Alkanes thermodynamic properties

Verlet, L. Computer experiments on classical fluids. I. Thermodynamical properties of Lennard-Jones molecules. Phys. Rev. 165 (1967) 98-103. Ryckaert, J.-P., Ciccotti,G., Berendsen, H.J.C. Numerical integration of the cartesian equations of motion of a system with constraints Molecular dynamics of n-alkanes. Comput. Phys. 23 (1977) 327-341. 

It was shown in the previous section that different relatively stable conformations of a given molecule can result from internal rotation of a particular functional group. The possibility of the existence of various conformers is of extreme importance in many applications. It should be noted, for example, that the biological activity of an organic molecule often depends on its confonfia-tion - in particular the relative orientation of a specific functional grtmp. As another example, the thermodynamic properties of, say, an alkane are directly related to the conformation of its carbon skeleton. In this context the industrial importance of /sooctane is well-known. 

Sugiyama, T., Takeuchi, T., Suzuki, Y. (1975) Thermodynamic properties of solute molecules at infinite dilution determined by gas-liquid chromatography. I. Intermolecular energies of w-alkane solutes in C28 - C36 w-alkane solvents. J. Chromatogr. 105,265-272. 

Thermodynamic properties of alkane chains 13 Thermodynamic properties of ring compounds 15 Enthalpy and entropy effects on ring closure 21... 

In marked contrast to the n-alkanes, the cycloalkanes exhibit thermodynamic properties where such regularities are no longer present. Heats of formation (AH ) for a substantial number of cycloalkanes are available from heats of combustion. With the exception of cyclohexane, AH°f is always more positive than the quantity — 4.926n. The difference between the two quantities leads to a quantitative assessment of the important notion of ring strain. The AH -values and strain energy data listed in Table 1 were taken from Skinner and Pilcher (1963). Other references give different but usually comparable... 

Traube s rule accommodates the balance between hydrophobicity and hydro-philicity. It has been extended somewhat and formalized with the development of quantitative methods to estimate the surface area of molecules based on their structures [19, 237]. The molecular surface area approach suggests that the number of water molecules that can be packed around the solute molecule plays an important role in the theoretical calculation of the thermodynamic properties of the solution. Hence, the molecular surface area of the solute is an important parameter in the theory. In compounds other than simple normal alkanes, the functional groups will tend to be more or less polar and thus relatively compatible with the polar water matrix [227,240]. Hence, the total surface area of the molecule can be subdivided into functional group surface area and hydro carbonaceous surface area . These quantities maybe determined for simple compounds as an additive function of constituent groups with subtractions made for the areas where intramolecular contact is made and thus no external surface is presented. 

Martinez, R., Gonzalez, J.A., de la Fuenta, LG., and Cobos, J.C. Thermodynamic properties of n-alkoxyethanols + organic solvent mixtures. XIV. Liquid-liquid equilibria of systems containing 2-(2-ethoxyethoxy)ethanol and selected alkanes. J. Chem. Eng. Data, 45(6) 1036-1039, 2000. 

Heintz, A., Kulikov, D.V., and Verevkin, S.R, Thermodynamic properties of mixtures containing ionic liquids. 1. Activity coefficients at infinite dilution of alkanes, alkenes, and alkylbenzenes in 4-methyl-M-butylpyridinium tetrafluo-roborate using gas-liquid chromatography, /. Chem. Eng. Data, 46,1526,2001. 

Heats of formation assume resonance stabilizations 10.8 kcal mole-1 in ( CHaCN) 12.6 kcal mole-1 in (CH3CHCN) and in [(CH3)2CCN]. " Na = doubly bonded nitrogen in azo compounds. h This correction assumes that the barrier to rotation in the radical R is two-thirds the barrier in the corresponding alkane RH. See O Neal and Benson for further discussion of this point. AH° and to +2 cal mole-1 °K 1 for 5°. The following example shows how the table is used to calculate thermodynamic properties for the 2-butyl radical (12).41 H3C—ch—ch2—ch3 12 ... 

