Compilation and critical analysis of thermodynamic data for ternary alloy systems

The thermodynamic approach in resolving industrial problems concerned with high temperature has led, in the two last decades, to a notable development of both theoretical and experimental studies on multicomponent system. Phase diagram determinations of metallic systems are still carried out very extensively because of their importance in the field of material science, mainly in steelmaking, non-ferrous metallurgy, crystal growth, electroslag- refining, nuclear materials, etc..

Thermodynamics of Mixtures Containing Amines. XV. Liquid–Liquid Equilibria for Benzylamine + CH3(CH2)nCH3 (n = 8, 9, 10, 12, 14)

Coexistence curves for the liquid−liquid equilibria (LLE) of 1-phenylmethanamine (benzylamine) + CH3(CH2)nCH3 (n = 8, 9, 10, 12, 14) have been determined using the critical opalescence method by means of a laser scattering technique. All of the LLE curves show an upper critical solution temperature (UCST), which increases with increasing n. For systems including a given n-alkane, the UCST decreases in the sequence aniline > 2-methylaniline (o-toluidine) > benzylamine > N-methylaniline > pyridine. This means that amine−amine interactions become weaker in the same order. Most of the DISQUAC interaction parameters for the aliphatic/amine (a,n) and aromatic/ amine (b,n) contacts previously determined for solutions with aniline, o-toluidine, or N-methylaniline have been used for the representation of the LLE data. Only the first dispersive interaction parameter of the (a,n) contact has been modified. The coordinates of the critical points are correctly represented by the model

Computer-Aided Solvent Screening for Biocatalysis

A computer-aidedsolventscreening methodology is described and tested for biocatalytic systems composed of enzyme, essential water and substrates/products dissolved in a solvent medium, without cells. The methodology is computationally simple, using group contribution methods for calculating constrained properties related to chemical reaction equilibrium, substrate and product solubility, water solubility, boiling points, toxicity and others. Two examples are provided, covering the screening of solvents for lipase-catalyzed transesterification of octanol and inulin with vinyl laurate. Esterification of acrylic acid with octanol is also addressed. Solvents are screened and candidates identified, confirming existing experimental results. Although the examples involve lipases, the method is quite general, so there seems to be no preclusion against application to other biocatalyst

Orientational Effects and Random Mixing in 1-Alkanol + Alkanone Mixtures

1-Alkanol + alkanone systems have been investigated through the data analysis of molar excess functions, enthalpies, isobaric heat capacities, volumes and entropies, and using the Flory model and the formalism of the concentrationconcentration structure factor (SCC(0)). The enthalpy of the hydroxyl-carbonyl interactions has been evaluated. These interactions are stronger in mixtures with shorter alcohols (methanol-1-butanol) and 2-propanone or 2-butanone. However, effects related to the self-association of alcohols and to solvation between unlike molecules are of minor importance when compared with those which arise from dipolar interactions. Physical interactions are more relevant in mixtures with longer 1-alkanols. The studied systems are characterized by large structural effects. The variation of the molar excess enthalpy with the alcohol size along systems with a given ketone or with the alkanone size in solutions with a given alcohol are discussed in terms of the different contributions to this excess function. Mixtures with methanol show rather large orientational effects. The random mixing hypothesis is attained to a large extent for mixtures with 1-alkanols ≠ methanol and 2-alkanones. Steric effects and cyclization lead to stronger orientational effects in mixtures with 3-pentanone, 4-heptanone, or cyclohexanone. The increase of temperature weakens orientational effects. Results from SCC(0) calculations show that homocoordination is predominant and support conclusions obtained from the Flory model.Ministerio de Ciencia e Innovación, under Project FIS2010-1695

Orientational Effects and Random Mixing in 1‑Alkanol + Nitrile Mixtures

1-Alkanol + alkanenitrile or + benzonitrile systems have been investigated by means of the molar excess functionsenthalpies (Hm E ), isobaric heat capacities (Cp,m E ), volumes (Vm E ), and entropiesand using the Flory model and the concentration−concentration structure factor (SCC(0)) formalism. From the analysis of the experimental data available in the literature, it is concluded that interactions are mainly of dipolar type. In addition, large Hm E values contrast with rather low Vm E values, indicating the existence of strong structural effects. Hm E measurements have been used to evaluate the enthalpy of the hydroxyl−nitrile interactions (ΔHOH−CN). They are stronger in methanol systems and become weaker when the alcohol size increases. In solutions with a given short chain 1-alkanol (up to 1-butanol), the replacement of ethanenitrile by butanenitrile weakens the mentioned interactions. Application of the Flory model shows that orientational effects exist in methanol or 1- nonanol, or 1-decanol + ethanenitrile mixtures. In the former solution, this is due to the existence of interactions between unlike molecules. For mixtures including 1-nonanol or 1-decanol, the systems at 298.15 K are close to their UCST (upper critical solution temperature), and interactions between like molecules are dominant. Orientational effects also are encountered in methanol or ethanol + butanenitrile mixtures because self-association of the alcohol plays a more important role. Aromaticity effect seems to enhance orientational effects. For the remainder of the systems under consideration, the random mixing hypothesis is attained to a rather large extent. Results from the application of the SCC(0) formalism show that homocoordination is the dominant trend in the investigated solutions, and are consistent with those obtained from the Flory model

Enthalpy of mixing of ethers with hydrocarbons at 25 °C and its analysis in terms of molecular surface interactions

Les ailleurs rapportent les enthalpies de mélange, à 25 °C sous pression atmosphérique, des systèmes binaires suivants : l'éthyl , le n-propyl- et le n-butylbenzène avec le n-heptane; l'éther méthyl-n-butylique avec le n-heptane; le 2,5-dioxa- hexane avec le n-heptane et le n-nonane; le 2,5,8-trioxanonane avec le n-heptane et le n-décane; le 3,6,9-trioxaundécane avec le n-heptane et le n-nonane; les éthers méthyl-n-butylique, méthyl-n-amylique, éthyl-n-butylique, méthyl-n-amylique, éthyl-n-butylique et di-n-propylique, le 2,5-dioxaliexane, le 2,5,8-trioxanonane et le 3,6,9-trioxaundécane avec le benzène; le méthoxybenzène, l'éther méthylbenzylique et le 1-phényl- 2-méthoxyéthane avec le n-heptane, l'éthylbenzène et l'éther méthyl-n-butylique.Les données expérimentales sont interprétées en termes d'interactions entre les surfaces moléculaires en utilisant des équations dérivées de la théorie du réseau de GUGGENHEIM pour les mélanges de molécules hétérogènes, dans l'approxi- mation zéro. Les enlhalpies de mélange expérimentales de presque tous les systèmes étudiés ont pu être reproduites à l'aide d'un paramètre caractérisant la surface de contact du benzène et trois paramètres représentant les enthalpies d'inter- échanges des paires de surfaces de contact : aliphatique/aro- matique, aliphatique/oxygène éthérique et oxygène éthé- rique/aromatique. Tous ces paramètres ont été déterminés d'une façon systématique. Les déviations prévues, dues aux effets stériques et inductifs, ont été effectivement observées dans le cas des systèmes contenant le méthoxybenzène. En plus, les auteurs donnent une discussion qualitative des enthalpies de mélange mesurées, en termes d'interactions π — π et n — π