Solubility Of Alkanes Research Articles

Mild homogeneous oxidation and hydrocarboxylation of cycloalkanes catalyzed by novel dicopper(II) aminoalcohol-driven cores

N-benzylethanolamine (Hbea) and triisopropanolamine (H3tipa) were applied as unexplored aminoalcohol N,O-building blocks for the self-assembly generation of two novel dicopper(II) compounds, [Cu2(μ-bea)2(Hbea)2](NO3)2 (1) and [Cu2(H3tipa)2(μ-pma)]·7H2O (2) {H4pma=pyromellitic acid}. These were isolated as stable and aqua-soluble microcrystalline products and were fully characterized by IR spectroscopy, ESI–MS(±), and single-crystal X-ray diffraction, the latter revealing distinct Cu2 cores containing the five-coordinate copper(II) centers with the {CuN2O3} or {CuNO4} environments. Compounds 1 and 2 were used as homogeneous catalysts for the mild oxidation of C5–C8 cycloalkanes to give the corresponding cyclic alcohols and ketones in up to 23% overall yields based on cycloalkane. The reactions proceed in aqueous acetonitrile medium at 50°C using H2O2 as an oxidant. The effects of different reaction conditions were studied, including the type and loading of catalyst, amount and kind of acid promoter, and water concentration. Despite the fact that different acids (HNO3, H2SO4, HCl, or CF3COOH) promote the oxidation of alkanes, the reaction is exceptionally fast in the presence of a catalytic amount of HCl, resulting in the TOF values of up to 430h−1. Although water typically strongly inhibits alkane oxidations due to the reduction of H2O2 concentration and lowering of the alkane solubility, in the systems comprising 1 and 2 we observed a significant growth (up to 5-fold) of an initial reaction rate in the cyclohexane oxidation on increasing the amount of H2O in the reaction mixture. The bond-, regio- and stereo-selectivity parameters were investigated in oxidation of different linear, branched, and cyclic alkane substrates. Both compounds 1 and 2 also catalyze the hydrocarboxylation of C5–C8 cycloalkanes, by CO, K2S2O8, and H2O in a water/acetonitrile medium at 60°C, to give the corresponding cycloalkanecarboxylic acids in up to 38% yields based on cycloalkanes.

Liquid-liquid equilibria of binary mixtures of a lipidic ionic liquid with hydrocarbons.

Although structurally diverse, many ionic liquids (ILs) are polar in nature due to the strong coulombic forces inherent in ionic compounds. However, the overall polarity of the IL can be tuned by incorporating significant nonpolar content into one or more of the constituent ions. In this work, the binary liquid-liquid equilibria of one such IL, 1-methyl-3-(Z-octadec-9-enyl)imidazolium bistriflimide, with several hydrocarbons (n-hexane, n-octane, n-decane, cyclohexane, methylcyclohexane, 1-octene) is measured over the temperature range 0-70 °C at ambient pressure using a combination of cloud point and gravimetric techniques. The phase behavior of the systems are similar in that they exhibit two phases: one that is 60-90 mole% hydrocarbon and a second phase that is nearly pure hydrocarbon. Each phase exhibits a weak dependence of composition on temperature (steep curve) above ∼10 °C, likely due to swelling and restructuring of the nonpolar nano-domains of the IL being limited by energetically unfavorable restructuring in the polar nano-domains. The solubility of the n-alkanes decreases with increasing size (molar volume), a trend that continues for the cyclic alkanes, for which upper critical solution temperatures are observed below 70 °C. 1-Octene is found to be more soluble than n-octane, attributable to a combination of its lower molar volume and slightly higher polarity. The COSMO-RS model is used to predict the T-x'-x'' diagrams and gives good qualitative agreement of the observed trends. This work presents the highest known solubility of n-alkanes in an IL to date and tuning the structure of the ionic liquid to maximize the size/shape trends observed may provide the basis for enhanced separations of nonpolar species.

Phase Behavior Modeling of Bitumen and Light Normal Alkanes and CO2 by PR-EOS and CPA-EOS

The Peng–Robinson (PR) and cubic-plus-association (CPA) equations of state are used to predict the phase behavior and solubility of CO2 and normal alkanes from C1 to nC10 in several bitumens. Both of the equations of state are investigated over wide ranges of temperature and pressure. The results show that the PR-EOS describes mixure of bitumens with CO2 and alkanes when there is no second liquid phase or when the asphaltene content in the second liquid phase is not high. The CPA-EOS describes the phase behavior of mixtures of bitumens and CO2 and alkanes in liquid–liquid states even when the asphaltene content of one of the phases is high. High asphaltene content results in significant association and cross-association where the CPA-EOS is a natural choice. In this work the only adjustable parameter in the CPA-EOS is the cross-association energy parameter, and we show that the solubility of CO2 and alkanes in bitumens is usually not sensitive to this parameter. However, in two-phase liquid–liquid and thr...

