Viscosities and Densities for the 1-Propanol + n-Heptane System at Several Temperatures

Viscosities and densities have been measured for 1-propanol + n-heptane at 20, 25, 30, and 35°C and atmospheric pressure. Kinematic viscosities were determined using a capillary viscosimeter; densities were measured using vibrating-tube densimetry. The viscosity deviations were evaluated. Viscosity results were fitted to the equations of Grunberg–Nissan, McAllister, Auslander, and Teja. The experimental excess molar volumes were compared with the results obtained with the Nitta–Chao model.     

The static dielectric constant of solutions of water inn-alcohols at 15, 25, 35, and 45°C

Dielectric constants (measured at 1 MHz) are reported for solutions of water (concentration range 0 to 0.2 mole fraction) in 1-propanol at 25°C, and in 1-butanol, 1-pentanol, and 1-hexanol at 15, 25, 35, and 45°C. These results, together with literature values for solutions of water in methanol, ethanol, 1-heptanol, and 1-octanol, show that water interacts with alcohols in at least two ways: (1) it can participate in the formation of dynamic hydrogen-bonded chains, thereby raising the polarizability; (2) it can form relatively stable structures such as H₂O(ROH)₄ which have zero net dipole moment and consequently diminish volume polarizability. For C _n H _2n+1 OH alcohols,n≥4, most of the initially added water forms complexes: consequently, addition of water to these alcohols lowers the dielectric constant.     

Model systems for hydrophobic interactions: Volumes and heat capacities ofn-alkoxyethanols in water

The densities and heat capacities of the first four members of the 2-n-alkoxyethanols were measured in water over the whole mole fraction range with a flow densimeter and a flow microcalorimeter. The methoxy and n-propoxy homologs were studied at 25°C, ethoxyethanol at 19, 25, and 40C, andn-butoxyethanol at 4, 10, 25, 40, and 55°C. While methoxyethanol behaves as a fairly typical polar nonelectrolyte in water,n-butoxyethanol shows trends in the concentration dependence which resemble micellization; some pseudo-microphase transition occurs at about 0.02 mole fraction, and this transition concentration decreases with increasing temperature. There is no simple relationship between this phenomenon and the existence of a lower critical solution temperature at 49°C since the sharpness of the thermodynamic changes is maximum at the lowest temperature and at 55°C the apparent molal quantities on both sides of the two-phase region appear to fall on the same continuous curve. In the region prior to the pseudo-microphase separation the apparent and partial molal heat capacities decrease regularly but beyond approximately 0.01 mole fraction increase sharply to a maximum, suggesting some type of pre-association. The apparent molal heat capacity of water in the binary solutions is larger than the molar heat capacity of water over the whole mole fraction range. The present data seem to be consistent with a clathrate model for hydrophobic hydration and interactions with these systems.     

Excess molar volumes and excess viscosities for then-hexane+dichloromethane+tetrahydrofuran ternary system at 25°C

Exces molar volumes, and excess viscosities of then-hexane+dichloromethane+tetrahydrofuran system have been determined at 25°C by measuring densities and viscosities. Different expressions exist in the literature to predict these excess properties from binary data. The empirical correlation of Cibulka is shown to be the best in this system.     

Phasengleichgewichte und Stoffwerte im System 1,2-Dichlorethan/n-Propanol/Wasser

Liquid-liquid equilibria of the ternary system 1,2-dichloroethane/n-propanol/water were measured at 20, 30, and 40 °C. In the plot of the system for 20 °C are shown the results of titration (i. e. addition of increasing quantities of water resp. 1,2-dichloroethane to the homogenous mixture of the other components). These results geree well with the plot of extraction results.The binary homogeneous systemsn-propanol/water andn-propanol/1,2-dichloroethane exhibit an non-ideal behaviour. Vapor-liquid equil. of these systems were measures at 133.32 and 666.6 mbar (100 and 500 Torr). The azeotropic points at these pressures are in good agreement with the literature.In addition to this, measurements of the values of surface-tension, viscosity and refractive index were performed.Aqueous solutions ofn-propanol can be determined by the micromethod ofR. Fischer.

