Solubility of pentane, 2-methylbutane,and cyclopentane in liquid nitrogen at 77.4 K

The solubilities of pentane, 2-methylbutane (isopentane) and cyclopentane were measured in liquid nitrogen at 77.4 K by the filtration method. The solubilities of the C₅ hydrocarbons in liquid nitrogen at 77.4 K vary from 1.8×10^–8 mole fraction for cyclopentane, to 3.0×10^–8 mole fraction for pentane and 3.2×10^–7 mole fraction for 2-metylbutane. Correlations between the solubilities of alkanes, alkenes and cyclic hydrocarbons in liquid nitrogen, and some properties of solutes [normal boiling point T _b , enthalpy of vaporization at normal boiling point H _b and the mean of the enthalpy of vaporization and the enthalpy of melting [(H _b +H _m )/2] are presented.     

Solubility of Solid Hexane and Cyclohexane in Liquid Argon at 87.3 K

The solubilities of solid hexane and cyclohexane in liquid argon at 87.3 K have been measured by the filtration method. The hexane and cyclohexane content in solution was determined using gas chromatography. The solubilities of the C₆ hydrocarbons in liquid argon at 87.3 K are (0.56 ± 0.11) × 10^-7 mole fraction for hexane and (1.04 ± 0.30) × 10^-7 mole fraction for cyclohexane. The Preston–Prausnitz method was used for calculation of the solubilities of solid hexane and cyclohexane in liquid argon in the temperature range 84–110 K. The values of the solvent–solute interaction constant l₁₂ were also calculated.     

Solubility of Solid 2,3-Dimethylbutane and Cyclopentane in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubilities of solid 2,3-dimethylbutane and cyclopentene in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in solutes. The experimental value of the mole fraction solubility of solid 2,3-dimethyl-butane in liquid argon at 87.3 K is (8.26 ± 1.60) × 10^–6 and (2.77 ± 0.94) × 10^–8 in liquid nitrogen at 77.4 K. The experimental value of the mole fraction solubility of solid cyclopentene in liquid argon at 87.3 K is (5.11 ± 0.44) × 10^–6 and (4.60 ± 0.76) × 10^–8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbons in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l ₁₂ were also calculated. At 90.0 K liquid argon is a better solvent for investigated solid hydrocarbons than is liquid nitrogen.     

Solubility of Solid 2-Methyl-1,3-butadiene (Isoprene) in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubility of solid 2-methyl-1,3-butadiene (isoprene) in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K has been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in the solute. The experimental value of the mole fraction solubility of solid isoprene in liquid argon at 87.3 K is (1.41 ± 0.27) × 10^–6 and (1.56 ± 0.36) × 10^–7 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbon in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l ₁₂ were also calculated. At 90.0 K liquid argon is a better solvent for isoprene than is liquid nitrogen. The experimental values of the solubilities of isoprene in liquid argon and nitrogen were compared with results obtained for selected unsaturated and aromatic hydrocarbons.     

Solubility of Solid 1-Hexyne in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubilities of solid 1-hexyne in liquid argon at 87.3 and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in 1-hexyne. The experimental value of the mole fraction solubility of solid 1-hexyne in liquid argon at 87.3 K is (0.85 ± 0.19) × 10^–7 and (1.25 ± 0.08) × 10^–8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbon in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l ₁₂ were also calculated. At 90.0 K liquid argon is a better solvent for solid 1-hexyne than is liquid nitrogen.     

Solubility of 1-Pentene Ice in Liquid Nitrogen and Argon at the Standard Boiling Points of the Solvents

The solubilities of 1-pentene ice in liquid nitrogen at a temperature of 77.4 K and in liquid argon at 87.3 K have been measured by the filtration method. The 1-pentene content in solution was determined using gas chromatography. The experimental value of the mole fraction solubility of 1-pentene ice in liquid nitrogen at 77.4 K is: (1.28±0.25)×10^–7 and (4.11±0.44)×10^–7 in liquid argon at 87.3 K. The Preston–Prausnitz method was used for calculation of the solubilities of 1-pentene ice in liquid nitrogen in the temperature range 64.0–90.0 K and in liquid argon in the temperature range 84.0–90.0 K. The parameters l ₁₂ were also calculated. At 90.0 K liquid argon is the better solvent for 1-pentene ice than is liquid nitrogen.     