Alkanes that we will use as examples in this section may have a small dipole moment. We may instead have appropriately titled this section as Almost (Nonpolar + Nonpolar) Mixtures . The mixtures we describe first are at ambient pressure p ss 0.1 MPa). Later we will describe the effect of pressure on the excess thermodynamic properties. 

Figure 13.6 shows a schematic for IGC operation. Inverse, in this instance, refers to the observation that the powder is the unknown material, and the vapor that is injected into the column is known, which is inverse to the conditions that exist in traditional gas chromatography. After the initial injection of the known gas probe, the retention time and volume of the probe are measured as it passes through the packed powder bed. The gas probes range from a series of alkanes, which are nonpolar in nature, to polar probes such as chloroform and water. Using these different probes, the acid-base nature of the compound, specific surface energies of adsorption, and other thermodynamic properties are calculated. The governing equations for these calculations are based upon fundamental thermodynamic principles, and reveal a great deal of information about the surface of powder with a relatively simple experimental setup (Fig. 13.6). This technique has been applied to a number of different applications. IGC has been used to detect the following scenarios ...

Hosoya, H., Gotoh, M., and Ikeda, S., Topological index and thermodynamic properties. 5. How can we explain the topological dependency of thermodynamic properties of alkanes with the topology of graphs , J. Chem. Inf. Comput. Sci., 39, 192-196, 1999. 

Group contributions for the interaction energy, ekk T, the surface area, Qk, and the reference volume, Rk, for the High-Danner model have been calculated for the alkanes, alkenes, cycloalkanes, aromatics, esters, alcohols, ethers, water, ketones, aromatic ketones, amines, siloxanes, and monochloroalkanes. If solvents and polymers of interest contain these building blocks, the thermodynamic properties can be calculated. More detailed information concerning the High-Danner equation of state is given in Procedure 3E. 

Sugamiya, K. Kuwahara, N. Kaneko, M., "Thermodynamic Properties of Moderately Concentrated Solutions of Poly(dimethylsiloxane) in n-Alkanes," Macromolecules, 7, 66 (1974). 

Acree, W.E., McCargar, J.W., Zvaigzne, A.I., Teng, I.L., 1991. Mathematical representation of thermodynamic properties. Carbazole solubilities in binary alkane + dibutyl ether and alkane + tetrahydropyran solvent mixtures. Phys. Chem. Liq. 23, 27-35. 

Acree, W. E. McCargar, J. W. Zvaigzne, A. 1. Teng, 1. L. Mathematical representation of thermodynamic properties -carbazole solubilities in binary alkane -E dibutyl ether and alkane... 

Gao, Y. and Hosoya, H. (1988). Topological Index and Thermodynamics Properties. IV. Size Dependency of the Structure-Activity Correlation of Alkanes. Bull.Chem.Soc.Jap., 61, 3093-3102. 

Davydov et al. [46] used IGC to determine several adsorption thermodynamic properties (equilibrium constants and adsorption heats) for the adsorption of organic compounds on C q crystals, and compared them with those obtained for graphitized carbon black. The adsorption potential of the surface of fiillerene crystals was much lower than that of a carbon black surface. The dispersive interaction of organic molecules with C q is much weaker than with carbon black. The adsorption equilibrium constant for alkanes and aromatic compounds is therefore lower in the case of fullerenes. Aliphatic and aromatic alcohols as well as electron-donor compounds such as ketones, nitriles and amines were adsorbed more efficiently on the surface of fiillerene crystals. This was taken as proof that fiillerene molecules have electron-donor and electron-acceptor properties, which is in agreement with the results of Abraham et al. [44]... 

M. Dirand, M. Bouroukba, V. Chevallier, D. Petitjean, E. Behar, V, Ruffier-Meray (2002). J. Chem. Eng. Data, 47, 115-143. Normal alkanes, multialkane synthetic model mixtures, and real petroleum waxes Crystallographic structures, thermodynamic properties, and crystallization. 

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