Unserem Lehrer, Herrn Universitätsprofessor Dr. et Mr.Robert Fischer zum 75. Geburtstag in Dankbarkeit und Verehrung gewidmet.Die Programme wurden auf der Rechenanlage UNIVAC 494 des Forschungszentrums Graz erstellt.     

Adsorption of n-Butanol on Pb–Ga in Aqueous Solutions: Effect of Metal on the Adsorption of Organic Compounds in the Absence of Metal–Water Chemisorption Interaction

The potential dependence of the differential capacitance is measured by an ac bridge at 420 Hz and 32°C at Pb–Ga/H₂O interface in 0.05 M Na₂SO₄ solutions containing n-butanol in different concentrations. Adsorption parameters for n-butanol are determined using a regression analysis and compared with those for Hg, Tl–Ga, and Bi–Ga. As follows from this comparison, though there is no chemisorption interaction between these metals and water, the energy of n-butanol adsorption at these metals depends on the metal nature. The Pb–Ga data fit a common correlation dependence of the electronic capacitance of different electrodes (C _m ^–1)_phys on the energy of the n-butanol molecules adsorption thereon in the absence of a metal–water chemisorption interaction. This finding evidences that the dependence of the energy parameters for the adsorption of organic compounds on the metals' electronic properties, when characterized by (C _m ^–1)_phys, is of general nature.     

Activation of low-percentage Re-Al2O3 and Tc-Al2O3 catalysts for the dehydrogenation of paraffins

The activity and selectivity of low-percentage (0.1–1 mass. %) Re-Al₂O₃ and Tc-Al₂O₃ catalysts in the dehydrogenation ofn-dodecane is shown to increase in response to an increase in the temperature of their activation in hydrogen from 500°C to 900°C. The activities of such catalysts are comparable to those of analogous alumina-platinum systems, while the selectivity of the former catalysts inn-monoolefin production is higher than that of the latter.Deceased January 7, 1991.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 484–487, March, 1993.     

Evidence of change in the molecular organization of 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid solutions with the addition of water

Physico-chemical properties of ionic liquids like density, viscosity, conductivity, surface tension and excess molar volume are strongly dependent on their concentration in aqueous solutions. 1-n-Butyl-3-methylimidazolium tetrafluoroborate/water solutions, at 25 °C, shows two clearly distinguished behaviors, corresponding to a water-rich and a salt-rich region, with distinct physico-chemical properties. It is shown that [BMIm][BF₄] exhibits surfactant properties. The results obtained are discussed in terms of the interactions between cations and anions of the ionic liquid and the water molecule. IR studies show that the addition of water modifies the organization of the ionic liquid molecules. The data collection reported is helpful for a variety of different technological applications and in particular for electrochemical applications, as capacitors, batteries and fuel cells among others.     

Conductance in isodielectric mixtures. I.n-butyronitrile with dioxane,benzene, and carbon tetrachloride

The conductance of tetrabutylammonium tetraphenylboride, picrate, nitrate, and bromide has been measured at 25°C inn-butyronitrile and in mixtures of this solvent with dioxane, benzene, and carbon tetrachloride covering the range of dielectric constants from 10–24.26. For the picrate, nitrate, and bromide, the association constants at a given dielectric constant are independent of the chemical composition of the solvent. The changes of Walden products with solvent composition, however, are different, depending on which other solvent is mixed with the butyronitrile.     

Excess Enthalpies of 2,2-Dimethylbutane + Cyclohexane + (Octane or Dodecane) at 25°C

Measurements of excess molar enthalpies at 25°C in a flow microcalorimeter,are reported for the two ternary mixtures 2,2-dimethylbutane + cyclohexane +n-octane and 2,2-dimethylbutane + cyclohexane + n-dodecane. Smoothrepresentations of the results are described and used to construct constant enthalpy contourson Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpiescan be obtained from the Flory theory using only the physical properties of thecomponents and their binary mixtures.     

