Measurement and Modeling of Phase Equilibria in Systems of Acetonitrile,n-Alkanes, and β-Myrcene

Abstract

This work presents a modeling approach using the Perturbed Chain-Statistical Associating Fluid Theory (PC-SAFT) for new liquid−liquid equilibria (LLE) data of ternary systems containing β-myrcene, acetonitrile, and n-alkanes, as well as binary mixtures thereof. The modeling approach is based on parameter estimations from binary systems and allows a general prediction of acetonitrile/n-alkane systems' LLE and their ternary mixtures' LLE with β-myrcene. The binary mixtures' vapor− liquid equilibria (VLE) of β-myrcene with acetonitrile and n-alkanes were measured at 100 mbar. The ternary systems' LLE were measured at ambient pressure and 298.15 K. Experimentally investigated alkanes are n-hexane, n-heptane, and n-octane. The approach was validated by successfully predicting the ternary system containing n-dodecane. ■ INTRODUCTIONDue to the natural limitation of fossil feedstock, terpenes (such as, e.g., myrcene) have gained significant interest in the chemical industry as renewable resources. 1 Terpenes are the main components of several resins (e.g., conifers). As conifers are perennial, modest plants, farming and exploiting is possible over several years. Because of a lack of a competition to food production, terpenes are a superior starting material compared to sugar or fatty acids. Among the terpenes, β-myrcene (myrcene, Figure 1)due to its unsaturated isoprene unitis an attractive starting substance for several reaction pathways. 2 This work focuses on homogeneously catalyzed hydroamination which is fast and selective. An atom-economic conversion of myrcene provides a sustainable way to alkyl amines on the basis of renewable feedstock. As catalysts are cost intensive, a recycling and reuse of the catalyst is preferable for an economic process design.A possible strategy to achieve catalyst recycling in homogeneous catalysis is the use of thermomorphic multicomponent solvent systems (TMS), 2b which show a temperature-dependent miscibility gap. At reaction temperature, the mixture is homogeneous. This ensures a fast bulk reaction. By cooling down to separation temperature, two liquid phases are formed. Ideally, one phase carries the catalyst, whereas the product enriches in the other one. Thereby, catalyst recycling and product removal can be achieved in one step by extraction. One promising TMS for the hydroamination of myrcene is a mixture of acetonitrile with an n-alkane, whereas the catalyst (palladium with 1,4-bis(diphenylphosphino)butane as ligand) enriches in the acetonitrile-rich phase and the alkyl amine enriches in the alkane-rich phase. Until now the homogeneouscatalyzed hydroamination has been carried out with n-heptane as one TMS component. 2b It was however shown that the catalyst leaching corresponds to the concentration of the polar compound, here acetonitrile, in the apolar alkane-rich phase. 3 As the miscibility gap of TMS composed of acetonitrile and nalkanes broadens with increasing chain length of the applied alkane, a thermodynamic modeling of the phase behavior as a function of alkane chai...

Phase Equilibria in Systems of Morpholine, Acetonitrile, and n-Alkanes

“…The GC system Agilent Technology 7890A instrument was equipped with an HP 5 column (5% phenyl methyl siloxan; 30 m, 0.32 mm, 0.25 μm) and a flame ionization detector as in our previous work. 8 Vapor−Liquid Equilibrium (VLE) Measurements. VLE measurements of binary systems were performed using a glass apparatus (Normag, Ilbisheim, Germany) equipped with electrical heating, an oil-filled double-jacketed equilibrium chamber, and a water-cooled condenser for the vapor phase.…”

“…All substances except morpholine were already modeled with PC-SAFT. 8 Thus, pure-component parameters had to be estimated only for morpholine. This was done by fitting the three PC-SAFT parameters, σ i , m i , and u i /k B , as well as the permanent dipole moment of morpholine to vapor pressure 19,21−27 and liquid density 20−24 data.…”

“…The polarizability of morpholine was calculated from the refractive index 25 as described elsewhere. 8 All morpholine parameters are listed in Table 2. Using these parameters, liquid density 20−24 and vapor pressure 23,26−32 data of pure morpholine can be calculated with an average relative deviation (ARD) of 1.58 % and 0.99 %, respectively.…”

“…The latter was already successfully applied to model the LLE of the TMS ndecane/dimethylformamide used for the hydroformylation of 1-dodecene 9 and the TMS composed of acetonitrile and nalkanes with the hydroamination reactant myrcene. 8 In this work, the influence of the second hydroamination reactant, morpholine, on the LLE in the above-mentioned TMS is investigated by applying the same modeling strategy for acetonitrile/n-alkane systems as developed earlier. 8 Modeling results are compared to experimental data for systems containing n-hexane, n-heptane, and n-octane measured within this work as well as to literature data for n-decane and ndodecane systems.…”

“…8 In this work, the influence of the second hydroamination reactant, morpholine, on the LLE in the above-mentioned TMS is investigated by applying the same modeling strategy for acetonitrile/n-alkane systems as developed earlier. 8 Modeling results are compared to experimental data for systems containing n-hexane, n-heptane, and n-octane measured within this work as well as to literature data for n-decane and ndodecane systems. 10 …”