Liquid−liquid equilibrium data in binary systems γ-valerolactone + hydrocarbon (n-heptane, n-decane, n-dodecane, cyclohexane, and 2,4,4-trimethyl-1-penetene) were determined by direct analytical and cloud-point methods. The experimental data were smoothed by the extended scaling law equation which respects nonclassical behavior of fluid mixtures in critical loci. The nonrandom two-liquid equation's parameters were evaluated from the data obtained, as well. Since the molecule of γ-valerolactone retains a quite high dipole moment, the acquired experimental data on liquid−liquid equilibrium were used for the testing of predictive capabilities of the perturbed-chain polar SAFT equation of state (PCP-SAFT) in comparison to the original PC-SAFT model. Vapor pressures of γ-valerolactone in the temperature range from 264 K to 313 K and its liquid densities at temperatures from 288 K to 363 K were measured and utilized for evaluation of the PCP-SAFT and PC-SAFT parameters. It was found that prediction of liquid−liquid equilibrium performed by the polar PCP-SAFT equation with pure component parameters can be classified as relatively successful. ■ INTRODUCTIONγ-Valerolactone (GVL) is a natural compound which can be found for example in fruits. Recently this compound has gained attention as a versatile sustainable liquid which can be efficiently produced from biomass, preferentially from lignocellulose. The versatility of GVL is very wide. GVL can be utilized as liquid fuel, green solvent, and food additive or as an organic intermediate in the syntheses of other chemicals. To produce GVL from biomass, different technologies are studied. A pioneering technology suggested by Horvath et. al 1 involves a high pressure hydrogenation step which is rather costly for large-scale production of GVL. Romań et al. 2 devised a less expensive method to synthesize the key biofuel component, which could make its industrial production much more costeffective. From this point of view the utilization of GVL as fuel, fuel additive, or fuel precursor seems to be very promising. GVL can be converted to lower molecular weight valerate esters (methyl-, ethyl-, and propyl valerate) suitable for use as a gasoline additive and higher esters (butyl and pentyl valerate) that could be used directly as a diesel fuel or as a diesel additive. 3 Alternatively GVL can be converted to butane molecules which can be further combined to yield longer hydrocarbon chains for diesel or jet fuels. 4 A comparison of GVL with absolute ethanol as a gasoline additive was done by Horvath et al. 5 It was found that most of the data for GVL are comparable with that of ethanol. The lower vapor pressure of GVL even leads to improved performance. According to experiments carried out by Bereczky et al., 6 the addition of GVL to diesel fuels had relatively little effect on engine performance and NO x emission, but it significantly reduced the exhaust concentration of CO, unburned fuel, and smoke. The use of GVL as direct additive to gasoline can be restricted however because of t...
A newly developed static apparatus, capable of measuring the vapor pressure in the temperature range 273–368 K and in the pressure range 0.1–1333 Pa, is presented. The apparatus was calibrated by measuring the vapor pressure of recommended reference materials, naphthalene, n-decane, and ferrocene, and thoroughly tested. Subsequently, new vapor pressure data for benzophenone were measured in the temperature range 293–365 K with the aim to establish revised thermophysical data for this compound. Although benzophenone is another material recommended as the reference material for sublimation pressure and enthalpy measurements, the published sublimation thermodynamic data show a significant spread, and the recommendation was made with reservations which involved a reported metastable crystalline phase. We clarify this point based on reviewing the literature reporting the phase behavior and crystallographic studies and an extensive study on the polymorphic behavior of benzophenone performed in the present work. These findings are put in context with the studies reporting thermodynamic properties in which the authors were not aware of polymorphic behavior of benzophenone. The experimental data on vapor pressure for benzophenone were supplemented by ideal-gas heat capacities calculated by combining statistical thermodynamics and density functional theory (DFT) calculations. Calculated ideal-gas heat capacities and critically assessed experimental data on vapor pressure, condensed phase heat capacities, and sublimation enthalpies were subsequently treated simultaneously to obtain a consistent description of vaporization and sublimation thermodynamic properties of benzophenone.
Vapor pressures of four organic iodides, 1-iodo-2-methylpropane (CAS Registry No. 513-38-2), 1-iodo-3-methylbutane (CAS Registry No. 541-28-6), 1-iodohexane (CAS Registry No. 638-45-9), and iodocyclohexane (CAS Registry No. 626-62-0), were measured using the static method in the technologically important temperature range (254 to 308) K. The experimental data were fitted with the Clarke and Glew equation. To our knowledge, this is the first time that vapor-pressure measurements for 1-iodohexane and iodocyclohexane are reported in the given temperature range. For 1-iodo-2-methylpropane and 1-iodo-3-methylbutane, the present measurements update the only available literature data originating from the year 1895.
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