Allylic lithiation of methylenecyclobutanes

Methylenecyclobutanes undergo a lithiation reaction in the presence of n-BuLi or n-BuLi/KO^tBu from −78 °C to room temperature or to 40 °C in THF within 3 h and then quenching with a variety of electrophiles to give the corresponding addition products (alcohols) in moderate to good yields within 2 h. The alcohols can be easily oxidized to the ketones, which can be transformed to the substituted cyclopentenes in the presence of AlCl₃ within short reaction time.     

Viscosities of n-Alkyl Chlorides from 15 to 80°C

The viscosities of n-alkyl chlorides from pentyl to hexadecyl chloride were determined at temperatures between 15 to 80°C at 5°C intervals. The intrinsic volumes of the n-alkyl chlorides were determined by extrapolation of the plot of fluidity against molar volume to zero fluidity. Plots of the logarithm of viscosity vs. reciprocal absolute temperature were almost linear. The energies of activation for viscous flow for the n-alkyl chlorides were calculated and found to increase with increase in chain length. The fluidities, , of the n-alkyl chlorides were found to obey the modified form of Hildebrand's equation. = D[(V-V_o/V_o]\exp(-E_B/RT) where D is a constant, V and V _o are the molar volume and the intrinsic molar volume, respectively, and E _B is an energy term corresponding to the energy required for disrupting the association of the molecules. The activation energy for viscous flow consists of the sum of the energy required for the expansion of the void volume and the energy required to overcome intermolecular interactions. These energies were calculated and discussed.     

Direct and stepwise intercalation of alkylalcohols intoα-zirconium phosphate

Intercalation of alkylalcohols into -zirconium phosphate was investigated at 25°C and/or under reflux.n-Alcohols having two to five carbons and 2-propanol were taken up at 25°C. These alcohols, andn-hexanol and heptanol, also intercalated under reflux.n-Alcohols having eight to eighteen carbon atoms intercalated when a stepwise method was employed. 2-Butanol and tertiary amylalcohols intercalated under reflux using a butanol intercalate as a starting material. Ethanol-to-butanol intercalates were unstable at room temperature, losing alcohols and changing to -zirconium phosphate. The particle size of the -zirconium phosphate did not affect the intercalation of alcohols.     

Concentration Dependence of Thermoelectric Power in Aqueous Tetra-n-Butylammonium Hydroxide Using Hydrogen Electrodes

Using a hydrogen-electrode thermocell with a temperature difference of 8 K, initialthermoelectric power _in has been determined in aqueous tetra-n-butylammoniumhydroxide solutions for concentrations ranging from 0.001 to 0.2 molal at meantemperatures of 25 and 35°C. Graphs of a function of _in vs. m ^1/2/(1 + m ^1/2) yieldintercepts and infinite-dilution limiting slopes as m ^1/2 0. Using the value = 68.8±0.3 J-K^–1for the standard transported entropy of the hydroxideion, values for the enthalpy of transport of tetra-n-butylammonium hydroxide atinfinite dilution were determined to be 36.5±1.5 kJ-mol^–1 at25° and 37.7±2.0kJ-mol^–1 at 35°C.     

Volumes of mixing 2,4-dimethylpyridine withn-alkanes

In continuation of our work on excess thermodynamic properties of non-electrolyte solutions containing pyridine bases withn-alkanes, we have determined excess molar volumesV ^E for 2,4-dimethylpyridine + C₆ to C₁₀ n-alkanes at 25°C. For the investigated systems noV ^E values were available in the literature for comparison with our data. The experimentalV ^E was used to test the Prigogine-Flory-Patterson theory (PFP), Extended Real Associated Solutions model (ERAS) and the Treszczanowicz-Benson method (TB).     

