Ni(II) with nitroso-R-salt and α-nitroso-β-naphthol

The complexes of Co(II) and Ni(II) with nitroso-R-salt are studied by conductometric titration and spectrophotometric methods in buffer solutions of differentpH. The study proved the possible formation of (11), (12) and (13) complexes for Co(II) while Ni(II) forms (11) and (12) complexes (metal:ligand) only. The factors affecting complex formation are established and the formation constants of the complexes are evaluated. The ir spectra of the solid complexes with -nitroso--naphthol revealed that the ligand exhibits the nitrosophenol structure and that the reaction takes place through proton displacement from the OH-group.

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Spektrophotometrische Studie zur Reaktion von Co(II) und Ni(II) mit Nitroso-R-Salz und -Nitroso--naphthol

Zusammenfassung Es wurden die Komplexe von Co(II) und Ni(II) mit Nitroso-R-Salz mittels konduktometrischer und spektrophotometrischer Methoden in Puffer-Lösungen mit verschiedenempH untersucht. Für Co(II) wurden (11)-, (12)- und (13)-Komplexe gefunden, während für Ni(II) lediglich (11)- und (12)-Komplexe (Metall:Ligand) festgestellt werden konnten. Die Faktoren, die die Komplexierung bestimmen, werden diskutiert und die Komplexbildungskonstanten wurden bestimmt. Die IR-Spektren der Komplexe mit -Nitroso--naphthol zeigen, daß der Ligand in der Nitrosophenol-Form vorliegt und daß die Reaktion über eine Protonenverschiebung von der OH-Gruppe verläuft.

     

13C NMR of indazoles

The carbon-13 chemical shifts and some selected coupling constants of 183 indazoles are reported. The main conclusions of the original references are briefly summarized.Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1159–1179, September, 1995.     

Volume properties of solutions of oleic, linoleic, and linolenic acids in n-hexane and n-heptane at 298.15 K

Densities of solutions of oleic, linoleic, and linolenic acids in n-hexane and n-heptane were measured using a vibrating-tube densimeter at 298.15 K in a concentration range of 0–0.012 molar fractions of solute. The measurement error does not exceed ±5·10⁻⁶ g cm⁻³. The limiting partial molar volumes of fatty acids of the studied series in n-hexane and n-heptane and the excess volume properties of binary mixtures were calculated. On going from oleic to linolenic acid, the number of double bonds (>C=C<) in a solute molecule increases, the hydrocarbon chain length in a solvent molecule decreases, and compactness of the structure packing of the resulting solution increases. This is caused, as a whole, by the enhancement of the n-alkane—acid intermolecular interaction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 643–647, April, 2006.     

Thermodynamics and phase equilibrium studies of silver halide-cobalt(II) halide systems

Phase diagrams for the systems AgCl-CoCl₂ and AgBr-CoBr₂ were determined by differential scanning calorimetry. The systems are of the eutectic type. Eutectic points are at 271±2 K, 19.5 mol% CoCl₂ and 653±2 K, 17.0 mol% CoBr₂, respectively. The solid solubility does not exceed 2 and 4 mol% in the systems AgCl-CoCl₂ and AgBr-CoBr₂, respectively. Thermodynamic activities of components in molten mixtures and molar free enthalpies of mixing were determined for both systems on the basis of liquidus curves. Deviations from ideality were not found to be considerable.     

Potentiometric studies on the complex formation of lanthanides with proline and hydroxyproline

The formation of the lanthanide (La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) complexes with proline and hydroxyproline has been investigated by potentiometric methods as well as by a turbidimetric one which has provided some additional conclusions. It has been found that 11 and a slight amount of 21 complexes are formed. The deviation from the typical course of the formation function is discussed. It is suggested that the perturbations of complex formation in the systems are caused by hydrolysis. The stability constants of the complexes are reported.

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Potentiometrische Untersuchungen an Lanthanid-Komplexen von Prolin und Hydroxyprolin

Zusammenfassung Die Bildung von Lanthanid-Komplexen (La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) mit Prolin und Hydroxyprolin wurde potentiometrisch und mit Hilfe von Trübungsmessungen untersucht. Es wurde festgestellt, daß sich Komplexe der Zusammensetzung 11 und in kleiner Menge auch 21 bilden. Die Abweichung von typischem Verlauf der Bildungskurven wurde untersucht. Es wurde dabei festgestellt, daß für die Störungen in der Komplexbildung die Hydrolyse verantwortlich ist. Die Stabilitätskonstanten wurden bestimmt.