Solubility of Solid 1-Hexene and 2-Methylpentane in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubilities of solid 1-hexene and 2-methylpentane in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. The experimental value of the mole fraction solubility of solid 1-hexene in liquid argon at 87.3 K is (3.87 ± 0.74) × 10^-7 and (7.94 ± 2.47) × 10^-9 in liquid nitrogen at 77.4 K. The experimental value of the mole fraction solubility of solid 2-methylpentane in liquid argon at 87.3 K is (1.45 ± 0.36) × 10^-5 and (6.80 ± 2.16) × 10^-8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbons in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters 1₁₂ were also calculated. At 90.0 K, liquid argon is a better solvent for solid 1-hexene and 2-methylpentane than is liquid nitrogen.     

The solubilities of nitrous oxide,carbon dioxide,Aliphatic ethers and alcohols,and water in cryogenic liquids

Experimental investigations using IR spectroscopy and a variable pressure cell (up to 30 bar) have shown that nitrous oxide, carbon dioxide and some aliphatic ethers are considerably soluble in liquid nitrogen, liquid oxygen and liquid argon between 77 K and 135 K, with solubilities ranging from 10⁻⁴ mole fraction for nitrous oxide to 10⁻⁸ mole fraction for di-isopropyl ether. The solubility data have been found to be dependent on the temperature of the cryogenic liquid and the molecular structures and properties of the solute and solvent molecules. The solubilities of water, hydrogen sulphide, methanol and ethanol have been found experimentally to be very low, i.e. less than 10⁻⁸ mole fraction in liquid nitrogen, liquid oxygen and liquid argon. These values are considerably lower than those measured previously using gravimetric methods (10⁻⁷ - 10⁻⁵). The experimental solubilities are compared with the predicted values based on the “ideal” and “regular solution” theories. Both theories failed to predict solubilities comparable with the experimental values.     

Solubility of carbon dioxide,ethane, methane,oxygen, nitrogen,hydrogen, argon,and carbon monoxide in 1-butyl-3-methylimidazolium tetrafluoroborate between temperatures 283 K and 343 K and at pressures close to atmospheric

Experimental values for the solubility of carbon dioxide, ethane, methane, oxygen, nitrogen, hydrogen, argon and carbon monoxide in 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF₄] – a room temperature ionic liquid – are reported as a function of temperature between 283 K and 343 K and at pressures close to atmospheric. Carbon dioxide is the most soluble gas with mole fraction solubilities of the order of 10⁻². Ethane and methane are one order of magnitude more soluble than the other five gases that have mole fraction solubilities of the order of 10⁻⁴. Hydrogen is the less soluble of the gaseous solutes studied. From the variation of solubility, expressed as Henry’s law constants, with temperature, the partial molar thermodynamic functions of solvation such as the standard Gibbs energy, the enthalpy, and the entropy are calculated. The precision of the experimental data, considered as the average absolute deviation of the Henry’s law constants from appropriate smoothing equations is of 1%.     

Vibrational analysis of alkyl bromides: Part III. Branched-chain bromides: 1-bromo-3-methylbutane and 1-bromo-4-methylpentane

Liquid-state IR and Raman spectra and solid-state IR spectra were obtained for 1-bromo-3-methylbutane and 1-bromo-4-methylpentane. The butane exists as a mixture of P_C and P_H conformers in the liquid and amorphous solid, but only the P_H conformer is present in the crystalline solid. The pentane exists as a mixture of P_C,P_H, and P'_H conformers in the liquid and amorphous solid. The solid could not be made to crystallize. The observed bands are assigned to the appropriate conformers with the aid of normal coordinate calculations.     

Low-pressure solubilities and thermodynamics of solvation of eight gases in 1-butyl-3-methylimidazolium hexafluorophosphate

Experimental values for the solubility of carbon dioxide, ethane, methane, oxygen, nitrogen, hydrogen, argon and carbon monoxide in 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF₆] – a room temperature ionic liquid – are reported as a function of temperature between 283 and 343 K and at pressures close to atmospheric. Carbon dioxide is the most soluble and hydrogen is the least soluble of the gases studied with mole fraction solubilities of the order of 10⁻² and 10⁻⁴, respectively. All the mole fraction solubilities decrease with temperature except for hydrogen for which a maximum is observed at temperatures close to 310 K. From the variation of solubility, expressed as Henry's law constants, with temperature, the partial molar thermodynamic functions of solvation such as the standard Gibbs energy, the enthalpy, and the entropy are calculated. The precision of the experimental data, considered as the average absolute deviation of the Henry's law constants from appropriate smoothing equations, is better than ±1%.     

