Derived partial molar properties investigations of viscosity Arrhenius parameters in formamide + N,N-dimethylacetamide systems at different temperatures

Excess properties calculated from the literature values of experimental density and viscosity in N,N-dimethylacetamide + formamide binary mixtures between 298.15 K and 318.15 K can lead us to test different correlation equations as well as their corresponding relative functions. Inspection of the Arrhenius activation energy Ea and the enthalpy of activation of viscous flow ΔH* shows very close values. Here, we can define partial molar activation energies Ea₁ and Ea₂ for N,N-dimethylacetamide and formamide, respectively, along with their individual contribution separately. Correlation between the two Arrhenius parameters of viscosity in all compositions shows the existence of two main distinct behaviours separated by the mole fraction equal to 0.3 of N,N-dimethylacetamide. In addition, the correlation between Arrhenius parameters reveals interesting Arrhenius temperature, which is closely related to the vaporisation temperature in the liquid vapour equilibrium and the limiting corresponding partial molar properties can permit us to predict the boiling points of the pure components.     

A novel approach to discuss the viscosity Arrhenius behaviour and to derive the partial molar properties in binary mixtures of N,N-dimethylacetamide with 2-methoxyethanol in the temperature interval (from 298.15 to 318.15) K

Calculation of excess properties in N,N-dimethylacetamide + 2-methoxyethanol binary mixtures at (298.15, 308.15 and 318.15) K from experimental density, viscosity and sound velocity values were presented in previous work. Applications of these experimental values to test different correlation equations as well as their corresponding relative functions were also reported. Considering the quasi-equality between the Arrhenius activation energy Ea and the enthalpy of activation of viscous flow ΔH*, here we can define partial molar activation energy Ea₁ and Ea₂ for N,N-dimethylacetamide and 2-methoxyethanol, respectively, along with their individual contribution separately. Correlation between Arrhenius parameters reveals interesting Arrhenius temperature with a comparison to the vaporisation temperature in the liquid vapour equilibrium, and the limiting corresponding partial molar properties that can permit us to estimate the boiling points of the pure components.     

A partial derivatives approach for estimation of the viscosity Arrhenius temperature in N,N-dimethylformamide + 1,4-dioxane binary fluid mixtures at temperatures from 298.15 K to 318.15 K

Excess properties calculated from the literature values of experimental density and viscosity in N,N-dimethylformamide (DMF) + 1,4-dioxane (DO) fluid binary mixtures (from 303.15 to 318.15) K can lead us to test the different correlation equations as well as their corresponding relative functions. Inspection of the Arrhenius activation energy Ea and the enthalpy of activation of viscous flow ?H* shows very close values; here we can define partial molar activation energy Ea₁ and Ea₂ for DMF and DO, respectively, along with their individual contribution separately. Correlation between the two Arrhenius parameters of viscosity in all compositions shows the existence of the primary distinct behaviours separated by particular mole fractions in DMF. In addition, we add that the correlation between Arrhenius parameters reveals interesting Arrhenius temperature (T_A), which is closely related to the vaporisation temperature in the liquid–vapour equilibrium; moreover, the limiting corresponding partial molar properties allow us to estimate the boiling points of the pure components.     

Estimation of the normal boiling points of water and 1,2-dimethoxyethane through the viscosity–temperature dependence in the corresponding binary mixtures

Excess quantities calculated from literature values of experimental density and viscosity in 1,2-dimethoxyethane + water binary systems (from 303.15 to 323.15 K) can lead us to test different correlation equations as well as their corresponding derivative properties. Inspection of the Arrhenius activation energy (Ea) and the enthalpy of activation of viscous flow (ΔH*) shows very close values; here, we can define partial molar activation energies Ea₁ and Ea₂ for 1,2-dimethoxyethane and water, respectively, along with their individual contribution separately. Correlation between the two Arrhenius parameters of viscosity in all compositions shows existence of main distinct interaction behaviours delimited by particular mole fractions in 1,2-dimethoxyethane. Moreover, we add that correlation between Arrhenius parameters reveals interesting Arrhenius temperature which is closely related to the vapourisation temperature in the liquid vapour equilibrium, and the limiting corresponding partial molar properties can permit us to estimate the boiling points of the pure components.     