     

Solid-state C NMR and molecular modeling studies of acetyl aleuritolic acid obtained from Croton cajucara Benth

Solid-state ¹³C nuclear magnetic resonance (¹³C NMR) with magic-angle spinning (MAS) and with cross-polarization and magic-angle spinning (CP/MAS) spectra, and differential scanning calorimetry (DSC) techniques were used to obtain structural data from a sample of acetyl aleuritolic acid (AAA) extracted from the stem bark of Croton cajucara Benth. (Euphorbiaceae) and recrystallized from acetone. Since solid-state ¹³C NMR results suggested the presence of more than one molecule in the unitary cell for the AAA, DSC analysis and molecular modeling calculations were used to access this possibility. The absence of phase transition peaks in the DSC spectra and the dimeric models of AAA simulated using the semi-empirical PM3 method are in agreement with that proposal.     

Dielectric studies of molecular complexes ofDDT with some compounds of biological interest

The molecular complexation ofDDT (acceptor) with some compounds of biological interest as donors (e.g. indole, 2-methylindole, 3-methylindole, benzene and naphthalene) have been studied using refractive index,Guggenheim and dielectric titration plot methods. The interaction between these donors with solvents (CCl₄ and C₆H₆) have also been observed by calculating _ind through _ind=_sol–_inert. These data have shown that the molecular interaction between polar solutes and non-polar aromatics is governed by dipole-induced dipole electrostatic attraction. The dipole moment obtained due to charge transfer (_DA) has also been calculated and found that its value increases with the increase in the extent of interaction between donor and acceptor. These data support the charge-transfer complex formation hypothesis for the mode of action ofDDT on molecular level.

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Dielektrizitäts-Untersuchungen an Molekülkomplexen von DDT mit einigen biologisch relevanten Verbindungen

Zusammenfassung Es wurden Molekülkomplexe vonDDT (als Acceptor) mit einigen Verbindungen von biologischem Interesse (als Donoren: Indol, 2-Methyl-indol, 3-Methyl-indol, Benzol und Naphthalin) mittels Brechungsindex,Guggenheim-Methode und dielektrischer Titration untersucht. Dipolmomentberechnungen ergaben, daß die intermolekulare Wechselwirkung von einer Anziehung induzierter Dipol-Dipol bestimmt wird; es wurde auch der charge-transfer-Anteil des Dipolmoments abgeschätzt. Alle diese Daten unterstützen die Annahme der charge-transfer-Komplexierung vonDDT.

     

Refractometric studies of molecular complexes ofDDT with some compounds of biological interest

Formation of molecular complexes betweenDDT as acceptor and indole, 2-methylindole, 3-methylindole, benzene and naphthalene as donors have been studied in carbon tetrachloride using refractometric and differential refractometric measurements. Titration techniques through these measurements have indicated11 stoichiometry of these complexes. Equilibrium constants (K ₁) and extent of electronic polarization were calculated. Two types of complexes were observed, one association involving primarily the benzhydryltrichloromethyl grouping ofDDT with a polar complexing agents, and the other interaction of theDDT aromatic -electron system with -electrons of donors in the complexing molecule. These data support the charge-transfer complex formation hypothesis for the mode of action ofDDT on molecular level.

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Refraktometrische Untersuchungen an Molekülkomplexen von DDT mit einigen biologisch relevanten Verbindungen

Zusammenfassung Es wurde die Bildung von Molekülkomplexen zwischenDDT als Acceptor und Indol, 2-Methyl-indol, 3-Methyl-indol, Benzol und Naphthalin als Donor in CCl₄ mittels Refraktometrie und differenzieller Refraktometrie untersucht. Es wurde11-Stöchiometrie der Komplexe festgestellt, Gleichgewichtskonstanten und das Ausmaß der Elektronenpolarisation wurden berechnet. Zwei Typen von Komplexen wurden beobachtet; in einem Fall erfolgt die Assoziation primär über die Benzhydryltrichlormethyl-Gruppierung desDDT, im anderen Fall über -Elektronenwechselwirkungen. Die Daten unterstützen ein chargetransfer-Modell der Komplexbildung vonDDT mit geeigneten Donormolekülen.