Novel liquid–liquid equilibrium data for six ternary systems containing IL, hydrocarbon and thiophene at 25 °C

Ionic Liquids (IL's) are now considered as useful alternative solvent for the desulfurization of gasoline and diesel oils by liquid–liquid extraction. In this work, 1-hexyl-3-methylimidazolium thiocyanate([Hmim][SCN]) and 1-octyl-3-methylimidazolium thiocyanate([Omim][SCN]) as ionic liquids were investigated as model solvents for removal of thiophene from some aliphatic hydrocarbons (n-hexane, n-octane and n-decane) as fuel model. Liquid–liquid phase equilibrium data were measured for ternary systems containing one ionic liquid as solvent, thiophene as sulfur component and one aliphatic hydrocarbon as fuel model at 298.15 K under ambient pressure. It was found that the IL with lower molecular weight of cation has higher selectivity but lower solute distribution coefficients. Besides, the experimental data demonstrates that the selectivity increases as alkane chain length of fuel model increases while the solubility of ionic liquids decreases, hence the costs of desulfurization process will be decreased. Our results show that for the case of [Hmim][SCN](1) + n-decane(2) + thiophene(3) the highest selectivity and lowest alkane solubility were obtained. In other words [Hmim][SCN] is a more suitable solvent than [Omim][SCN] for desulfurization of higher alkane. Finally in order to find the model parameters, the nonrandom two liquid (NRTL) was used to correlate the experimental data. The results show the model can successfully correlate the experimental data.

Isolating the non-polar contributions to the intermolecular potential for water-alkane interactions.

Intermolecular potential models for water and alkanes describe pure component properties fairly well, but fail to reproduce properties of water-alkane mixtures. Understanding interactions between water and non-polar molecules like alkanes is important not only for the hydrocarbon industry but has implications to biological processes as well. Although non-polar solutes in water have been widely studied, much less work has focused on water in non-polar solvents. In this study we calculate the solubility of water in different alkanes (methane to dodecane) at ambient conditions where the water content in alkanes is very low so that the non-polar water-alkane interactions determine solubility. Only the alkane-rich phase is simulated since the fugacity of water in the water rich phase is calculated from an accurate equation of state. Using the SPC/E model for water and TraPPE model for alkanes along with Lorentz-Berthelot mixing rules for the cross parameters produces a water solubility that is an order of magnitude lower than the experimental value. It is found that an effective water Lennard-Jones energy ε(W)/k = 220 K is required to match the experimental water solubility in TraPPE alkanes. This number is much higher than used in most simulation water models (SPC/E-ε(W)/k = 78.2 K). It is surprising that the interaction energy obtained here is also higher than the water-alkane interaction energy predicted by studies on solubility of alkanes in water. The reason for this high water-alkane interaction energy is not completely understood. Some factors that might contribute to the large interaction energy, such as polarizability of alkanes, octupole moment of methane, and clustering of water at low concentrations in alkanes, are examined. It is found that, though important, these factors do not completely explain the anomalously strong attraction between alkanes and water observed experimentally.

Using Polyisobutylene as a Non-Fluorinated Binder for Coated Lithium Powder (CLiP) Electrodes

Binder formulations based on N-methylpyrrolidone/polyvinylidene fluoride (NMP/PVdF) or water/carboxymethyl cellulose (H2O/CMC) are state of the art in the fabrication of anodes for lithium-ion battery (LIB) applications. However, in combination with metallic lithium these materials tend to degrade. Therefore, for the production and operation of anodes employing metallic lithium particles another binder system, which is flexible, chemically and electrochemically inert, inexpensive, commercially available and, especially for industrial applications, usable within a broad temperature range, is needed. Polyisobutylene (PIB) is able to fulfil these criteria. The advantages of this binder are its inert structure and its solubility in alkanes (e.g. heptane), which are inert against lithium metal, as well. In this work we will introduce heptane/PIB as a binder formulation for the preparation of electrodes from coated lithium powder (CLiP) particles. We demonstrate that CLiP electrodes fabricated with this binder system exhibit better electrochemical performance than electrodes made with NMP/PVdF or tetrahydrofuran (THF)/PVdF formulations. Furthermore, CLiP immersed in heptane/PIB show also better thermal stability compared to CLiP immersed in NMP/PVdF and THF/PVdF.

