Ultrasonic measurements and other allied parameters of yttrium soaps in mixed organic solvents

The ultrasonic measurements of yttrium soaps were made in a mixture of 70% benzene and 30% dimethylsulfoxide (v/v) to determine the critical micelle concentration, soap-solvent interaction and various acoustic and thermodynamic parameters. The values of the CMC decrease with increasing chainlength of fatty acid constituent of the soap molecule and are in agreement with the values obtained from other micellar properties. The various acoustic parameters (intermolecular free-length, adiabatic compressibility, apparent molar compressibility, specific acoustic impedance, apparent molar volume, molar sound velocity, solvation number, available volume and relative association) for yttrium soaps (myristate, palmitate, stearate and oleate) have been evaluated by ultrasonic velocity measurements.

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Ultraschallmessungen und damit verknüpfte Parameter von Yttrium-Seifen in gemischten organischen Lösungsmitteln

Zusammenfassung Es wurden Ultraschallmessungen von Yttrium-Seifen in einer Mischung 70% Benzol und 30% Dimethylsulfoxid (v/v) durchgeführt, um die kritische Micellenkonzentration, Seifen-Solvens-Wechselwirkung und verschiedene akustische und thermodynamische Parameter zu bestimmen. Die CMC-Werte fallen mit steigender Kettenlänge der Fettsäurekomponente des Seifenmoleküls und sind damit in Übereinstimmung mit den aus anderen micellaren Eigenschaften bestimmten Werten. Verschiedene akustische Parameter (intermolekulare freie Länge, adiabatische Kompressibilität, effektive molare Kompressibilität, spezifische akkustische Impedanz, effektives molares Volumen, molare Schallgeschwindigkeit, Solvatationszahl, verfügbares Volumen und relative Assoziation) der Yttrium-Seifen (Myristat, Palmitat, Stearat und Oleat) wurden aus den Ultraschallmessungen ermittelt.

     

Ultrasonic and viscosimetric studies of samarium laurate in benzene-dimethylsulfoxide mixtures

Summary Ultrasonic and viscosity measurements of samarium laurate in benzene-DMSO mixtures of different compositions (7:3 and 1:1 V/V) have been used to determine the critical micelle concentration (CMC), soap-solvent interaction, and various acoustic parameters of the system. The values of critical micelle concentration increase with increasing amount ofDMSO in the solvent mixtures. The viscosity results have been explained on the basis of equations proposed byEinstein,Vand. Moulik, andJones-Dole. The values of CMC for samarium laurate obtained from the viscosity measurements are in agreement with the results obtained from ultrasonic measurements. The results show that the soap molecules do not aggregate appreciably below CMC; there is a marked change in the aggregation behaviour at CMC.

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Ultraschall- und Viskositätsmessungen an Samariumlaurat in Benzol-DMSO-Mischungen

Zusammenfassung Mit Hilfe von Ultraschall- und Viskositätsmessungen an Samariumlaurat in Benzol-DMSO — Mischungen verschiedener Zusammensetzung (7:3 und 1:1 v/v) wurden die kritische Micellenkonzentration (CMC), Seife-Lösungsmittel-Wechselwirkungen und verschiedene akustische Parameter des Systems bestimmt. Die Werte für die kritische Micellenkonzentration steigen mit wachsendem Anteil vonDMSO im Lösungsmittelgemisch. Die Érgebnisse der Viskositätsmessungen werden auf der Basis der Gleichungen vonEinstein,Vand,Moulik undJones-Dole erklärt. Die CMC-Werte für Samariumlaurat aus Viskositäts- und Ultraschallmessungen stimmen überein. Die Ergebnisse zeigen, daß die Seifenmoleküle bei Konzentrationen unter CMC nicht stark aggregieren; bei Erreichen des CMC-Werts tritt eine ausgeprägte Änderung im Aggregationsverhalten ein.

     

Ultrasonic measurements on the solutions of lanthanum and cerium soaps in non-aqueous medium

The ultrasonic velocity and density measurements of lanthanum and cerium soaps in a mixture of 60 % benzene and 40 % methanol (v/v) were used to evaluate various acoustic and thermodynamic parameters and to determine the CMC. The results were interpreted in terms of soap-solvent interaction.     