     

Small angle neutron scattering studies on micellar systems part 2. Mixed systems of ammonium decanoate and ammonium perfluoro-octanoate

Mixtures of ammonium decanoate (AmDec) and ammonium perfluoro-octanoate (APFO), in ammonium chloride: ammonium hydroxide buffer at pH 8.8 and an ionic strength of 0.1, were examined by small angle neutron scattering with varying proportions of the two surface active agents. The results indicated that mixed micelles were formed and it is suggested from analysis of the data that these were cylindrical in shape at APFO: AmDec ratios of 21, 11 and 12. At 21 and 11 the micelles were found to contain more APFO than expected on the basis of ideal mixing of the surface active agents in the micelle. At a ratio of 19 the micelles were found to be spherical but larger than those formed from AmDec alone. A speculative model is proposed for the mixed micelle which still, however, allows for segregation between hydrocarbon and fluorocarbon chains within the micelle.     

Synthesis and structural studies of Co(II) and Ni(II) complexes of glutaric- and adipic dihydrazides

Glutaric dihydrazide (GDH) and adipic dihydrazide (ADH) have been found to react with Co(II) chloride and Ni(II) chloride and nitrate in ethanolic solution to form complexes of the general empirical compositionsMLCl₂,ML ₂Cl₂ and [NiL ₂(H₂O)₂] (NO₃)₂ whereM=Co(II), Ni(II) andL=GDH,ADH. Tetrahedral geometry has been proposed for 11 complexes of Co(II) and octahedral geometry for the remaining complexes based on measurements of molar conductance, magnetic susceptibility, electronic and ir spectra.

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Synthese und Struktur von Co(II)- und Ni(II)-Komplexen von Glutarsäure- und Adipinsäuredihydraziden

Zusammenfassung Glutarsäuredihydrazid (GDH) und Adipinsäuredihydrazid (ADH) bilden mit Co(II)-Chlorid und Ni(II)-Chlorid bzw.-Nitrat in ethanolischer Lösung Komplexe der generellen ZusammensetzungenMLCl₂,ML ₂Cl₂ und [NiL(H₂O)₂] (NO₃)₂, mitM=Co(II), Ni(II) undL=GDH,ADH. Für 11-Komplexe von Co(II) wird eine tetragonale Geometrie, für alle anderen Komplexe eine oktaedrische Geometrie vorgeschlagen. Die Basis dazu lieferten Messungen der molaren Leitfähigkeit, der magnetischen Suszeptibilität und der UV- bzw. IR-Spektren.

     

Quantitative 2H NMR spectroscopy. 1. Thermodynamic H/D isotope effects in N,N-dimethylformamide and cyclopentadiene molecules

A new method for quantification of the relative distribution of deuterium in molecules is proposed. The technique is based on the lineshape analysis in the ²H NMR spectra obtained at the natural abundance level of deuterium with allowance for inhomogeneity of the magnetic field. The equilibrium thermodynamic H/D isotope effects for hindered rotation about the C—N bond in the N,N-dimethylformamide molecule and for prototropic exchange in the cyclopentadiene molecule were determined. The results obtained agree with those of DFT calculations of the vibrational energies.     

Structure elucidation with lanthanide-induced shifts 5. Evaluation of the binding ability of various functional groups

The equilibrium binding constants have been evaluated for the association in CCl₄ of the lanthanide shift reagent. Eu(fod)₃, with a series of adamantane derivatives containing a variety of different functional groups. It is shown that if steric effects are held constant the binding abilities of the adamantane derivatives exhibit a good correlation with the proton affinities of the methyl analogs containing the same functional groups. The results permit the prediction of binding strength of other functional groups with Eu(dpm)₃ as well as with Eu(fod)₃ and thus can be of great assistance in planning and interpreting the results of experiments with lanthanide shift reagents.Part 4:D. J. Raber, M. D. Johnston, jr., C. M. Campbell, C. M. Janks, andP. Sutton, Org. Mag. Res.11, 323 (1978).     

Synthesis and physico-chemical studies of some polynuclear mixed carboxylate complexes of nickel(II)

A number of polynuclear mixed carboxylates of nickel(II) with the general composition [Ni(OOCCH₃)_2–n (OOCR) _n ] _x (whereR=C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅ and C₂₁H₄₃ andn=1 or 2) have been synthesized by the transacylation reactions of anhydrous nickel acetate with higher carboxylic acids in refluxing toluene. On recrystallization from benzene-alcohol mixtures, mono-alcoholate complexes, Ni(OOCCH₃)_2–n (OOCR) _n ·ROH (whereR=CH₃ and C₂H₅) have been isolated. All these derivatives have been characterized by the molecular weight determinations, infra-red and electronic reflectance spectra and magnetic susceptibility measurements.

