Apparent Molar Volume and Viscosity Studies on Some Carbohydrates in Solutions

Summary.  The apparent molar volume (φ_v) and viscosity (η) of L(+)-arabinose, D(+)-galactose, D(−)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function of solute concentrations at 308.15, 313.15, and 323.15 K, respectively. The apparent molar volume (φ_v) of the carbohydrates was found to be a linear function of the concentration. From a φ_v versus molality (b) plot, the apparent molar volume at infinite dilution (), which is practically equal to the partial molar volume at infinite dilutions () of these substances was determined. The viscosity coefficients B and D for the carbohydrates were calculated on the basis of the viscosity of the solutions and the solvent using the Jones-Dole equation. The activation free energy for viscous flow (ΔG ^≠) of the solutions was also calculated using the Eyring equation. The carbohydrates showed structure making behaviour both in water and in water-Surf Excel solutions. When water-Surf Excel solutions and pure water solutions containing carbohydrate molecules are compared, the former were found to be more structured. The behaviour of these solutes in water and in water-Surf Excel solution systems is discussed in the light of solute–solvent interactions. Corresponding author. E-mail: chemistry_ru@yahoo.com Received March 19, 2002; accepted (revised) July 31, 2002 Published online February 24, 2003     

Volumetric and Viscometric Studies on an Aqueous Urea Solution

Of late there has been a renewed inerest in the thermodynamics and other investigations on the behaviour of urea (denaturants) in aqueous solution which induce changes in structure and properties of proteins including their solubility, denaturation, dissociation into subunits and the activity of enzymes. With this in view, density and viscosity of aqueous urea solutions were determined as a function of concentration at 35, 40, 45, 50 and 55C, respectively. The apparent molal volume $(phi _v )$ of urea was found to be linear function of solute concentration. From the $phi _v$ versus molality ( m ) plot the apparent molal volume at infinite dilution, $phi _v^o$ (taken to be equal to partial molal volume, $bar V_2^o$ ) was determined. Viscosity coefficients B and D were calculated on the basis of the viscosity of the solutions and the solvent concerned using the Jones-Dole equation. The activation parameters for viscous flow $(Delta G^{ne} , ,Delta S^{ne} {rm and }Delta H^{ne} )$ were also calculated by means of the Eyring equation. The data were interpreted in terms of the structure making behaviour of urea in water at 35-55C temperature range.     

NaCl、KCl在蔗糖水溶液中的粘度

报导了在298．15及308．15K下，NaCl、KCl在含有蔗糖5，10，15，20，25％（质量分数w）的水溶液中的密度及粘度数据．计算了在无限稀释条件下，NaCl和KCl在该体系中的粘度B系数及偏摩尔体积．结果发现：两种电解质的B系数随蔗糖含量的增加及温度的升高而增大且对蔗糖水溶液的结构起破坏作用．讨论了该三元体系内部溶质－溶质、溶质－溶剂间的相互作用，同时应用流动过渡状态理论计算了两种电解质在各组成下蔗糖水溶液中的流动活化参数     

不同温度下氨基酸在α-咖啡碱水溶液中的体积、粘度及折光率特性

Measurements of density(ρ), viscosity(η), and refractive index(n), were carried out on α-amino acids, DL-solution at 298.15, 303.15, 308.15, and 313.15 K. These measurements have been carried out to evaluate some important parameters, viz., apparent molar volume (φv), partial molar volume (φv0), transfer volume (φ0v (tr)), viscosity A and B coefficients of Jones-Dole equation, free energies of activation per mole of solvent (△μ0#1) and solute (△μ0#2),enthalpies (△H*) and entropies (△S*) of activation of viscous flow, variation of B with temperature ((a)B/(a)T)P, and molar refractive index (RD). These parameters have been interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.     

Volumetric and Viscometric Studies on Some Inorganic Electrolytes in Water and in Water-SDS Solution Systems

The apparent molal volumes (φ _v ) of NaCl, NaNO₃, NH₄Cl, CuCl₂, CuSO₄, CoSO₄ and MgSO₄ in water and in water-SDS (Sodium dodecyl sulphate) solutions were determined from density measurements at 308.15, 313.15 and 323.15 K respectively. The limiting apparent molal volume at infinite dilution φ ^o _v which is practically equal to the partial molal volume V ^o ₂) of these electrolytes were found to be higher in water-SDS solution systems than those in water solutions. Viscosity coefficients (A and B) for these systems were also determined by Jones-Dole equation. All these electrolytes, except NH₄Cl exhibit structure making behaviour in water and in water-SDS solutions. Ammonium chloride showed structure breaking properties in water and in 0.01 molar water-SDS solutions. In 0.1 molar SDS solution, it showed structure making behaviour at the temperature range studied. The properties of these electrolytes in water and in water-SDS solution systems have been discussed in terms of the charge, size and hydrogen bonding effect.     

