Apparent molar and partial molar volumes of aqueous ceric ammonium nitrate solutions at 20, 25, 30, and 35°C

Present paper reports the measured densities (ρ) and refractive indices (n _D) of aqueous solutions of ceric ammonium nitrate (CAN) at 20, 25, 30, and 35°C in different concentrations of solution. Apparent molar volumes (φ_v) have been calculated from the density data at different temperatures and fitted to Massons relation to get limiting partial molar volumes (? _v ⁰ ) of CAN. Refractive index data were fitted to linear dependence over concentration of solutions and values of constant K and n _D ⁰ for different temperatures were evaluated. Specific refractions (R _D) of solutions were calculated from the refractive index and density data. Concentration and temperature effects on experimental and derived properties have been discussed in terms of structural interactions.     

Apparent and standard molar volumes and heat capacities of aqueous Ni(ClO4)2 from 25 to 85°C

Apparent molar heat capacities and volumes of aqueous Ni(C10₄)₂ were measured from 25 to 85°C over a concentration range of 0.02 to 0.8 mol-kg^-1 using a Picker flow microcalorimeter and a Picker vibrating-tube densimeter. An extended Debye-Hückel equation was fitted to the experimental data to obtain expressions for the apparent molar properties as functions of ionic strength for Ni(ClO₄)₂(aq). The standard-state partial molar properties for Ni(C10₄)₂(aq) in the temperature range 25 to 85°C were obtained and can be expressed by empirical equations as 97787 and withT in K. The standard partial molar heat capacities and volumes for Ni²⁺ (aq) from 25 to 86°C were obtained by using the additivity rule and data for ClO^- ₄(aq) in the literature. These values were extrapolated to 300°C by employing the Helgeson-Kirkham-Flower (HKF) equations, amended to include a standard-state correction term.     

Synthesis of γ-butyrolactone fused cyclooctene

The expeditious route for the synthesis of γ-butyrolactone fused cyclooctene starting from the γ-butyrolactone fused cyclopentane through bicyclo[4.2.1]nonan-9-one is reported. Retro-Dieckmann’s condensation of bicyclo[4.2.1]nonan-9-one in presence of sodium methoxide and methanol furnished γ-butyrolactone fused cyclooctene in good yield. Surprisingly, the stereochemistry of ring-junction of γ-butyrolactone fused cyclooctene is different from the γ-butyrolactone fused cyclopentane, and the position of new ester group, which were confirmed unambiguously by X-ray analysis.     

Apparent molar volumes and apparent molar heat capacities of aqueous solutions ofα- andβ-cyclodextrins at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa

Apparent molar heat capacities C_{p, φ}and apparent molar volumesV_φ were determined for aqueous solutions of α - and β -cyclodextrins at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa. The molalities investigated ranged from 0.008 mol · kg ^− 1to 0.12 mol · kg ^− 1forα -cyclodextrin and from 0.004 mol · kg ^− 1to 0.014 mol · kg ^− 1for β -cyclodextrin. We used a vibrating-tube densimeter (DMA 512P, Anton PAAR, Austria) to determine the densities and volumetric properties. Heat capacities were obtained using a twin fixed-cell, power-compensation, differential-output, temperature-scanning calorimeter (NanoDSC 6100, Calorimetry Sciences Corporation, Spanish Fork, UT, USA). Equations were fit by regression to our experimental (V_φ, T, m) and (C_{p, φ},T , m) results. Infinite dilution partial molar volumes V₂^oand heat capacities C_p,2^owere obtained over the range of temperatures by extrapolation of these surfaces to m =  0.     