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Synthese und Eigenschaften einiger gemischter Carboxylat-Komplexe von Nickel(II)

Zusammenfassung Komplexe des Typs [Ni(OOCCH₃)_2–n (OOCR) _n ] _x (mitR=C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅ und C₂₁H₄₃,n=1 oder 2) wurden aus wasserfreiem Nickelacetat mit höheren Carbonsäuren in siedendem Toluol erhalten. Bei der Kristallisation aus Benzol-Alkohol-Mischungen wurden Monoalkoholate Ni(OOCCH₃)_2–n (OOCR) _n ·ROH (mitR=CH₃ und C₂H₅) isoliert. Die Charakterisierung der Komplexe erfolgte mittels Molekulargewichtsbestimmung, Infrarot- und Elektronenspektren und der Messung der magnetischen Susceptibilität.

     

Small-angle X-ray scattering studies on the X-ray induced aggregation of malate synthase I. Structural and kinetic studies

Small-angle X-ray scattering measurements on malate synthase in aqueous solution revealed a continuous increase of the intensity in the innermost portion of the scattering curve with increasing measuring time. We have definite evidence that this increase reflects an X-ray induced aggregation of the enzyme particles in the course of the small-angle X-ray scattering experiment. Obviously this aggregation is a consequence of a radiation damage of the particles by the primary beam used in the scattering experiment.The aggregation process of malate synthase was monitoredin situ by smallangle X-ray scattering. For this purpose scattering curves were taken at various stages of aggregation. The analysis of these curves established the increase of the particle dimensions, the retention of the pseudo thickness factor of the native enzyme and the occurrence of one and later on of two pseudo cross-section factors. These results suggest the way how the aggregation might proceed. The results led to a tentative model of the aggregation process in which a one-dimensional side-by-side association of the oblate enzyme particles is followed by a two-dimensional aggregation. An aggregation in the third dimension was not observed during the time covered by our experiment.The time dependence of molecular parameters, for instance of the apparent mean radius of gyration, was used to compare the aggregation of enzyme samples that were irradiated under different experimental conditions. The addition of dithiothreitol to the enzyme solutions as well as the presence of the substrates or of a substrate analogue or of ethanol were found to reduce the rate of aggregation.

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Röntgenkleinwinkeluntersuchungen der durch Röntgenstrahlen induzierten Aggregation der Malatsynthase. I. Strukturuntersuchungen und kinetische Messungen

Zusammenfassung Röntgenkleinwinkeluntersuchungen an wäßrigen Lösungen von Malatsynthase zeigten eine mit der Meßdauer ansteigende Zunahme der Streuintensität im Innenteil der Streukurve. Dieser Intensitätsanstieg spiegelt zweifelsohne eine durch die Röntgenbestrahlung induzierte Aggregation der Enzymteilchen während der Röntgenkleinwinkelmessung wider. Diese Aggregation ist offensichtlich auf einen durch die Primärstrahlung verursachten Strahlenschaden zurückzuführen.Das Fortschreiten der Aggregation der Malatsynthase wurde mit Hilfe der Röntgenkleinwinkelstreuungin situ verfolgt. Zu diesem Zweck wurden Streukurven bei verschiedenen Aggregationsstadien aufgenommen. Die Analyse dieser Kurven zeigte die Zunahme der Teilchendimensionen, das Beibehalten des Pseudodickenfaktors des nativen Enzyms und das Auftreten eines und später zweier Pseudoquerschnittsfaktoren an. Diese Ergebnisse lieferten Hinweise, wie die Aggregation ablaufen könnte, und führten zu einem möglichen Modell für den Aggregationsvorgang. Demnach sollte auf eine eindimensionale, laterale Aggregation der oblaten Enzymteilchen eine zweidimensionale Aggregation folgen. Ein Fortschreiten der Aggregation in der dritten Dimension konnte während der Dauer des Experimentes nicht beobachtet werden.Die zeitliche Abhängigkeit molekularer Parameter, z. B. des apparenten mittleren Streumassenradius, wurde für den Vergleich der Aggregation von Enzymproben, die unter verschiedenen experimentellen Bedingungen bestrahlt wurden, herangezogen. Durch Zugabe von Dithiothreitol oder Ethanol zu den Enzymlösungen oder durch die Anwesenheit der Substrate oder eines Substratanalogen konnte die Aggregationsgeschwindigkeit herabgesetzt werden.

