Hexane, methane solubility

The complexes are very soluble in methanol, ethanol, butanol, methyl Cellosolve (2-methoxyethanol), and ethyl Cellosolve (2-ethoxyethanol), and to a fair degree, quite soluble in 1,2-dimethoxyethane and di- and triglyme. They are initially quite soluble in tetrahydrofuran, acetone, pyridine, nitro-methane, acetonitrile, dimethyl sulfoxide, and iV,A/-dimethyl-formamide, but usually precipitation of the nickel halide-solvent complex occurs if attempts are made to prepare moderately concentrated solutions in these solvents. They are only very slightly soluble, or are quite insoluble in dioxane, ethyl ether, hexane, dichloromethane, ethyl acetate, and methyl- and butyl-cellosolve acetate (2-methoxyethyl and 2-butoxyethyl acetate). 

Solubility miscible with benzene, chloroform, dichloro-methane, ether, and hexane practically insoluble in ethanol (95%) and water. 

Complex (LMe, Pr2)ScCl2(THF) is an off-white solid that is soluble in most organic solvents, such as diethyl ether, THF, hexanes (slightly), toluene, and bromoben-zene however, prolonged exposure to chlorinated solvents such as dichloro-methane or chloroform results in decomposition. Although (LMe l>,2)ScCI2(THF) rapidly decomposes upon exposure to even trace air or moisture, samples can be stored indefinitely under an inert atmosphere. 

The intramolecular parameters kf,ro, kg, and 0q from the AMBER force field [21, 22] were used. The oxygen atoms of alcohols and ethers were described by the OPLS parameters [17,18]. The Lennard-Jones parameters for halogens and the atoms of the aliphatic groups were optimized to reproduce the experimentally measured solubilities of methane and its halogenated derivatives in water and hexane, separately [23]. The resulting parameters do not follow the standard combination rules because we were unable to find a set of parameters consistent with the rules which would yield sufficiently accurate solubilities of the solutes in both phases. A similar difficulty was encountered in other studies of interfacial systems, in which the united atom representation was used to describe nonpolar molecules [24, 25]. 

All eight molecules discussed in this work are interfacially active. This does not, however, mean that all neutral solutes tend to concentrate at the interface. To illustrate this point we show in Fig. 11, the free energies of transfer, AA z), across the water-hexane and the water-GMO bilayer interfaces for two simple molecules, methane and fluoromethane [11]. Whereas fiuoromethane has a pronounced free energy minimum at the interface, AA z) characteristic of methane decreases monotonically when the solute is transferred from water to the interior of the membrane. At the water-hexane interface, the AA z) profile exhibits only a very shallow minimum, smaller than the thermal energy. Calculations of the free energy profiles for several molecules very poorly soluble in water [12,13] - perfluoroethane, 1,2-dichlorohexafluorocyclobutane, oc-tafluorocyclobutane and 2,3-dichlorooctafluorobutane... 

The knowledge of reliable thermodynamic data of saturated and aromatic hydrocarbons in water is very useful in several practical and theoretical fields, f.i. it is essential for the developments of the concepts of the hydrophobic hydration and of the hydrophobic interaction largely used for the understanding of some important biological phenomena. So new experimental data of high quality are necessary, having the elaborations of the existing material reached their limits. In the last years instead new solubility data in pure water have been reported only for methane(10,53a) ethane(53), cyclo-propane(54), n-butane(9,53a) and benzene(17). Enthalpies of hydration have been furthermore determined by direct calorimetric measurements only for benzene and some derivatives, cyclohexane, pentane and hexane(29). 

Figure 9. Pure gas propane permeability and propane/methane selectivity for a series of selected organic liquids (O), rubbery siloxane-based polymers ( ), and glassy polymers ( ). The glassy polymers include PI, a polyimide (79), PC, polycarbonate (80), PS, polystyrene (81), and PTMSP (82), Data for the siloxane-based rubber polymers are from Stem et al (83), The solubility of propane and methane in selected organic liquids (hexane, heptane, octane, acetone, benzene, methanol, and ethanol) is from the compilation by Fogg and Gerrard (72). Diffusion coefficients of propane and methane in these liquids were estimated using the Tyn and Calus correlation (46 48),...

---