Viscosity Arrhenius activation energy and derived partial molar properties in N,N-Dimethylacetamide + water binary mixtures at temperatures from 298.15 to 318.15 K

Calculation of excess properties in N,N-dimethylacetamide + water binary mixtures at (298.15, 308.15 and 318.15) K from experimental density, viscosity and sound velocity values were presented in previous work. Applications of these experimental values to test different correlation equations as well as their corresponding relative functions were also reported. Considering the quasi-equality between the Arrhenius activation energy Ea and the enthalpy of activation of viscous flow ΔH*, here we can define partial molar activation energy Ea ₁ and Ea ₂ for N,N-dimethylacetamide and water respectively along with their individual contribution separately. Correlation between the two Arrhenius parameters of viscosity in all the domains of composition shows the existence of two main distinct behaviours separated by a stabilised structure in a short range of mole fraction in N,N-dimethylacetamide from 0.2 to 0.3. We add that correlation reveals interesting Arrhenius temperature which is closely related to the vapourisation temperature in the liquid vapour equilibrium.     

On the viscosity Arrhenius temperature for methanol + N,N-dimethylformamide binary mixtures over the temperature range from 303.15 to 323.15 K

Excess properties calculated from literature values of experimental density and viscosity in N,N-dimethylformamide (DMF) + methanol (Met) binary mixtures (from 303.15 to 323.15 K) can lead us to test different correlation equations as well as their corresponding derivative properties. Inspection of the Arrhenius activation energy (E_a) and the enthalpy (ΔH*) of activation of viscous flow shows very close values; here, we can define partial molar activation energies E_a1 and E_a2 for N,N-DMF and Met, respectively, along with their individual contribution separately. Correlation between the two Arrhenius parameters of viscosity in all compositions shows existence of main distinct interaction behaviours delimited by particular mole fractions in N,N-DMF. In addition, we add that correlation between Arrhenius parameters reveals interesting Arrhenius temperature that is closely related to the vaporisation temperature in the liquid vapour equilibrium, and the limiting corresponding partial molar properties can permit us to estimate the boiling points of the pure components.     

Estimation of boiling points by investigations of viscosity Arrhenius behaviours in Methyl Benzoate + n-Hexane binary liquid systems at atmospheric pressure

Calculation of excess properties in methyl benzoate + n-Hexane binary liquid mixtures at (303.15, 308.15 and 313.15) K from experimental viscosity and density values was presented in earlier work. Investigations of these experimental values to test correlation quality of different equations as well as their corresponding relative functions were also reported. Considering the quasi-equality between the enthalpy of activation of viscous flow ΔH* and the viscosity Arrhenius activation energy Ea, here we can define partial molar activation energy Ea₁ and Ea₂ for methyl benzoate with n-Hexane, respectively, along with their individual contribution separately. Correlation between Arrhenius parameters brings to light interesting Arrhenius temperature with a comparison to the temperature of vaporisation in the liquid vapour equilibrium, and the limiting corresponding partial molar properties that can permit us to predict value of the boiling points of the pure components. New empirical equations for estimating the boiling temperature are proposed.     

Viscosity Arrhenius activation energy and derived partial molar properties in of N,N-dimethylacetamide + 2-ethoxyethanol binary mixtures at temperatures from 298.15 K to 318.15 K.

Calculation of excess properties in N,N-dimethylacetamide + 2-ethoxyethanol binary mixtures at (298.15, 308.15 and 318.15) K from experimental density, viscosity and sound velocity values were presented in previous work. Applications of these experimental values to test different correlation equations as well as their corresponding relative functions were also reported. Considering the quasi-equality between the Arrhenius activation energy Ea and the enthalpy of activation of viscous flow ?H*, here we can define partial molar activation energy Ea1 and Ea2 for N,N-dimethylacetamide and 2-ethoxyethanol, respectively, along with their individual contribution separately. Correlation between the two Arrhenius parameters of viscosity in all the domains of composition shows the existence of two main distinct behaviours separated by a stabilised structure in a short range of mole fraction in N,N-dimethylacetamide from 0.14 to 0.45. We add that correlation reveals interesting Arrhenius temperature, which is closely related to the vaporisation temperature in the liquid vapour equilibrium.     