Lipid Membranes as Solvent for Carbon Nanoparticles

C60 fullerene has a wide variety of applications, from nanomedicine to energy production. Most of these applications require fullerene to be dissolved, at one point. However, dissolving fullerene is difficult because of its low solubility in most common solvents, including apolar ones like alkanes. Despite low solubility in alkanes, fullerene has been shown to permeate and spread in lipid bilayers under certain conditions. The interior of a lipid bilayer is chemically identical to alkanes, so it is not clear why fullerene behavior in bilayers and alkanes would be different.We used molecular dynamics simulations and the MARTINI coarse-grained force field to understand the different behavior of fullerene in alkanes vs lipid bilayers. We find that the free energy of association between fullerenes in bilayers is lower than in alkanes, and the difference is due mostly to enthalpic contributions, not entropic ones. Confinement of fullerene in the bilayer thickness and alignment of the lipid chains do not contribute to fullerene dissolution in membranes. On the contrary, high solvent density and limited perturbation of solvent-solvent interactions upon solute aggregation favor fullerene dissolution in bilayers. Lipid bilayers are ubiquitous in living systems and their physical properties can easily be tuned by altering head group composition and chain length. We conclude that lipid bilayers are effective, tunable and biocompatible solvents for C60 fullerene.

The role of solvent cohesion in nonpolar solvation

Understanding hydrophobic interactions requires a molecular-level picture of how water molecules adjust to the introduction of a nonpolar solute. New insights into the latter process are derived from the observation that the Gibbs energies of solvation of the noble gases and linear alkanes by a wide range of solvents, including water, correlate well with linear combinations of internal pressure (Pi) and cohesive energy density (ced) of the solvent. Pi and ced are empirical solvent parameters that quantify two different aspects of solvent cohesion: the former reflects the cost of creating a cavity by a subtle rearrangement of solvent molecules, whereas the latter captures the cost of creating a cavity with complete disruption of solvent–solvent interactions. For the solvation of smaller solutes the internal pressure is the dominant parameter, while for larger solutes the ced becomes more important. The intriguing observation that the solubility of alkanes in water decreases with increasing chain length, whereas the solubility of noble gases increases with increasing size, can be understood by considering the different relative influences of the ced and Pi on the solvation processes of both classes of compounds. Also the solvation enthalpy, but not the entropy, correlates with linear combinations of solvent ced and Pi, albeit poorly, suggesting that the good correlations observed for the Gibbs energy are largely due to enthalpy, most likely that related to cavity formation.

Sorption of hydrocarbons and alcohols in addition-type poly(trimethyl silyl norbornene) and other high free volume glassy polymers. II: NELF model predictions

Abstract Sorption and swelling of alkane and alcohol vapors in addition-type poly(trimethyl silyl norbornene) (PTMSN) obtained in part I of this work were analyzed and compared to the predictions of the Non-Equilibrium Lattice Fluid (NELF) model. The polymer characteristic Lattice Fluid (LF) parameters were determined by best fitting the infinite dilution solubility coefficients, S0, of a wide series of n-alkane penetrants, from ethane to n-dodecane. The solubility of alkanes, which is comparable quantitatively and qualitatively to that measured in PTMSP, is well represented by the model. The solubility isotherms of alcohols (methanol, ethanol and 1-propanol), which exhibit a peculiar sigmoidal behavior that finds no explanation within the dual mode model, are also in line with the NELF model prediction without any ad hoc correction. The model is also used to represent successfully the dependence of the solubility on the alkane size, in PTMSN as well as in PTMSP and Teflon AF2400. The three polymers exhibit different trends: in PTMSP the vapor-pressure normalized solubility coefficient (S0 pvap) increases with the penetrant size, while in Teflon AF2400 the behavior is opposite and in PTMSN the size plays a very little role on the activity-based solubility. Such a behavior, that is useful to determine the selective performance of the polymer, was analyzed and discussed taking advantage of the support offered by the NELF model: it was seen that the three main factors affecting the extent of solubility dependence on the alkane size are the polymer fractional free volume and cohesive energy density, as well as its energetic interaction with the penetrant; an approximate formula is used to estimate a priori the behavior of the solubility based on the knowledge of the polymer properties.

Determination of the thermodynamics of the methyl group in solutions of drug molecules.