不同温度下α-氨基酸在咖啡碱水溶液中的体积、粘度及折光率特性

Measurements of density(ρ), viscosity(η), and refractive index(n), were carried out on α-amino acids, DL-solution at 298.15, 303.15, 308.15, and 313.15 K. These measurements have been carried out to evaluate some important parameters, viz., apparent molar volume (φv), partial molar volume (φv0), transfer volume (φ0v (tr)), viscosity A and B coefficients of Jones-Dole equation, free energies of activation per mole of solvent (△μ0#1) and solute (△μ0#2),enthalpies (△H*) and entropies (△S*) of activation of viscous flow, variation of B with temperature ((a)B/(a)T)P, and molar refractive index (RD). These parameters have been interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.     

Densities and Apparent Molar Volumes of Aqueous H<Subscript><Emphasis Type="Bold">3</Emphasis></Subscript>BO<Subscript><Emphasis Type="Bold">3</Emphasis></Subscript> Solutions at Temperatures from 296 to 573 K and at Pressures up to 48 MPa

Densities of four aqueous H₃BO₃ solutions (0.062, 0.155, 0.315, and 0.529 mol-kg^–1) have been measured in the liquid phase with a constant volume piezometer immersed in a precisely controlled liquid thermostat. Measurements were made at temperatures between 296 and 573 K and pressures from 0.82 to 48 MPa. The total uncertainties of the density, pressure, temperature, and molality measurements were estimated to be less than 0.06%, 0.05%, 10 mK, and 0.0005 mol-kg^–1, respectively. The accuracy of the method was confirmed by PVT measurements on pure water for two isobars (30 and 39 MPa) at temperatures from 313 to 573 K. The experimental and calculated (IAPWS formulation) densities for pure water show excellent agreement which is within their experimental uncertainties (average absolute deviation, AAD=0.012%;). Apparent and partial molar volumes were derived using the measured densities for solutions and pure water, and these results were extrapolated to zero concentration to yield the partial molar volumes of the electrolyte (H₃BO₃) at infinite dilution. The temperature, pressure, and concentration dependencies of the apparent and partial molar volumes were studied. Small pressure and concentration effects on the apparent molar volumes were found at temperatures up to 500 K. The parameters of a polynomial type of equation of state for the specific volume V_sol(P, T, m) as a function of pressure, temperature, and molality were obtained with a least-squares method using the experimental data. The root-mean-square deviation between measured and calculated values from this polynomial equation of state is ±0.2 kg-m^–3 for density. Measured values of the solution densities and the apparent and partial molar volumes are compared with data reported in the literature.     

D<Subscript>2</Subscript>O — H<Subscript>2</Subscript>O Solvent Isotope Effects on the Apparent Molar Volumes of Tetramethyl-<Emphasis Type="Italic">bis</Emphasis>-urea (Mebicarum) Solutions

Densities of solutions of tetramethyl-bis-urea (TMbU) or “Mebicarum” in H₂O and D₂O, with solute mole fraction concentrations (x ₂) ranging up to 3.2 × 10⁻³, have been measured at 288.15, 298.15, 308.15 and 318.15 K using a precision vibrating-tube densimeter. The limiting apparent molar volumes, V _φ,2 ^∞, and expansibilities, E _{p, φ, 2} ^∞, of the solute have been calculated. The isotope effect δ V _φ,2 ^∞(H₂O → D₂O;T) is negative, monotonously decreases in magnitude with temperature and reverses sign at T ≈ 318 K. Water (H₂O, D₂O) and TMbU molecules in infinitely- and highly-dilute aqueous solutions form H(D)-bonded hydration complexes with a high packing density. The hydration of TMbU should be treated as a superposition of two mechanisms, hydrophobic and hydrophilic, with the latter one predominating.     