Preparation of α,n-dilithiotoluene equivalents. Synthesis of tamoxifen

The successive reaction of chlorobenzyl alcohols with n-butyllithium and lithium powder in the presence of a substoichiometric amount of 4,4′-di-tert-butylbiphenyl (DTBB) at −78°C yields the expected (lithiooxymethyl)phenyllithium derivative, which is trapped by reaction with different ketones. The subsequent arene-catalysed lithiation at 25°C permits the one-pot chemoselective lithiation of the primary benzyl alcoholate in the presence of a tertiary one. These new functionalised benzyllithium derivatives react with different electrophilic compounds, such as aldehydes, ketones and chlorotrimethylsilane, to give after hydrolysis the expected functionalised benzyl alcohols. Some of these alcohols are successfully transformed into mono- or di-olefins by acidic treatment. This whole strategy is applied to the preparation of anti-cancer drug tamoxifen.     

Excess Enthalpies of 2-Methyltetrahydrofuran + 2,2,4-Trimethylpentane + (Decane or Dodecane) at 25°C

Measurements of excess molar enthalpies at 25°C in a flow microcalorimeter, are reported for the two ternary mixtures 2-methyltetrahydrofuran + 2,2,4-trimethylpentane + n-decane and 2-methyltetrahydrofuran + 2,2,4-trimethylpentane + n-dodecane. Smooth representations of the results are described and used to construct constant-enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann–Fried model using only the physical properties of the components and their binary mixtures.     

A small-angle neutron scattering study of the ethyl (n-octyl) phosphate micelles in water

Summary Mixed-double chain anionic surfactants, barium- and lithium-salts of ethyl(n-octyl) phosphate (EOP), which are asymmetric in the molecular shape, and a series of identical chain di-n-alkyl phosphate lithium salts have been synthezized. The limiting partial molar volume of a PO ₄ ^– group (23.43±0.41 cm³ mol^–1) for use in small-angle neutron scattering analysis was determined by density measurements of a series of identical chain di-n-alkyl phosphate lithium salts. For lithium EOP-D₂O system, a critical micellar concentration (2.3 wt%) was determined by³¹P NMR spectra. The micellar shape and size in the EOP-water binary system has been investigated by using small-angle neutron scattering (SANS) spectra. It has been found that the micelles of barium EOP in water have the shape of a prolate spheroid and aggregation numbers (n) equal to 48 at 23°C and 52 at 50°C. For the lithium EOP-micellar system, it has been found that the minimum micelle with an aggregation numbern=21 is spherical and micellar growth and variation from the spherical to the prolate shape might occur with an increase in concen tration above the CMC.     

Standard molar enthalpies,volumes, and heat capacities of adamantane in cyclohexane,n-hexane,and carbon tetrachloride. Interpretation using the scaled-particle theory

The volumes, heat capacities, and enthalpies of solution of adamantane in cycloxane,n-hexane, and carbon tetrachloride have been measured as a function of concentration at 25°C (15, 25, and 35°C for the volumes). The results extrapolated to infinite dilution have been resolved into cavity formation and interaction terms. The former have been calculated from the equations of the scaled-particle theory. To estimate the contribution from the latter, we have assumed some proportionality between adamantane-solvent and cyclohexane-solvent interactions. This assumption has been verified with the three different solvents for the three studied thermodynamic functions. The diameter of adamantane in solution has been determined to be 6.36 Å.     

Excess Enthalpies of Ternary Mixtures: (2-Methyltetrahydrofuran or Di-n-Butyl ether) + 3-Methylpentane + n-Decane at 25°C

Measurements of excess molar enthalpies at 25°C in a flow microcalorimeter are reported for the two ternary mixtures 2-methyltetrahydrofuran + 3-methylpentane + n-decane and di-n-butyl ether + 3-methylpentane + n-decane. Smooth representations of the results are described and used to construct constant-enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann–Fried model using only the physical properties of the components and their binary mixtures.