Search results for "Azeotrope"
showing 10 items of 64 documents
Enhanced crystal stability in a binary mixture of charged colloidal spheres.
2009
We report on the phase behavior of a binary charged sphere mixture of size ratio $\ensuremath{\Gamma}=0.68$ and charge ratio $\ensuremath{\Lambda}\ensuremath{\approx}1$ as a function of composition $p$ and number density $n$. For $p=0.1--0.3$ we observe freezing at densities well below the freezing densities of the pure components. At all compositions our data indicate the formation of substitutional alloy crystals of body centered cubic structure. No indications for compound formation were observed. Rather, our findings point at the first observation of an upper azeotrope. Measurements of the crystallization kinetics reveal a combined density and composition dependence of growth velocities…
Phase equilibria and multiple azeotropy in the associating system methanol + diethylamine
1997
Vapor−liquid equilibrium has been measured for the binary system of methanol (1) + diethylamine (2) at 101.3 and 300 kPa. Both equilibrium isobars show strong deviations from ideal behavior and a single maximum boiling point azeotrope of practically constant composition x1 ≈ 0.76, corresponding to a temperature of 339.8 K at 101.3 kPa and 370.0 K at 300 kPa. The trend of the high-pressure isobar data is consistent with the formation of a second minimum boiling azeotrope, confirming the multiple azeotropic behavior found by others at a higher temperature (398.58 K). Furthermore, the excess Gibbs energy is negative and inflects markedly with composition with increased pressure. The equilibriu…
Proposal of Isobutyl Alcohol as Entrainer To Separate Mixtures Formed by Ethanol and Water and 1-Propanol and Water
2017
Isobutyl alcohol (IBA) has been proposed as a solvent to carry out the dehydration of ethanol and 1-propanol by means of a nonconventional distillation process. In this way, isobaric vapor–liquid equilibrium (VLE) and vapor–liquid–liquid equilibrium (VLLE) data at atmospheric pressure have been obtained for the ternary systems ethanol (1a) + water (2) + IBA (3) and 1-propanol (1b) + water (2) + IBA (3). Then, these data have been correlated to obtain a set of parameters capable of estimating VLE and VLLE. According to the results achieved, distillation sequences to separate water and ethanol or 1-propanol have been proposed. Finally, a study about the minimum amount of entrainer required to…
Isobaric Vapor−Liquid Equilibria for Ethyl Acetate + Ethanol + 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate at 100 kPa
2007
Isobaric vapor−liquid equilibria for the binary systems ethyl acetate + ethanol, ethyl acetate + 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][triflate]), and ethanol + [emim][triflate] as well as the vapor−liquid equilibria for the ethyl acetate + ethanol + [emim][triflate] ternary system have been obtained at 100 kPa using a recirculating still. NRTL fitting parameters for the ethyl acetate + ethanol and ethanol + [emim][triflate] systems were calculated. The measured ternary data were correlated using the Mock electrolyte NRTL model, which reproduces reasonably well the experimental values. The results suggest that the addition of [emim][triflate] to the ethyl acetate + e…
Isobaric Vapor–Liquid Equilibria of 1-Propanol + Water + Trifluoromethanesulfonate-Based Ionic Liquid Ternary Systems at 100 kPa
2011
Isobaric vapor–liquid equilibria (VLE) for the 1-propanol + 1-butyl-3-ethylimidazolium trifluoromethanesulfonate ([beim][triflate]), water + [beim][triflate], 1-propanol + 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([bmpyr][triflate]), and water + [bmpyr][triflate] binary systems, as well as the VLE for the 1-propanol + water + [beim][triflate] and 1-propanol + water + [bmpyr][triflate] ternary systems have been obtained at 100 kPa using a recirculating still. The salting-out effect on the 1-propanol produced by the [bmpyr][triflate] was stronger than that produced by the [beim][triflate], although for the IL concentrations used in this study the effect was not enough to break …
Sustainable Approach to Waste-Minimized Sonogashira Cross-Coupling Reaction Based on Recoverable/Reusable Heterogeneous Catalytic/Base System and Ace…
2016
In this contribution, we present a chemically efficient and sustainable protocol for the palladium-catalyzed copper-free Sonogashira cross-coupling reaction, based on the use of a heterogeneous catalytic system. This consists in the combination of a palladium catalyst on highly cross-linked thiazolidine network on silica and a polystyrene-supported base. The solid catalyst/base system acts as a palladium scavenger avoiding leaching of the metal and consequent product contamination. The reaction can be conducted in safe and easily recoverable acetonitrile/water azeotrope as reaction medium. This proved to be an efficient greener alternative to the classic toxic aprotic media commonly used in…
Solvent Effects on Vapor–Liquid Equilibria of the Binary System 1-Hexene + n-Hexane
2012
In order to study the separation of 1-hexene and n-hexane, two solvents, 2-pentanol and ethyl-butyrate, are tested as possible entrainers for an extractive distillation. In this way, isobaric vapor–liquid equilibrium (VLE) data at 100 kPa have been measured for the two ternary systems formed by the initial mixture and one of the mentioned solvents: 1-hexene + n-hexane + ethyl butyrate and 1-hexene + n-hexane + 2-pentanol. VLE data for the four constituent binary systems have also been measured. These systems are 1-hexene + ethyl butyrate, n-hexane + ethyl butyrate, 1-hexene + 2-pentanol, and finally n-hexane + 2-pentanol. All binary systems show moderate positive deviations from the ideal b…
Über die Verwendung von homogenen azeotropen Gemischen in der Dünschichtchromatographie, 1. Mitt.
1968
Homogene azeotrope Gemische wurden auf ihre Brauchbarkeit fur die Dunnschichtchromatographie untersucht. Mehrere Gemische zeigten sich zur Trennung verschiedener Substanzklassen, z. B. Alkaloiden oder Sulfonamiden geeignet. Die DC mit diesen Gemischen fuhrt zu besonders konstanten Rf-Werten und zeichnet sich durch Wirtschaftlichkeit aus. The usefulness of homogeneous azeotropic mixtures in thin layer chromatography has been studied. Several mixtures are qualified for the separation of different classes of substances, for example alkaloids and sulfonamides. TLC with azeotropic solvents leads to especially constant Rf-values and is remarkably economical.
Substitution of carcinogenic solvent dichloromethane for the extraction of volatile compounds in a fat-free model food system
2016
International audience; Dichloromethane is known as a very efficient solvent, but, as other halogenated solvents, is recognized as a hazardous product (CMR substance). The objective of the present work is to propose substitution solvent for the extraction of volatile compounds. The most important physico-chemical parameters in the choice of an appropriate extraction solvent of volatile compounds are reviewed. Various solvents are selected on this basis and on their hazard characteristics. The selected solvents, safer than dichloromethane, are compared using the extraction efficiency of volatile compounds from a model food product able to interact with volatile compounds. Volatile compounds …
Vapor-liquid equilibria for the binary systems of methylcyclohexane with 1-propanol, 2-propanol, 1-butanol, and 2-butanol at 101.3 kPa
1997
Isobaric vapor−liquid equilibrium measurements at 101.3 kPa are reported for the binary systems methylcyclohexane + 1-propanol, + 2-propanol, + 1-butanol, and + 2-butanol. The systems show a strong positive deviation from ideality and present a minimum temperature azeotrope. The activity coefficients were found to be thermodynamically consistent by the methods of Van Ness−Byer−Gibbs and Wisniak. The date were correlated with five liquid-phase activity coefficient models (Margules, Van Laar, Wilson, NRTL, and UNIQUAC). According to the average deviations in temperature and in vapor composition the best model for the systems is NRTL.