     

Dielectric and13C NMR studies of sulfur dioxide-hydroquinone clathrates

Dielectric measurements of SO₂ quinol clathrates show that the reorientation of encaged SO₂ molecules is very rapid and depends greatly on the degree of cage occupancy. For a-quinol sample of cage occupancy = 0.57, the reorientation rate was 1 MHz at 6 K, with a reorientational activation energy of 673 J/mol. For a sample identified by¹³C NMR as-quinol, and for a-quinol sample with most cages filled with Xe, SO₂ reorientation rates are even greater, with activation energies of only some tens of J/mol. The low temperature dielectric studies show that some ethanol may be enclathrated in-quinol recrystallized from this solvent. The¹³C NMR spectra confirm the X-ray results that the lattice becomes distorted with increased SO₂ content.Dedicated to Dr D. W. Davidson in honor of his great contributions to the sciences of inclusion phenomena.     

Mercury(II) cyanide complexes with alkyldiamines: solid-state/solution NMR,computational, and antimicrobial studies

Mercury cyanide complexes of alkyldiamines (1–6), [Hg(L)(CN)₂] (where L?=?en (1,2-diaminoethane), pn (1,3-diaminopropane), N-Me-en, N, N′-Me₂-en, N, N′-Et₂-en, and N, N′-ipr₂-en), have been synthesized and characterized by elemental analysis, IR, ¹³C, and ¹⁵N solution NMR in DMSO-d₆, as well as ¹³C, ¹⁵N, and ¹⁹⁹Hg solid-state NMR spectroscopy. Complexes 1 and 2 have been studied computationally, built and optimized by GAUSSIAN03 using DFT at B3LYP level with LanL2DZ basis set. Binding modes of en and bn (where bn?=?1,4-diaminobutane) toward Hg(CN)₂ are completely different. Complexes with en and pn show chelating binding to Hg(II), while bn behaves as a bridging ligand to form a polymeric structure, [Hg(CN)₂-bn]_∞ [B.A. Al-Maythalony, M. Fettouhi, M.I.M. Wazeer, A.A. Isab. Inorg. Chem. Commun., 12, 540 (2009).]. The solution ¹³C NMR of the complexes demonstrates a slight shift of the ?C≡N (0.9 to 2?ppm) and ?C–NH₂ (0.25 to 6?ppm) carbon resonances, while the other resonances are relatively unaffected. ¹⁵N labeling studies have shown involvement of alkyldiamine ligands in coordination to the metal. The principal components of the ¹³C, ¹⁵N, and ¹⁹⁹Hg shielding tensors have been determined from solid-state NMR data. Antimicrobial activity studies show that the complexes exhibit higher antibacterial activities toward various microorganisms than Hg(CN)₂.     

Dehydrogenation studies of dihydronicotinamide adenine dinucleotide (NADH) with methylene blue in the presence of the copper hexcyanoferrate(II) complex and light

The effects of copper ferrocyanide and light on the dehydrogenation rate of NADH by methylene blue is studied. The results suggest that the dehydrogenation rate of NADH with methylene blue is enhanced by copper ferrocyanide. Light also affects the reaction rate.     

NMR studies of 4(3H)-quinazolinones and 4(3H)-quinazolinethiones

Summary Unambiguous¹H and¹³C NMR assignments for 4(3H)-quinazolinones1–6 and their corresponding 4-thiones7–12 have been made. This resulted in the revision of the previous assignments for the two benzenoid carbons (C-5 and C-8) of quinazolinones1,2,4, and5. Thionation of the nucleophilic amides1–6 has been found to cause a distinct change in the¹³C chemical shift of particularly C-4, but also of those of C-4a, C-5, and C-8a. One-bond and several long range heteronuclear coupling constants for the compounds have also been measured.

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Kernresonanzspektroskopie von 4(3H)-Chinazolinonen und 4(3H)-Chinazolinthionen

Zusammenfassung Die¹H- und¹³C-NMR-Spektren der 4(3H)-Chinazolinone1–6 und ihrer entsprechenden 4-Thione7–12 wurden zugeordnet. Dabei zeigte sich, daß eine frühere Zuordnung der beiden benzoiden Kohlenstoffe (C-5 und C-8) der Chinazolinone1,2,4 und5 falsch war. Ersatz des Sauerstoffs durch Schwefel in den nukleophilen Amiden1–6 führt insbesondere für C-4, aber auch für C-4a, C-5 und C-8a zu einer deutlichen Änderung der chemischen Verschiebung. Heteronukleare Kopplungskonstanten über eine und über mehrere Bindungen wurden bestimmt.