甘氨酸、L-丙氨酸和L-丝氨酸在尿素水溶液中的体积性质

蛋白质的折叠与解折叠、稳定性、变性行为和酶的活性等都受到环境中其它各种物质影响.作为蛋白质模型分子,氨基酸在混合溶液中的热力学研究近年来引起了广泛重视.尿素在生物体系中的独特地位主要表现在:它是水结构的破坏者,同时又是许多球状蛋白的变性剂.然而,尿素对球状蛋白的变性作用尚未达成共识.     

298.15 K甘氨酰二肽在乙酸钠水溶液中的体积性质

测定了298.15 K三种甘氨酰二肽(甘氨酰甘氨酸、甘氨酰-L-缬氨酸和甘氨酰-L-亮氨酸)在0.5, 1.0, 1.5和2.0 mol&#8226;kg－1乙酸钠水溶液中的密度, 计算了这些肽在乙酸钠水溶液中的表观摩尔体积, 标准偏摩尔体积, 标准偏摩尔转移体积, 理论水化数和体积相互作用参数. 结果表明: 甘氨酰二肽的标准偏摩尔体积和标准偏摩尔转移体积均随乙酸钠浓度的增加而增大, 溶液中离子与肽带电基团/甘氨酰基团(CH2CONH)之间的相互作用大于离子与肽的非极性基团间的相互作用, 乙酸钠和甘氨酰二肽之间主要是对相互作用. 利用共球交盖模型对所研究的肽与乙酸钠之间的体积相互作用进行了解释. 利用氨基酸的标准偏摩尔体积值, 对二肽的标准偏摩尔体积进行了估算, 发现计算值与实验值一致.     

Synthesis and characterization of a new monophosphate (C<Subscript>6</Subscript>H<Subscript>16</Subscript>N<Subscript>2</Subscript>)(H<Subscript>2</Subscript>PO<Subscript>4</Subscript>)<Subscript>2</Subscript>

Chemical preparation, crystal structure, and NMR spectroscopy of a new trans-2,5-dimethylpiperazinium monophosphate are given. This new compound crystallizes in the triclinic system, with the space group P-1 and the following parameters: a = 6.5033(3), b = 7.6942(4), c = 8.1473(5) Å, α = 114.997(3), β = 92.341(3), γ = 113.136(3), V = 329.14(3) ų, Z = 1, and D_x = 1.565 g cm^?3. The crystal structure has been determined and refined to R = 0.030 and R _w(F ²) = 0.032 using 1558 independent reflections. The structure can be described as infinite [H₂PO₄] _n ^n? chains with (C₆H₁₆N₂)²⁺ organic cations anchored between adjacent polyanions to form columns of anions and cations running along the b axis. This compound has also been investigated by IR, thermal, and solid-state, ¹³C and ³¹P MAS NMR spectroscopies and Ab initio calculations.     

Volumetric,Compressibility and Viscometric Approach to Study the Interactional Behaviour of Sodium Cholate and Sodium Deoxycholate in Aqueous Glycyl Glycine

Viscosity, speed of sound (u), and density (ρ) have been measured in aqueous glycyl glycine solution over a temperature range from 293.15 to 313.15 K with a 5 K interlude to evaluate the volumetric and compressibility properties of bio-surfactants, namely sodium cholate (NaC; 1–20 mmol∙kg⁻¹) and sodium deoxycholate (NaDC; 1–10 mmol∙kg⁻¹). Density and viscosity findings provide information on both solute–solute and solute–solvent types of interactions. Many other metrics, such as apparent molar adiabatic compression (κS,φ), isentropic compressibility (κS), and apparent molar volume (Vφ), have been calculated from speed of sound and density measurements, utilising experimental data. The results show that the zwitterionic end group in the glycyl glycine strongly interacts with NaDC and NaC, promoting its micellization. Since the addition of glycyl glycine causes the bio-surfactant molecules to lose their hydrophobic hydration, the observed concentration-dependent changes in apparent molar volume and apparent molar adiabatic compression are likely attributable to changes in water–water interactions. Viscous relaxation time (τ) increases significantly with a rise in bio-surfactant concentration and decreases with increasing temperature, which may be because of structural relaxation processes resulting from molecular rearrangement. All of the estimated parameters have been analysed for their trends with regard to the different patterns of intermolecular interaction present in an aqueous glycyl glycine solution and bio-surfactant system.     

298.15 K下氨基酸在D-木糖水溶液中的体积性质

报道了甘氨酸、L-丙氨酸和L-丝氨酸3种典型氨基酸在D-木糖水溶液中的体积性质.     