Abstract The contribution of the CH3 group to the solution thermodynamics of drug molecules is dependent on whether it is attached to a ring system or is in the terminal position in an aliphatic chain. In the former case group contributions for CH3 are very similar to those found for the CH2 group. For instance, in partition, the CH3 group contribution (log Fch3) is in the range 0.65 to 0.28 (ΔG = 2.303 RT log Fch3) and is dependent on the polarity of the organic solvent. The contribution for the terminal aliphatic CH3 is not equivalent to the mid chain CH2 and a CH3 correction factor or 1.14 to 1.34 kcalmol−1 (4.77 to 5.61 kJmol−1), has been calculated from alkane solubility data and partition studies. The additivity of group contributions and the correct choice of reference state are also discussed.

Phase Behavior Modeling of Alkyl−Amine + Water Mixtures and Prediction of Alkane Solubilities in Alkanolamine Aqueous Solutions with Group Contribution with Association Equation of State

Precise knowledge of phase behavior of natural gas + aqueous alkanolamine solutions is of interest to design and optimize amine absorption units. In this work, we extend a group contribution with association equation of state to the modeling of phase behavior of mixtures containing water, alkanolamine, and light hydrocarbons (HC). The model parameters were estimated on the basis of binary vapor−liquid equilibrium and liquid−liquid equilibrium data of the following binary systems: HC + amines, HC + alcohol, water + amine, water + alcohol. The group contribution approach allows the use of an extended databank of experimental data which gives a solid foundation for predicting hydrocarbon solubility in aqueous alkanolamine solutions.

Solubility of alkanes, alkanols and their fluorinated counterparts in tetraalkylphosphonium ionic liquids

We investigated the mutual solubility of mixtures of phosphonium-based ionic liquids with alkanes, alkanols, fluorinated alkanes and fluorinated alkanols. The solubilities of other solute molecules like water, formamide, 1,4-dioxane, benzene, and dimethylsulfoxide were also tested. Whenever possible, the corresponding temperature-composition (T-x) phase diagrams at atmospheric pressure were built from cloud-point temperature determinations. The influence of the size of the solute was tested with binary mixtures of trihexyl(tetradecyl)phosphonium acetate, [P(6 6 6 14)][Ac], with hexane, decane or tetradecane. The influence of the anion of the ionic liquid, namely acetate, [Ac], bis-[(trifluoromethyl)sulfonyl]imide, [Ntf(2)], trifluoromethanesulfonate, [Otf], and dicyanamide, [dca], on the solubility of the ionic liquids in hexane was also studied. For the ionic liquid [P(6 6 6 14)][Ntf(2)] the liquid-liquid phase diagrams were determined with different solutes-alkanes, perfluoroalkanes, partially fluorinated alkanes, and partially fluorinated alkanols-with the aim of analysing the solute-solvent interactions. A comparison of the phase behaviour of solutions containing phosphonium-based ionic liquids and 1-alkyl-3-methylimidazolium based ionic liquids, including a discussion of their different morphologies at a structural level, is also provided. It was found that fluorination of the aliphatic chains of organic compounds can be used as an effective way to control the solubility limits of these compounds in phosphonium- or imidazolium-based ionic liquids, both in terms of concentration and temperature.

Kinetic Isotope Effects on the Photolysis of C60H18 and C60D18

Fullerane C60H18 and its deuterated analogous C60D18 were synthesized in n‐hexane solution by a reduction reaction of C60 under the action of HCl or DCl on Zn dust. The resulting solutions were subjected to UV irradiation at 245 nm from a low pressure mercury lamp under He. It was found that at 212 nm the photolysis rate constant of C60H18 molecule Hk212 = 8.68 × 10−4 s−1 was significantly higher than that of its deuterated analogous C60D18: Dk212 = 5.93 × 10−4 s−1. Similarly, at 256 nm it was confirmed the result that C60D18 was photolyzed more slowly than C60H18. Also in this case, Hk256 = 6.83 × 10−4 s−1 is significantly higher than that of its deuterated analogous C60D18: Dk212 = 3.74 × 10−4 s−1. Kinetic isotope effect involving the C‐H and C‐D bond activation has been advocated to explain the differences in photodecomposition speed of C60H18 in comparison to C60D18. On the basis of solubility in alkanes and unique electronic absorption spectrum C60H18 with C3ν symmetry prepared under high hydrogen pressure can be easily distinguished from the C60H18 and its deuterated analogous C60D18 synthesized in n‐hexane from Zn/HCl or Zn/DCl. The C3ν ‐ C60H18 displayed also a different evolution of the electronic absorption spectrum under photolysis in comparison to C60H18 and its deuterated analogous C60D18. The pseudofirst rate constant of C3ν ‐C60H18 is k217 = 4.04 × 10−4 s−1 and k255 = 2.25 × 10−4 s−1.