Apparent molar volumes of aqueous calcium chloride to 250°C, 400 bars,and from molalities of 0.242 to 6.150

Relative densities of CaCl ₂ (aq) with 0.22ml(mol-kg^–1)6.150 were measured with vibrating- tube densimeters between 25 and 250°C and near 70 and 400 bars. Apparent molar volumes V calculated from the measured density differences were represented with the Pitzer ioninteraction treatment, with appropriate expressions chosen for the temperature and pressure dependence of the virial coefficients of the model. It was found that the partial molar volume at infinite dilution V ^o , and the second and third virial coefficients B ^V and C ^V , were necessary to represent V near the estimated experimental uncertainty. The ionic-strength dependent ^(1)v term in the B ^V coefficient was included in the fit. The representation for V has been integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. The volumetric data indicate that the logarithm of the mean ionic activity coefficient, ln ±(CaCl ₂ ), increases by a maximum of 0.3 at 400 bars, 250°C, and 6 mol-kg^–1 as compared with its value at saturation pressure.     

Reaction of imidazole and its 2-alkyl derivatives with γ-butyrolactone

Reaction of imidazole with -butyrolactone gives N-alkylation and N-acylation products depending upon the reaction conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1491–1493, November, 1992.     

Changes in the composition of the solvation shell of lithium ions in γ-butyrolactone upon addition of 15-crown-5 as studied by quantum chemistry

Quantum chemical modeling of Li⁺ ion transfer from the solvation shell of γ-butyrolactone (GBL) as the solvent to the cavity of 15-crown-5 (15C5) macrocyclic ligand was carried out. Calculations were performed using the PBE nonempirical density functional and an extended basis for the SBK pseudopotential. The solvation energy was included in the framework of the polarizable continuum model. The calculated geometric parameters of GBL and 15C5 molecules are in good agreement with experimental X-ray data. The energies and structures of the Li(GBL) _n ⁺ (n = 1–5) complexes and Li(GBL) _m (15C5)⁺ (m = 0–3) mixed complexes were calculated. The binding energy of the fifth GBL molecule is low; therefore, the Li⁺ ion is mainly surrounded by four GBL molecules. The formation of mixed complexes by consecutive displacement of GBL molecules from the solvation shell of the lithium ion leads to structures with the coordination number 5. The equilibrium constants of these processes were used to determine the dependence of the composition of the solvation complexes on the concentration of 15C5 in the system. The concentrations of the Li(15C5)⁺ and Li(GBL)(15C5)⁺ complexes appeared to be comparable. The revealed structural features of the Li⁺ solvation complexes in the GBL-15C5 system were used to analyze the operating efficiency of lithium power sources.     

The stable planar conformation of the γ-butyrolactone ring in solution

<正>The conformations ofγ-butyrolactone ring in solution were deduced on the basis of ~1H NMR spectra of geminal protons of the butyrolactone ring.A series of optically pure(Z)-(-)-4-(1'-alkoxyl-1'-carbalkoxy-methylene)-5(R)[(1R)-menthyloxy]-γ-butyr-olactones with a stable planar conformation of γ-butyrolactone ring were found.     

Palladium-catalyzed epimerization of γ-alkenyl-γ-butyrolactone derivatives

γ-Alkenyl-α,β,γ-trisubstituted-γ-butyrolactones (12-16) and γ-alkenyl-furofurandione derivatives (21-Z-24-Z; 21-E-24-E; 25-Z-28-Z; and 25-E-28-E) were successfully epimerized in high yield by a palladium catalyst.     

Volumetric and viscosimetric properties of N-methyl-2-pyrrolidone with γ-butyrolactone and propylene carbonate

Volumetric properties of N-methyl-2-pyrrolidone (NMP) binary mixtures with γ-butyrolactone (GBL) and propylene carbonate (PC) are calculated from the experimental densities and reported in the temperature range from (293.15 to 323.15) K and at atmospheric pressure (0.1 MPa) over the whole composition range. The excess molar volumes have positive values in the whole concentration range in the case of (NMP + PC) binary mixture, with maximum value at equimolar composition, indicating weaker interactions between the components after the mixing. Two extreme V^E values are observed in (NMP + GBL) system: maximum at x(NMP) = 0.4 and minimum at x(NMP) = 0.9. Negative V^E values in NMP-rich region are the consequence of the better geometrical fit of the molecules. The excess properties of (NMP + GBL) and (NMP + PC) binaries are analyzed using Prigogine–Flory–Paterson theoretical model. An excellent agreement between experimental and theoretical values at equimolar composition is observed. Apparent molar volumes and thermal expansion coefficients are also calculated. Viscosity measurements of the pure components and NMP binary mixtures with GBL and PC were performed in the temperature range from (298.15 to 323.15) K. Using obtained experimental viscosities several semi-empirical equations and models were tested.     

