Phase Equilibria and Volumetric Properties in Binary Mixtures Containing Branched Chain Ethers (Methyl 1,1-Dimethylethyl Ether or Ethyl 1,1-Dimethylethyl Ether or Methyl 1,1-Dimethylpropyl Ether or Ethyl 1,1-Dimethylpropyl Ether)

Abstract

The solid−liquid equilibrium (SLE) has been measured above 280 K for eight mixtures of n-alkanes (octadecane, eicosane, docosane, tetracosane, pentacosane, hexacosane, heptacosane, octacosane) with methyl 1,1-dimethylethyl ether (MTBE). Experimental results of solubility are compared with values calculated by means of the Wilson, UNIQUAC, and NRTL equations utilizing parameters taken from the SLE. The existence of a solid−solid first-order phase transition in hydrocarbons has been taken into consideration in the solubility calculations. The solubility of hydrocarbons in branched chain ethers is lower than that in n-alkanes but higher than that in cycloalkanes, branched alkanes, 1-alcohols, and tert-alcohols. The best correlation of the solubility data has been obtained by the NRTL equation, where the average root-mean-square deviation of the solubility temperatures is 0.46 K. The liquid−liquid equilibrium (LLE) has been measured between 300 and 360 K for binary mixtures of water with ethyl 1,1-dimethylethyl ether, methyl 1,1-dimethylpropyl ether, and ethyl 1,1-dimethylpropyl ether. The solubility of water in branched chain ether increases with increasing temperature, whereas the solubility of ether in water is decreasing up to 330 K and at the higher temperatures is slightly increasing. The excess molar volumes have been measured at the temperatures 298.15 K and 308.15 K for binary mixtures of hexane, octane, decane, dodecane, tetradecane, hexadecane, cyclohexane, and 1-heptyne with ethyl 1,1-dimethylpropyl ether. The excess molar volumes of all mixtures except for 1-heptyne are positive over the whole composition range. The experimental results have been correlated with the Redlich−Kister polynomial and compared with the results predicted from Prigogine−Flory−Patterson theory. The interchange parameter X 12, which minimized experimental data, was adjusted and then used to predict the heat of mixing.

Excess molar volumes of (hydrocarbon + ethyl 1,1-dimethylpropyl ether) atT= (298.15 and 308.15) K

“…V E m increases with increasing n-alkane length from hexane to octane {the V E m (max) values for heptane, octane and decane are very similar} and decreases with increasing n-alkane size. This has also been reported earlier (8) for (n-alkane + dipropyl ether) and for (n-alkane + MTAE, (7) or ETBE (4) ). The molar excess enthalpies increase with increasing n-alkane carbon chain as shown by us earlier.…”

“…(4) The ETAE (ethyl 1,1-dimethyl propyl ether, 919-94-8), was synthesized at the Division of Organic Chemistry, Faculty of Chemistry, Warsaw University of Technology (Poland), and purified by distillation at atmospheric pressure to a mass fraction purity better than 0.999. All liquids were stored over freshly activated molecular sieves 4A (0.4 nm, 3.2 mm pellets, Union Carbide).…”

“…(1)(2)(3)(4) Prigogine-Flory-Patterson (PFP) theory has been applied to the mixtures tested in this work, as well, using the same procedure as before. (12) The interchange parameter H E m(calc) .…”

“…(12) The interchange parameter H E m(calc) . The pure component parameters, cubic expansion coefficient, α, and isothermal compressibility, κ T , needed for calculations were partly presented previously (4) and are shown in table 5. The results of the computations are summarized in tables 6 and 7.…”

“…In recent publications, (1)(2)(3)(4) we presented excess thermodynamic properties for mixtures (hydrocarbon + branched chain ether). As an extension of these studies, we report here excess molar volumes, V E m at T = (298.15 and 308.15) K for {hexane, or cyclohexane, or benzene, or heptane, or 1-heptene, or 1-heptyne, or octane, or 2,2,4-trimethylpentane, or decane, or dodecane, or tetradecane, or hexadecane + ethyl 1,1-dimethylpropyl ether (ETAE)}.…”