Hydration of alcohols by ultrasonic velocity measurements in ternary systems

Ultrasonic velocity maxima have been determined as a function of alcohol (methanol, ethanol, n-propanol or t-butanol) concentration in ternary aqueous alcoholic solutions of a number of mono- and polyhydroxyalcohols. The location of the maxima relative to those in the binary water-alcohol systems are related to the hydration of the solute molecule. It is established that correlations between the extent of hydration and some structural parameters of the solute molecules are of the same character in all binary solvents studied.     

Temperature dependent ultrasonic and conductivity studies in aqueous polymeric solution

Sound velocities, viscosity and density of aqueous solution of PEG of average molecular weight of 4000 g/mole have been measured as a function of temperature in the range 308–338 K at different frequencies. Isentropic compressibility, ultrasonic attenuation and acoustic impedance have been derived from the data. From velocity measurements it has been found that velocity changes near melting temperature due to change in the lattice of polymer. Changes in polymer lattice can also be monitored by complex impedance spectroscopy hence, real and imaginary part of the impedance of mixture of PEG with water were measured in the frequency range 40 Hz to 100 kHz in the same temperature range. From these data bulk electrical conductivity has been calculated. The results have been discussed in terms of molecular interaction occuring in the solution.     

Studies on molar volume and rheology of terbium soaps in a benzene-DMF mixture

Summary Molar volume (V), apparent molar volume (_v), and fluidity () of terbium soaps in benzene-DMF (7:3 v/v) were evaluated at constant temperature from density and viscosity measurements. The results were used to determine the critical micelle concentration (CMC), soap-solvent and soap-soap interactions, and the effect of the chain length of soap molecules on various parameters. The molar volume and viscosity results are discussed in terms of known relations.

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Untersuchungen zum Molvolumen und zur Rheologie von Terbiumseifen in Benzol-DMF

Zusammenfassung Molvolumen (V), scheinbares Molvolumen (_v) und Fluidität () von Terbiumseifen in einer Mischung aus Benzol undDMF (7:3 v/v) wurden bei konstanter Temperatur aus Dichte-und Viskositätsmessungen ermittelt. Aus den Ergebnissen wurden die kritische Micellenkonzentration (CMC), Seifen-Lösungsmittel- und Seifen-Seifen-Wechselwirkungen sowie der Effekt der Kettenlänge der Seifenmoleküle auf verschiedene Parameter bestimmt. Die Resultate bezüglich Molvolumen und Viskosität werden anhand bekannter Beziehungen diskutiert.

     

Physico-chemical studies on samarium soaps in solid state

Summary The physico-chemical characteristics of samarium soaps (caproate and caprate) in solid state were investigated by IR, X-ray diffraction and TGA measurements. The IR results revealed that the fatty acids exist in dimeric state through hydrogen bonding and samarium soaps possess partial ionic character. The X-ray diffraction measurements were used to calculate the long spacings and the results confirmed the double layer structure of samarium soaps. The decomposition reaction was found kinetically of zero order and the values of energy of activation for the decomposition process for caproate and caprate were found to be 8.0 and 7.8 kcal mol^–1, respectively.

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Physikochemische Untersuchungen an Samariumseifen in festem Zustand

Zusammenfassung Die physikochemischen Charakteristika von Samariumseifen (Caproat und Caprat) wurden im festen Zustand mittels IR, Röntgendiffraktion und TGA-Messungen untersucht. Die IR-Ergebnisse zeigten, daß die Fettsäuren durch Wasserstoffbrücken dimer vorliegen und daß die Samariumseifen partiell ionischen Charakter besitzen. Die Röntgenuntersuchungen bestätigen die Doppelschichtstruktur der Seifen. Die Zersetzungsreaktion verlief nach nullter Ordnung, und die Aktivierungsenergien für den Zersetzungsprozeß für Caproat und Caprat waren 8.0 und 7.8 kcal mol^–1.

     

Analysis of ultrasonic velocity in refrigerants using artificial neural network

Several researchers have reported numerous measurements on ultrasonic velocity as a function of temperature and pressure using various experimental techniques. A large amount of experimental data is required in order to obtain accurate results for the chemical substances used. The present article explores the evaluation of ultrasonic velocity as a function of molecular weight, temperature and pressure using an artificial neural network (ANN) in six refrigerants. The network so developed predicts the ultrasonic velocity successfully. Statistical analysis of the results was performed using standard deviation (%) and relative average deviation. The correlation coefficient in our analysis was found to be 0.9999. The trained weights, obtained from ANN, are further employed to form equations to predict ultrasonic velocity at other temperatures and pressures.     