Apparent molar volumes and apparent molar heat capacities of aqueous d-lactose · H2O at temperatures from (278.15 to 393.15) K and at the pressure 0.35 MPa

Apparent molar volumes V_φ and apparent molar heat capacities C_p,φ were determined for aqueous solutions of d-lactose · H₂O at molalities (0.01 to 0.34) mol · kg⁻¹ at temperatures (278.15 to 393.15) K, and at the pressure 0.35 MPa. Our V_φ values were calculated from densities obtained using a vibrating tube densimeter, and our C_p,φ values were obtained using a twin fixed-cell, power-compensation, differential-output, temperature-scanning calorimeter. Our results for d-lactose(aq) and for d-lactcose · H₂O were fitted to functions of m and T and compared with the literature results for aqueous d-glucose and d-galactose solutions. Infinite dilution partial molar volumes V₂^∘ and heat capacities C_p,2^∘ are given over the range of temperatures.     

Effect of temperature on partial molar volumes and viscosities of aqueous solutions of α-dl-Aminobutyric acid,dl-Norvaline and dl-Norleucine

In this work, we present experimental results for partial molar volumes and viscosities of aqueous solutions of α-dl-aminobutyric acid, dl-norvaline and dl-norleucine at 288.15, 293.15, 298.15 and 303.15?K. The thermodynamic behavior of aqueous amino acid solutions is compared with that reported for glycine and α-alanine in water and is discussed in terms of group additivity and electrostriction.

The temperature dependence of the infinite dilution partial molar volumes and the B viscosity coefficients are interpreted in terms of amino acid hydration. According to the usual hydrophobicity criteria, the amino acids considered do not have a hydrophobic character and their behavior is dominated by the polar groups.     

Limiting partial molar volumes at 298.15 K of some open chain and cyclic organic compounds in 1—octanol

Partial molar volumes at 298.15 K in 1—octanol have been determined for some hydrocarbons, ethers, ketones, and water from density measurements carried out with a vibrating-tube density meter.In the transfer process from the pure liquid state to the infinitely dilute solution in 1—octanol, a slight shrinkage is generally observed for solutes showing density values lower than that of the solvent. On the contrary, for solutes with higher density values, a weak expansion is produced.Comparisons are made among the partial molar volumes of organic solutes in 1—octanol, in water, and in other organic solvents. The case of water as a solute in 1—octanol and in many other organic liquids is carefully considered. In non-polar solvents the value of the limiting partial molar volume of water is always larger in respect to the value of the molar volume of pure water, but in polar solvents the contrary occurs. An explanation of this phenomenon is provided and a rationale is given to the value of the limiting partial molar volume of water in 1—octanol and to the trend exhibited by the partial molar volume of water in the 1—octanol/water mixture as water concentration is increased.     

Reactions of cyclopentanone, γ-butyrolactone,and their derivatives with α-hydroxyethyl radicals

The interaction of cyclopentanone, 2-cyclopentenone, 1,3-cyclopentanedione, 3-methyl-1,2-cyclopentanedione, γ-butyrolactone, 2(5H)-furanone, ascorbic acid, and 5,6-O-isopropylidenyl-2,3-O-dimethylascorbic acid with α-hydroxyethyl radicals (α-HER) generated during the radiolysis of deaerated ethanol has been studied in the continuous irradiation mode. The test compounds, except γ-butyrolactone, oxidize α-HER. 2(5H)-Furanone and 2-cyclopentenone give hydroxyethylation products via the free-radical chain mechanism. In contrast to 2(5H)-furanone and 2-cyclopentenone, ascorbic and 5,6-O-isopropylidenyl-2,3-O-dimethyl-L-ascorbic acids are weaker oxidants for α-HER and attach these radicals at the multiple carbon-carbon bonds.     