High-Sensitivity Determination of Hydrocarbon Impurities in Arsine by Reaction Gas Chromatography

It is shown that the results of determining methane in high-purity arsine by reaction gas chromatography can be overestimated by more than two orders of magnitude. This overestimation is caused by the formation of methane as a side product of the reaction. Cryogenic preconcentration at the injection stage is proposed to improve the accuracy of determination of methane, and the cryofocusing of impurity hydrocarbons is proposed to improve separation. Detection limits of (3–10) × 10^–6 vol % are achieved for C₁–C₅ hydrocarbons.     

Adsorption energetics of hydrocarbons on silicalite

The differential adsorption heat curves for hydrocarbons on silicalite feature Langmuir invariance without apparent interaction for heptane, a linear increase with increasing occupancy for pentane, and great complexity with both minima and maxima for benzene. The adsorption heat increment per CH₂ group is 10.0 kJ/mole from the adsorption heat data for ethane, butane, pentane, and heptane, while the free regression term corresponding to the adsorption of 2H or H ₂ is 11.5 kJ/mole. The mean molar entropies of pentane and heptane is less than the entropies of the liquids by -60 J/mole · K, while the state of normal alkanes in silicalite channels is solidlike. The isotherms for the adsorption of hydrocarbons on silicalite are described completely by the volumetricmicropore occupancy theory equations. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2333–2335, October, 1989.     

Determination of the solubility of vinyl stearate in water by a monolayer technique

Summary The surface activity of vinyl stearate has provided a method for determining its solubility in water to be 0,7±0,2×10^–6 mole/litre. The methods described above could be used to determine the solubility in water of any sparingly soluble surface active compound, such as stearic acid or cetyl alcohol, which formed a stable monolayer at theA/W interface. Method A could be used for compounds with a solubility as low as 10^–5 mole/litre where as for Method B solubilities as low as 10^–7 mole/litre could be measured.     

The state of dissolved benzene in aqueous solution

Henry's law constants for benzene in water have been measured by bringing water layers into equilibrium with solutions of benzene in carbon tetrachloride or in cyclohexane. The mole fraction of benzene in the aqueous layer was determined by ultraviolet absorption spectrophotometry, and its fugacity was taken as equal to that in the nonaqueous phase, reliable data for the C₆H₆–CCl₄ and C₆H₆–c–C₆H₁₂ systems being available in the literature. Measurements were made at 5^o intervals from 10 to 30°C inclusive, at mole fractions down to from 10% to 20% of saturation. In no case did Henry's law constant depart significantly from constancy, and it was in reasonable agreement with some representative literature values based on saturated solubility. The constancy and the magnitudes of our K_h values indicate that appreciable dimerization does not occur in the temperature range examined here. This conclusion contrasts with the suggestion of Reid, Quickenden, and Franks that their calorimetrically measured heat of solution of benzene in water is different enough from the van't Hoff heat to imply possible dimerization of the solute; it also contrasts with the hydrophobic-bond-forming tendency which Ben-Naim, Wilf, and Yaacobi ascribe to benzene on the basis of their studies of the solubilities of benzene and biphenyl. The results of the latter study, when combined with the known second virial coefficient of benzene vapor, predict that more than 20% of the benzene in saturated aqueous solution at 25°C should be present as dimer, in clear contradiction to the results of the present work.     

Solubility of methane in aqueous solutions of triethylenediamine

The solubilities of methane were measured in water and aqueous solutions of triethylenediamine (TED), triethylenediamine hydrochloride (TED·HCl), and HCl at several concentrations up to 1M at 5° intervals from 5 to 25°C. Methane solubilities in solutions of TED·HCl and HCl are lower than those in water and decrease with increasing cosolute concentration. In contrast, the solubilities in TED solutions are greater than those in water and increase with increasing TED concentration. The order of methane solubilities at 25°C in water and in 0.5M aqueous solutions is TED>H₂O>HCl>TED·HCl with Ostwald coefficients of 3.57×10^–2, 3.44×10^–2, 3.26×10^–2, and 3.19×10^–2, respectively, and with an experimental precision of about ±0.2×10^–3. Thermodynamic functions for the transfer of methane from water to 0.25, 0.50, and 0.75M aqueous solutions have been calculated on the molar concentration scale. The free energies of transfer are compared with previous results for methane in aqueous solutions of tetraalkylammonium halides.     