Application of samarium reagents in organic synthesis

Application of samarium diiodide, samarium triiodide, Sm0/auxiliary system and organosamarium reagents in organic synthesis was reviewed.     

Ultrasonic velocity and absorption on methylmetha acrylic resins

Ultrasonic velocity and absorption were studied in autocure and heatcure resin monomers at different temperatures. Ultrasonic velocity increased in the autocure sample while absorption was reduced. This is attributed to the presence of certain structural factors such as hydrogen bonding.     

Ultrasound velocity and density studies in some refined and unrefined edible oils

Density and ultrasonic velocity at a frequency of 3?MHz and in the temperature range 298–333?K are measured in some of the refined and unrefined edible oils, namely coconut oil, castor oil, sunflower oil, kardi (safflower oil) and groundnut oil, which are predominantly used in south India. Velocity has been observed to be decreasing with temperature nonlinearly in some oils in the temperature range studied. This is in agreement with others' observations made in different oils and fats. Velocity change with temperature is attributed to change in intermolecular distance with temperature and the nature of variation depends on the internal molecular dynamics. Density of all the oils has been found to be decreasing with temperature. Various physical parameters such as specific volume, molar sound velocity, adiabatic compressibility, molar compressibility and intermolecular free length have been estimated using measured data on velocity and density.     

Ultrasonic velocity and apparent isentropic compressibilities in mixtures of nonelectrolytes

Ultrasonic velocities have been determined for binary mixtures of pyridine + n-alkanol (C₁-C₁₀) over the whole composition range at 25‡C. The excess isentropic compressibilities K _S ^E and apparent molar isentropic compressibilities K_Φ,s are estimated from these measurements. The K _S ^E values are negative for all the systems over the complete mole fraction range except pyridine + decanol for which small positive values are obtained. The standard partial molar isentropic compressibilitiesK‡ of the alkanols are positive and increase linearly with the chain length of the alkanol molecules. It indicates that a methylene functional group makes a positive contribution to the expansion coefficient of a solute in these mixtures.     

Influence of samarium on the hydrogenation properties of supported nickel catalyst

The effect of samarium on Ni/sepiolite catalyst was investigated by benzene hydrogenation, methanation of carbon dioxide, CO chemisorption, XPS and CS₂ poisoning, respectively. The result indicates that a proper amount and impregnation order of samarium in the preparation of Ni-Sm/sepiolite catalyst are very efficient to improve the catalytic activity and anti-sulfur ability. At the same time, the mechanism of samarium improving hydrogenation activity of Ni/sepiolite is presented.     

The influence of the temperature on the formation of samarium nitrato complexes

The stability constants of the Sm(NO₃)²⁺ complex were determined at three temperatures, using the solvent extraction method. It was found that:K ₁ ⁰ =63.6 at 17°C, 30.3 at 35°C, 20.1 at 50°C. This corresponds with the formation of a Sm(H₂O)(NO₃)²⁺ complex at 17°C and a Sm(H₂O)₂(NO₃)²⁺ complex at 50°C.

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Der Einfluß der Temperatur auf die Bildung von Samarium Nitrato Komplexen

Zusammenfassung Die Stabilitätskonstanten von Sm(NO₃)²⁺ Komplexen wurden mittels der Lösungsmittelextraktionsmethode bei drei Temperaturen bestimmt. Dabei ergab sichK ₁ ⁰ =63.6 bei 17°C, 30.3 bei 35°C und 20.1 bei 50°C. Das entspricht der Bildung eines Sm(H₂O)(NO₃)²⁺ Komplexes bei 17°C und eines Sm(H₂O)₂(NO₃)²⁺ Komplexes bei 50°C.

     

Behavior of samarium inhaled by mice: Exposure length and time-dependent change

Distribution of samarium (Sm) in mice was investigated after inhalation exposure to Sm₂O₃ particles of 5 μm diameter and 15 mg/m³. Concentrations of Sm were determined by ICP-MS. Samarium was mainly distributed in lung, and the concentrations were varied, depending on the exposure length and time passed following final inhalation. Samarium concentrations in bone were lower than in lung, however, increased after cessation of the inhalation, suggesting that a part of Sm in lung was transported to bone via the blood stream.     