Volumetric and Viscometric Properties of Aqueous Solutions of N-Methylformamide, 1,2-Diaminopropane and 2-Methylpropane-2-ol

Density and viscosity of aqueous solutions of N-methylformamide (NMF), 1,2-diaminopropane (DAP) and 2-methylpropane-2-ol (MPL) have been measured precisely over the entire composition range (i.e., 1 ≥ x ₂ ≥ 0) at five equidistant temperatures ranging from 298.15 to 318.15 K. Excess molar volume (V^E _m ) and excess viscosity (η ^E ) have been calculated from measured density and viscosity data, respectively. Excess molar volume and excess viscosity have been fitted by the least squares method to the four parameters Redlich-Kister equation. The results have been interpreted on the basis of (i) interstitial incorporation, (ii) breakdown of the structure of pure liquids, (iii) hydrophobic hydration, (iv) hydrophobic interaction and (v) association between dissimilar liquids.     

Volumetric and Ultrasonic Investigation of Glycylglycine in Aqueous FeCl<Subscript>3</Subscript> Solutions

Viscosity, ultrasonic velocity and density measurements have been carried out for glycylglycine in aqueous FeCl₃ solution as a function of molality at T=288.15 K, 298.15 K and 308.15 K. The experimental data have been used to derive properties such as isentropic compressibility (κ _S ), change in isentropic compressibility (Δκ _S ), relative change in isentropic compressibility (Δκ _S /κ ₀), apparent molar compressibility, volume and their limiting apparent molar quantities along with the constants S _K , S _V and viscosity B-coefficient. The obtained thermodynamic properties have been discussed in terms of molecular interactions.     

Interactions of Proline in Non-aqueous Anionic, Cationic and Nonionic Surfactants at Different Temperatures

Density and viscosity data of proline (Pro) in sodium dodecyl sulfate/cetyltrimethylammonium bromide/poly (oxyethylene) isooctyl phenyl ether in formamide were measured at 298.15, 303.15, 308.15, and 313.15 K and 0.1 MPa. The density data were utilized to evaluate standard partial molar volumes ( ) and partial molar isobaric expansibility ( ). The viscosity data were used to evaluate A- and B-coefficients, free energy of activation of viscous flow ( ) and ( ), per mole of solvent and solute respectively, enthalpy (ΔH^*) and entropy (ΔS^*) of activation of viscous flow. The results obtained were utilized in the qualitative elucidation of the Pro-surfactant/formamide and Pro-Pro interactions in the present systems.     

Second Dissociation Constant of H<Subscript>2</Subscript>Te and the Absorption Spectra of HTe<Superscript>–</Superscript>, Te<Superscript>2–</Superscript> and Te<Subscript>2</Subscript><Superscript>2–</Superscript> in Aqueous Solution

We have measured the second acid dissociation constant, K _2a , at several ionic strengths for hydrogen telluride (H₂Te) using the Charge Transfer to Solvent (CTTS) uv spectra of its anions HTe⁻ and Te²⁻. Since it is produced in our solutions, we have also determined the spectra of Te₂ ²⁻ both in the uv and in the visible regions. At 25 ^∘C, K _2a = (1.28 ± 0.02) × 10⁻¹² by extrapolation to zero ionic strength. Its value at an ionic strength equal to 0.5 mol.dm^-3 was estimated to be (8.7 ± 0.2) × 10⁻¹². The solution thermodynamics of these species are also discussed and comparisons are made to related acids.     

不同温度下脯氨酸在非水阴离子、阳离子及非离子型表面活性剂中的相互作用

Density and viscosity data of proline (Pro) in sodium dodecyl sulfate/cetyltrimethylammonium bromide/poly (oxyethylene) isooctyl phenyl ether in formamide were measured at 298.15, 303.15, 308.15, and 313.15K and 0.1MPa. The density data were utilized to evaluate standard partial molar volumes (φ0V) and partial molar isobaric expansibility (φ0E). The viscosity data were used to evaluate A-and B-coefficients, free energy of activation of viscous flow (⊿μ0*1) and (⊿μ0*2), per mole of solvent and solute respectively, enthalpy (⊿H*) and entropy (⊿S*) of activation of viscous flow. The results obtained were utilized in the qualitative elucidation of the Pro-surfactant/formamide and Pro-Pro interactions in the present systems.