The reduced Redlich–Kister equations for correlating volumetric and viscometric properties of N,N-dimethylacetamide + dimethylformamide binary mixtures at temperatures from 298.15 to 318.15 K

Excess molar volumes and viscosity deviations in N,N-dimethylacetamide?+?dimethylformamide binary mixtures at 298.15, 308.15 and 318.15?K were calculated from experimental density and viscosity data presented in the previous work. Here these experimental values were used to test the applicability of the correlative reduced Redlich–Kister equation and the recently proposed Herráez equation. Their correlation ability at different temperatures, and the use of different number of parameters, is discussed for the case of limited experimental data. These relative functions are important to reduce the effect of temperature and, consequently, to reveal the effects of different types of interactions. Limiting excess partial molar volumes at infinite dilution were deduced from different methods, parameters of molar Gibbs energy of activation of viscous flow against compositions were investigated. The results of these observations have been interpreted in terms of structural effects of the solvents. ¹H-NMR studies of these mixtures are also reported.     

The Relative Reduced Redlich–Kister Equations for Correlating Excess Properties of N,N-Dimethylacetamide + Water Binary Mixtures at Temperatures from 298.15 K to 318.15 K

Excess molar volumes, viscosity deviations, and isentropic compressibility changes in N,N-dimethylacetamide + water binary mixtures at (298.15, 308.15 and 318.15)?K were calculated from experimental density, viscosity and sound velocity results presented in previous work. Here these experimental values were used to test the applicability of the correlative reduced Redlich?CKister equation and the recently proposed Herráez equation, as well as their corresponding relative functions. Their correlation ability at different temperatures, and the use of different numbers of parameters, are discussed for the case of limited experimental data. The relative functions are important to reduce the effect of temperature and, consequently, to reveal the effects of different types of interactions. Values of the limiting excess partial molar volume at infinite dilution were deduced using different methods. Also, the activation parameters and partial molar Gibbs energy of activation of viscous flow were analyzed as functions of composition. Correlation between the two Arrhenius parameters of viscosity in all composition domains show the existence of two distinct behaviors, separated by a stabilized structure over a short range of mole fractions from (0.2?to?0.3) in N,N-dimethylacetamide. In this regard, a correlation equation recently proposed by Belda has also been applied to the present system for deriving molar volume properties, in order to assess the validity of the proposed equation,     

Reaction of iodo(trimethyl)silane with <Emphasis Type="Italic">N,N</Emphasis>-dimethyl carboxylic acid amides

The reactions of iodo(trimethyl)silane with N,N-dimethylformamide and N,N-dimethylacetamide Me₂NCOR (R = H, Me) at a molar ratio of 1: 2 involved mainly cleavage of the N-C(=O) bond with formation of up to 80% of N,N-dimethyltrimethylsilylamine Me₃SiNMe₂ and the corresponding acyl iodide RCOI. In the reaction with N,N-dimethylformamide, formyl iodide HCOI was detected for the first time by gas chromatography-mass spectrometry. The contribution of Me-N bond cleavage, leading to N-methyl-N-trimethylsilyl derivative Me(Me₃Si)NCOR and methyl iodide was considerably smaller. Another by-product was the corresponding N-methyl imide MeN(COR)₂ formed by reaction of the initial amide with acyl iodide. The primary intermediate in the reaction of iodo(trimethyl)silane with DMF and DMA is quaternary ammonium salt [Me₂(Me₃Si)N⁺COR] I⁻ which decomposes via dissociation of the N-CO and N-Me bonds.     

Validation of a liquid chromatography-tandem mass spectrometry method for simultaneous quantification of N,N-dimethylacetamide and N-monomethylacetamide in pediatric plasma