Polymerization of acrylonitrile initiated by samarium diiodide in the presence of hexamethylphosphoramide

The paper presents the polymerization of acrylonitrile (AN) initiated by samarium diiodide (SmI₂) combining with hexamethylphosphoramide (HMPA) for the first time. The effects of various parameters, such as reaction temperature, AN/Sm and HMPA/Sm molar ratios, reaction time on the polymer yield and its molecular weight were discussed. On the basis of both IR and NMR analysis of resulted polymers, a single-electron-transfer initiation mechanism of AN as radical anion was proposed for this polymerization, which was further sustained by the copolymerization of AN with ε-caprolactone and 2,2-dimethyltrimethylene carbonate, respectively.     

Absorption and velocity of ultrasonic waves in thiophene, o-, p-xylenes and their mixtures

The results of acoustic measurements of velocity and absorption in three pure liquids: thiophene, p-and m-xylenes and their mixtures are presented. The experiments for the mixtures of thiophene were carried out by Eggers' method at frequencies 0.3–5 MHz, and for pure liquids by the pulse method in the frequency range 10 MHz–10 GHz, all at 293.15 K except for thiophene (at 281 and 333 K).

The absorption in thiophene shows that all vibrational degrees of freedom take part in the observed relaxation, caused by the Kneser processes. This process can be described as a vibrational relaxation with one relaxation time. Absorption in the mixtures decreased when increasing the amount of xylenes, as predicted by theory of gases, thus suggesting that the absorption is probably due to the same phenomenon as in gases.     

Solutions of alkali soaps and water in fatty acid V. Measurements of water vapour pressure and electrical conductivity

Measurements of water pressure and electrical conductivity have contributed to show that the extended, isotropic liquid L₂-phase region in the system sodium octanoate/ octanoic acid/water may be divided into several subregions, inside which the character of the system is different. In the non-aqueous part of the phase and at low contents of water and more than about three moles of octanoic acid per mole of sodium octanoate the character is that of a solution of acid sodium octanoate in octanoic acid. At high water contents the L₂-phase has the character of a solution of acid sodium octanoate in water. Intermediately there is a large region where the character of the phase is reminiscent of a hydrated acid sodium octanoate in fluid state. In this region the content of octanoic acid is below three moles per mole of sodium octanoate and the maximal water content is about that bound to the polar groups.In the intermediate region the water vapour pressure is regulated mainly by the extent and type of the bonding of the water to the polar groups, and the electrical conductivity by the migration of free hydrated sodium ions in an environment of hydrated polar groups. In the part of the L₂-phase where the character of the phase is that of an aqueous solution the vapour pressure and conductivity are regulated by the concentration of molecularly dispersed acid sodium octanoate and its ions in water.     

Preparation and crystal structure of new samarium complexes with glutamic acid

Samarium complexes with glutamic acid containing cationic [Sm₂(Glu)₂(H₂O)₈]⁴⁺ units have been prepared and characterized by using elemental analysis, infrared absorption spectra and thermal analysis. In addition, the crystal and molecular structure of [Sm₂(Glu)₂(H₂O)₈](ClO₄)₄·3H₂O was determined by X-ray diffraction. The presence of glutamic acid in the Sm coordination sphere allows the formation of a singular extended 2D arrangement. Sm atoms are nine coordinated, in a monocapped square antiprism geometry. They are connected by means of different μ-COO⁻ bridges, involving - and γ-carboxylate groups of the amino acid.     

Dependence of ultrasonic velocity on structure in a homologous series of nonelectrolytes in aqueous medium

Ultrasonic velocities (u) have been measured for various concentrations (x), and (du/dx) _x=0 evaluated, in dilute aqueous solutions of nonelectrolytes which form solid clathrate structures of type II, or are members of a homologous series of alcohols, ketones or cyclic ethers. Changes in (du/dx) _x=0 in these classes of compounds were found to be correlated with changes in structure. Elongation of the hydrocarbon chain by addition of a CH₂ group is accompanied by an increase in (du/dx) _x=0 . Replacement of C?C by C=C, C?H by C?OH, CH₂) by ?O?, and CH?OH by C=O, lead to decreases in (du/dx) _x=0 . It is postulated that maximal values of (du/dx) _x=0 should be observed for hydrocarbons with only single C?C bonds.