Homologous series,thermodynamic

In a homologous series thermodynamic correlations are often discovered in kinetics, similar correlations are found for families of reactions. 

Comparison of calculated and experimental data. Since the homologous series of adducts of the type Et3Al—E(Tms)3 (E = P 28, As 29, Sb 15, Bi 14) has been structurally characterized by single crystal X-ray diffraction, their structures and thermodynamic stabilities were calculated to allow a comparison between experimental and theoretical data (Table 7). 

The major breakthrough in the development of such RsE species was achieved several years ago by Sekiguchi et al., who reported the isolation and full identification of a homologous series of (t-Bu2MeSi)3E (E = Si, Ge, Sn) radicals without Jt-bond conjugation. " All of these radicals, kinetically and thermodynamically stabilized by the bulky electropositive silyl substituents, were prepared by the same very simple and straightforward method, which clearly danonstrated the generality of this synthetic approach. 

Table IX shows the thermodynamic parameters of micellization, calculated from the cmcs and their temperature dependence, for two homologues of each of these types of nonionics. It can be seen that AHm and ASm progressively decrease in the order usual-type > S > L-A > G type for both homologous series. This suggests that the high polarity of the amido linkage causes either less dehydration or exothermic association of the hydrophilic part on micelle formation.

Abraham. M.H. Thermodynamics of solution of homologous series of solutes in water, /. Chem. Soc., Faraday Trans. 1, 80(1) 153-181. 1984. 

Table 5 Thermodynamic Properties for a Homologous Series of N-Substituted NOSI3 in Toulene...

Scamehorn et. al. (20) also presented a simple, semi—empirical method based on ideal solution theory and the concept of reduced adsorption isotherms to predict the mixed adsorption isotherm and admicellar composition from the pure component isotherms. In this work, we present a more general theory, based only on ideal solution theory, and present detailed mixed system data for a binary mixed surfactant system (two members of a homologous series) and use it to test this model. The thermodynamics of admicelle formation is also compared to that of micelle formation for this same system. 

Based on the fluorite-type module theory the thermodynamic properties, hysteresis, and reactions between the homologous series can be elucidated and the structures of homologous series experimentally discovered may be modeled. Using these principles a wide range of non-stoichiometric ternary lanthanide higher oxides from RO2 to R2O3 were founded. 

Of the 15 experimentally known phases of the higher oxides only five of them have been determined by X-ray and neutron diffraction using the Rietveld refinements method. To understand the thermodynamic behavior and phase reactions it is helpful to have a model of the undetermined structures. Using the experimental electron diffraction data it is possible to determine the symmetry of the unit cell and develops a transformation matrix between the fluorite and ten of the intermediate phases as shown in Table 2. The module theory provides a method for modeling the unknown structures of the homologous series of the lanthanide... 

The lanthanide higher oxides have not only peculiar thermodynamic properties, but also unique physical and chemical properties. The physical and chemical properties are presented as a macroscopic parameter, such as the electrical conductivity, the coefficient of expansion, and the conversion rate of a catalysis process. Due to the lack of knowledge of the wide range of non-stoichiometry of the oxygen-deficient fluorite-related homologous series of the lanthanide higher oxides, the macroscopically measured data of the physical and chemical properties are scattered, and therefore, based on the structural principle of the module ideas a deep understanding the relationship between the properties and structures is needed. 

The thermodynamic properties for a wide range of solutes (Table 4 Franks and Reid, 1973) show a trend which again points to the importance of the apolar hydration. For example, within a given homologous series, the partial molar heat capacities show a positive... 

The most important correlations are those based on regularities between retention data and the number of carbon atoms in the solute molecule, existing within homologous series of compounds [17]. All of these correlations have a certain thermodynamic basis,... 

The adsorption of binary mixtures of anionic surfactants of a homologous series (sodium octyl sulfate and sodium dodecyl sulfate) on alpha aluminum oxide was measured. A thermodynamic model was developed to describe ideal mixed admicelle (adsorbed surfactant bilayer) formation, for concentrations between the critical admicelle concentration and the critical micelle concentration. Specific... 

Let us return now to the oxidation of butane. We will illustrate the generation of feasible pathways using K. In this example, K was restricted to thermodynamically viable free-radical pathways products were restricted to their homologous series. The generation call was... 

Another procedure based only in part on the additivity properties of the values for AH and AS° is based on correlation equations for a series of homolog compounds or of compounds containing a repetitive unit (such as polymers). Since the compounds in a homolog series differ by the same fragment, it can be expected that the values in a series is linear The data used for generating the correlation equation can be either experimental or calculated values of a thermodynamic parameter. As an example, a set of experimental and calculated values for the heats of formation AHf for the series of saturated normal hydrocarbons CnH2n.,2 are plotted as a function of carbon number in Figure 2,2.4. 

At constant temperature, pressure, and composition also r is constant, i.e. at thermodynamic equilibrium the ratio of the molar fractions of the successive members of the homologous series of silicate anions is constant. 

To analyze such thermodynamic relations of different molecules, we will take the model system to be a homologous series of normal alkanes and alkenes, as very reliable and accurate data are available in the literature. Linear hydrocarbon chains, n-alkanes, are among the most common blocks of organic matter. They form part of the organic and biological molecules of lipids, surfactants, and liquid crystals and determine their properties to a large extent. As major constituents of oils, fuels, polymers, and lubricants, they also have immense industrial importance. Accordingly, their bulk properties have been extensively studied. 

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