Solubility of oxygen, carbon dioxide and water in semifluorinated alkanes and in perfluorooctylbromide by molecular simulation

Solubilities of oxygen, carbon dioxide and water in substituted fluorocarbons perfluoroctylethane (PFOE), perfluorohexylethane (PFHE), perfluorohexylhexane (PFHH) and perfluoroalkylbromide (PFOB) were studied by computer simulation, between 293 and 313 K at 1 bar. The solubilities do not show a marked temperature dependence, are similar in all solvents and have values of the order of 4×10⁻³ for oxygen, 2×10⁻² for carbon dioxide and 3×10⁻⁶ for water, in mole fraction. The gases are slightly less soluble in PFHE when compared with the other solvents, whereas water is slightly more soluble in this liquid. The solubilities were obtained from Henry’s law coefficients, in turn derived from residual chemical potentials of the solutes at infinite dilution obtained by molecular simulation techniques using full atomistic force fields.     

Tunable Diode Laser Absorption Studies of Hydrocarbons in RF Plasmas Containing Hexamethyldisiloxane

Tunable infrared diode laser absorption spectroscopy has been used to detect the methyl radical and three stable molecules, CH₄, C₂H₂ and C₂H₆, in radio frequency plasmas (f=13.56 MHz) containing hexamethyldisiloxane (HMDSO). The methyl radical concentration and the concentration of the stable hydrocarbons, produced in the plasma, have been measured in pure HMDSO discharges and with admixtures of Ar, while discharge power (P=20–200 W), total gas pressure (p=0.08–0.6 mbar), gas mixture and total gas flow rate (=1–10 sccm) were varied. The methyl radical concentration was found to be in the range of 10¹³ molecules cm^-3, while methane and ethane are the dominant hydrocarbons with concentrations of 10¹⁴–10¹⁵ mol cm^-3. Conversion rates to the measured stable hydrocarbons (RC(C_xH_y): 2×10¹²–2×10¹⁶ molecules J^-1 s^-1) could be estimated in dependence on power, flow, mixture and pressure. Under the used experimental conditions a maximum deposition rate of polymer layers of about 400 nm min^-1 has been found.     

Magnesium and calcium surfactants Ternary phase diagrams of magnesium and calcium dodecylsulphate with decanol and water

The isothermal ternary phase diagrams for the systems magnesium dodecylsulphate-decanol-water at 40 °C and calcium dodecylsulphate-decanol-water at 50 °C are determined by water deuteron NMR and polarizing microscopic studies. In the magnesium system, three liquid crystalline phases (lamellar and normal and reverse hexagonal) and two isotropic (normal and reverse) solution phases are characterized and their ranges of existence are obtained. The calcium system yields the same liquid crystalline phases, but only the lamellar liquid crystalline phase is investigated in detail. The important observations made are: (i) The lamellar liquid crystalline phase for the magnesium and calcium systems can incorporate, respectively, a maximum of 22.5 and 14.3 mole water per mole surfactant ion against 139 mole water for the corresponding sodium system. (ii) The reverse hexagonal liquid crystalline phase is formed for both the magnesium and calcium systems while no such liquid crystalline phase exists for the corresponding sodium system. (iii) The²H NMR quadrupole splittings obtained in the liquid crystalline phases for C₈SO ₄ ^– and C₁₂SO ₄ ^– surfactant systems with different counterions (Ca²⁺,Mg²⁺,Be²⁺,Na⁺) reveal that surfactant hydration is almost independent of alkyl chain length and counterions.     

Preconcentration of neptunium by supported liquid membranes for luminescent analysis of environmental samples

The possibilities of liquid membrane preconcentration of neptunium from environmental samples of different nature have been studied. The use the solid-supported liquid membrane containing a trioctylmethylammonium nitrate carrier allows to achieve preconcentration factors of 10²–5×10². The teflon solid support does not interact with the luminescent matrix (CaF₂, PbMoO₄) during calcination at 900 °C, so it makes practical to measure the neptunium content by luminescence without reextraction to aqueous solution. As a result, the detection limit of neptunium is lowed down to 10^–13 g ml^–1 and 5×10^–13 g g^–1 for pure solutions and soils, respectively.