Temperature dependence of apparent molar volumes and viscosity B-coefficients of amino acids in aqueous potassium thiocyanate solutions from 15 to 35°C

Precise density and viscosity data at 15, 25 and 35°C for solutions of glycine, DL-alanine, L-threonine, -alanine, -aminobutyric acid and -aminocaproic acid in water and in (1m, 3m, 5m) aqueous potassium thiocyanate were measured and the limiting apparent molar volumes V ^o and the B-coefficients calculated. The V ^o and B values were split into the contributions from the NH ₃ ⁺ ,COO^– and CH₂ groups. These data are rationalized on the basis of hydrophillic and hydrophobic interactions between the various groups present in these solutions.Abstracted from the Ph.D Thesis of R. K. Goyal, University of Delhi, 1990.     

A multicoincidence study of fragmentation dynamics in collision of γ-aminobutyric acid with low-energy ions

Fragmentation of the γ-aminobutyric acid molecule (GABA, NH(2)(CH(2))(3)COOH) following collisions with slow O(6+) ions (v≈0.3?a.u.) was studied in the gas phase by a combined experimental and theoretical approach. In the experiments, a multicoincidence detection method was used to deduce the charge state of the GABA molecule before fragmentation. This is essential to unambiguously unravel the different fragmentation pathways. It was found that the molecular cations resulting from the collisions hardly survive the interaction and that the main dissociation channels correspond to formation of NH(2)CH(2)(+), HCNH(+), CH(2)CH(2)(+), and COOH(+) fragments. State-of-the-art quantum chemistry calculations allow different fragmentation mechanisms to be proposed from analysis of the relevant minima and transition states on the computed potential-energy surface. For example, the weak contribution at [M-18](+), where M is the mass of the parent ion, can be interpreted as resulting from H(2)O loss that follows molecular folding of the long carbon chain of the amino acid.     

Theoretical study on decomposition of γ-halo allylalkoxide and β-halo acrylate ions

β, γ-Substituted γ-halo allylalkoxide ions decompose to form a halogen ion, formaldehyde, and an alkyne under mild conditions, for example at room temperature. The E isomer does not differ from the Z isomer in terms of activation energy. We attempted to shed light on the mechanism of the reaction by using ab initio molecular orbital calculations. The observed propensity was confirmed by the present calculation on model molecules, γ-chloro allylalkoxide ions. We conducted further calculations and compared the alkoxide results with a similar reaction of β-haloacrylate ions that release carbon dioxide instead of formaldehyde. This similar reaction needs heating as high as 150°C. The activation energy of the acrylate ions (36–39 kcal mol⁻¹) was calculated to be about 10 kcal mol⁻¹ higher than that of the alkoxide ions. The activation energy of the E acrylate ion is smaller by 0.8 kcal mol⁻¹ than that of the Z isomer at the MP2/6-31+G**//RHF/6-31+G* level of theory. This is consistent with experimental results. While the ready deprotonation from the carboxylic group does not activate the acrylate ion very much, the alkoxide ion is destabilized to a great degree in the process of anion formation. The difficulty in deprotonation that proceeds from the neutral molecule is seen in the difference in the activation energies for the decomposition of the corresponding anions. Therefore, the pK _a of a hydroxy or a carboxylic group plays the leading role in determining the magnitude of activation energies of allyl halides with a negatively charged fragment. Received: 2 July 1998 / Accepted: 9 September 1998 / Published online: 8 February 1999     

Samarium diiodide induced asymmetric synthesis of γ-butyrolactone using chiral auxiliaries derived from isosorbide and isomannide

The asymmetric reductive coupling reaction of various acrylates derived from D-isosorbide and D-isomannide with acetophenone mediated by samarium diiodide to give both enan-tiomers of the optically active γ-butyrolactone was described.The best enantiomeric excess of the products was 60%.