N,N–dimethylacetamide is an excipient used in intravenous busulfan formulations, a drug used in hematopoietic stem cell transplantation conditioning. The aim of this study was to develop and validate a liquid chromatography-tandem mass spectrometry method for simultaneous quantification of N,N-dimethylacetamide, and its metabolite N-monomethylacetamide in plasma from children receiving busulfan. A 4 μl aliquot of patient plasma was extracted using 196 μl 50% methanol solution and quantified against calibrators prepared in the extraction solvent given negligible matrix effects across three concentrations. ⁹[H₂]-N,N-dimethylacetamide was used as an internal standard. Separation of N,N-dimethylacetamide and N-monomethylacetamide was achieved using a Kinetex EVO C18 stationary phase (100 mm × 2.1 mm × 2.6 μm) running an isocratic mobile phase of 30% methanol containing 0.1% formic acid at a flow of 0.2 ml/min over 3.0 min. The injection volume was 1 μl. Calibration curves for N,N-dimethylacetamide and N-monomethylacetamide were linear up to 1200 and 200 μg/L, respectively, with a lower limit of quantification 1 μg/L for both analytes. Calibrator accuracy and precision were within ± 10% of the test parameters across four concentration levels. Analytes were stable over 14 days at three different storage conditions. This method was successfully applied to measure N,N-dimethylacetamide and N-monomethylacetamide concentrations in a total of 1265 plasma samples from 77 children.     

Apparent molar volumes,heat capacities,and molecular excluded volumes of methylated,hydroxy and methoxy derivatives of 1-methylcytosine in aqueous solutions at 25°C

Densities and specific heat capacities of aqueous solutions: 1-methylcytosine; 1-methyl-N⁴-hydroxycytosine; 1,5-dimethylcytosine; I,N⁴-dimethylcytosine; 1,5-dimethyl-N⁴-hydroxycytosine; 1-methyl-N⁴-methoxycytosine; 1,N⁴,N⁴-trimethylcytosine, 1,5-dimethyl-N⁴-methoxycytosine were determined using flow calorimetry and flow densimetry at 25°C. Apparent molar volumes and heat capacities were then determined. Molecular excluded volumes were evaluated. A relationship was found between the values of the increments in partial molar values and the kind of groups substituted. Four types of contributions were distinguished: substitution of hydrogen on C, N, and O (in OH group on N4) atoms by CH₃ group and replacement of hydrogen on N4 atom by OH group. The correlation between the experimental partial molar volumes and calculated molecular excluded volumes was also elaborated.     

The relative reduced Redlich–Kister equations for correlating excess properties of N,N-dimethylacetamide + 2-methoxyethanol binary mixtures at temperatures from 298.15 K to 318.15 K

Knowledge and prediction of physicochemical properties of binary mixtures is of great importance for understanding intermolecular interactions. The literature shows that most such systems exhibit non-linear behaviour. Excess molar volumes, viscosity deviations and isentropic compressibility changes in N,N-dimethylacetamide?+?2-methoxyethanol binary mixtures at 298.15, 308.15 and 318.15?K were calculated from experimental density, viscosity and sound velocity data presented in previous work. Here these experimental values were used to test the applicability of the correlative reduced Redlich–Kister equation and the recently proposed Herráez equation as well as their corresponding relative functions. Their correlation ability at different temperatures, and the use of different numbers of parameters, is discussed for the case of limited experimental data. These relative functions are important to reduce the effect of temperature and, consequently, to reveal the effects of different types of interactions. Limiting excess partial molar volume at infinite dilution were deduced from different methods, activation parameters and partial molar Gibbs energy of activation of viscous flow against compositions were investigated. The results of these observations have been interpreted in terms of structural effects of the solvents. In this frame, a correlating equation is recently proposed by Belda and in order to assess the validity of the proposed equation, it has also been applied to the present system for molar volume properties.     

Mechanism of the oxidation reaction of Cu with N2O via nonadiabatic electron transfer

We treat the present work as an attempt to elucidate the mechanism of the oxidation reaction of the Cu atom by nitrous oxide based on our recent work (Kryachko, E. S.; Vinckier, C.; Nguyen, M. T. J Chem Phys 2001, 114, 7911) on the electron attachment to this molecule. We suggest that the title reaction in its Arrhenius regime occurs via the nonadiabatic electron transfer from Cu to the oxygen atom at the crossing of the potential energy surfaces Cu(4s ²S_1/2) + N₂O(X ¹Σ⁺) and Cu⁺ + N₂O^?, where the latter is linked to the complex N₂O^? originated from the higher‐energy T‐shape N₂O molecule and discovered in the aforementioned work. The calculations performed in the present work using a variety of quantum chemical methods support the proposed model. We also show the existence of other reaction pathways of the title reaction that, we believe, contribute to its non‐Arrhenius behavior observed experimentally at T > 1190 K. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Comparative theoretical study of the dissociation process of the isoelectronic molecules BH3CO,CH2CO,HNCO, CO2 and BH3N2, CH2N2, HN3, N2O