Simple Correlation Accurately Predicts Aqueous Solubility of Light Alkanes

The solubility of hydrocarbon components in water is of great importance for the environmental sciences. Its prediction is usually based on using the pure component solubilities and the mole fraction of the components in the mixture. The solubility of light alkanes (methane and ethane) in pure water has been studied extensively in past decades. However, due to their extremely low solubilities, it is necessary to predict the aqueous solubility of those components using an accurate method. This article presents a simple-to-use correlation for better prediction of aqueous solubility of light alkanes, where the obtained results of the proposed method have been compared with two activity coefficient models (NRTL and UNIQUAC) and showed good agreements with the observed values.

New model calculates solubility of light Alkanes in triethylene gycol

New model, which cover the full range of dehydration-plant operating conditions and wide range of experimental data results, estimate the amount of CH4, C2H6 and C3H8 absorbed per volume of triethylene glycol (TEG) circulated vs. the reduced partial pressure of light Alkanes and the absorber reduced temperature. TEG has a tendency to remove the hydrocarbons. Hydrocarbon solubility is a major factor when considering the use of a physical solvent. Quantifying this amount of absorption is critical in order to minimize hydrocarbon losses or to optimize hydrocarbon recovery. This article provides comparisons with experimental data.

Simplified Method for Calculating Solubilities of Hydrocarbons in Hydrate Inhibitors

AbstractSignificant amount of work has been performed in order to determine the solubility of light hydrocarbons (methane and ethane) in the most commonly used hydrate inhibitors (such as methanol and ethylene glycol) at various temperatures and pressures. These solubility data have been compiled and correlated. In most cases, however, current models may not be sufficient if accurate predictions are needed. The aim of this study is to present a simple‐to‐use method for accurate prediction of solubilities of light hydrocarbons in methanol and ethylene glycol (at different weight percentages in water) as a function of reduced partial pressure and reduced temperature. The predictions from the method proposed are compared with reported experimental data and found good agreement between observed data and the predicted values with average absolute deviation less than 1.46 %. It was also found that this method is more accurate than conventional thermodynamical approaches (in particular, the NRTL model) in predicting the solubilities of light alkanes in hydrate inhibitors.

Solubility of alkanes in a polystyrene matrix

AbstractThe solubilities of seven alkanes in a matrix of uncrosslinked polystyrene were measured at several different temperatures. A gravimetric method reported earlier was used to monitor the sorption of the solvents. The experimental measurements showed unambiguously that the solubility of the alkanes diffusing into a polystyrene matrix reached a constant and reproducible value typical for each system and temperature. These values could be interpreted very well with the Flory–Huggins solubility parameter (χ = a(entropic contribution to x) + b(enthalpic contribution to x)/T[absolute temperature in Kelvin (K)]) or with the van't Hoff equation (ln KS = ΔS/R(gas constant) − ΔH/RT, where KS is the equilibrium constant, ΔS is the entropy change, and ΔH is the enthalpy change). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Analyzing solubility of acid gas and light alkanes in triethylene glycol

Physical solvents such as ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) are com- monly used in wet gas dehydration processes with TEG being the most popular due to ease of regeneration and low solvent losses. Unfortunately, TEG absorbs significantly more hydrocarbons and acid gases than EG or DEG. Quantifying this amount of absorption is therefore critical in order to minimize hydrocarbon losses or to optimize hydrocarbon recovery depending on the objective of the process. In this article, a new correlation that fully covers the operating ranges of TEG dehydration units is developed in order to determine the solubility of light alkanes and acid gases in TEG solvent. The influence of several parameters on hydrocarbon and acid gas solubility including temperature, pressure, and solvent content is also examined.

New numerical model for solubility of light alkanes in triethylene glycol

New numerical model for solubility of light alkanes in triethylene glycol

Analysis of Polymeric Methylaluminoxane (MAO) via Small Angle Neutron Scattering

Since its discovery as a crucial cocatalyst in metallocene and post-metallocene olefin polymerizations methylaluminoxane (MAO) has retained commercial and academic status. In spite of continued interest the MAO structure remains ambiguously defined. Because of limited alkane solubility toluene emerged as the MAO solvent of necessity. With time these toluene solutions can develop a gel fraction. The MAO structures proposed include linear, ring, ladder, and cyclic with the latter involving fused four and six membered rings along with cage and drumlike architectures. The linear and ring structures have aluminum and oxygen valences of three and two respectively while the other structures require Al/O co-ordination numbers of four and three. MAO structural information has been gathered from colligative property measurements, various NMR formats and quantum chemical calculations. We have used small-angle neutron scattering (SANS)fortified with static and dynamic light scattering (SLS/DLS)as the primary analysis...