Anab initio study of the electronic structure of several 22-electrons molecules is presented. The equilibrium geometries of their ground state are calculated at the SCF level using the 6–31G basis set and are found to be in good agreement with the experimental geometries. The dissociation process of these molecules leading to the isoelectronic products CO or N₂ on the one hand and BH₃, CH₂, NH and O on the other hand is studied. The least-energy dissociation paths of the ground states determined at the SCF level are compared on the basis of electron density interactions. The dissociation energies corresponding to the two lowest dissociation channels are calculated. In these calculations, the correlation energy is taken into account using a non-variational method developed previously. The calculated values of dissociation energies are in good agreement with the existing experimental values. The results permit to predict values for HNCO, BH₃CO and CH₂N₂ and to confirm the instability of BH₃N₂.Aspirant du Fonds National Belge de la Recherche Scientifique.     

Cellulose dissolution in lithium chloride/N,N-dimethylacetamide solvent system: Relevance of kinetics of decrystallization to cellulose derivatization under homogeneous solution conditions

Rate constants and activation parameters for decrystallization of Avicel PH-101 cellulose, and bagasse-based cellulose in presence of LiCl/N,N-dimethylacetamide solvent system have been determined from dependence of the index of crystallinity of cellulose, Ic, on time, under nonisothermal conditions. Calculated rate constants and activation parameters are negligibly dependent on the degree of polymerization of the natural polymer. Under experimental conditions used, derivatization of cellulose can be started after 3 h of cellulose–solvent contact. The relevance of our results to the industrial application of derivatization under homogeneous solution conditions is discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3738–3744, 1999     

Sels de Pyrylium. XVIII. Etude par RMN du Carbone-13 de Sels d'Aminopyrylium et des Barrières de Rotation dans quelques Cations N,N-Diméthylaminopyrylium

The C-2—N bond of 2-N,N-dimethylaminopyrylium cations has a partial π character due to the conjugation of the nitrogen lone-pair with the ring. The values of ΔG^≠, ΔH^≠, ΔS^≠ parameters related to the corresponding hindered rotation have been determined by ¹³C NMR total bandshape analysis. This conjugation decreases the electrophilic character of carbon C-4 so that the displacement of the alkoxy group is no longer possible. Such a hindered rotation also exists in 4-N,N-dimethylaminopyrylium cations and the corresponding ΔG^≠ parameters have been evaluated. Comparison of these two cationic species shows that hindered rotation around the C—N bond is larger in position 4 than in position 2. Furthermore, the barrier to internal rotation around the C-2? N bond decreases with increasing electron donating power of the substituent at position 4. ΔG^≠ values decreases from 19.1 kcal mol^?1 (79.9 kJ mol^?1) to 12.6 kcal mol^?1 (52.7 kJ mol^?1) according to the following sequence for the R-4 substituents: -C₆H₅, -CH₃, -OCH₃, -N(CH₃)₂.     

Complex Permittivity Spectra of Binary Pyridine–Amide Mixtures Using Time–Domain Reflectometry

Frequency spectra of the complex permittivity for pyridine–amide binary mixtures have been determined over the frequency range 10 MHz to 10 GHz, at 5, 15, 25, and 40°C, using the time–domain reflectometry method, for 11 compositions of each pyridine–amide system, e.g., formamide, N-methylformamide, and N,N-dimethylformamide. The relaxation in these systems can be described by a single relaxation time using the Debye model. The static dielectric constant, relaxation time, the corresponding excess dielectric properties, Kirkwood correlation factor, and molar activation energy of the mixtures have been determined. The excess permittivity is found to be positive in the amide-rich region and negative in the pyridine-rich region. The excess inverse relaxation time is negative, except in the pyridine-rich region. The static dielectric constants for the mixtures have been fitted with the modified Bruggeman model. The temperature-dependent relaxation times show the expected Arrhenius behavior.