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Urszula Domanska - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic study of molecular interactions in eutectic mixtures containing camphene
Journal of Physical Chemistry B, 2016Co-Authors: Marcin Okuniewski, Kamil Paduszynski, Urszula DomanskaAbstract:Terpenes are an abundant and diverse class of chemicals having numerous applications in different areas of chemistry. Therefore, a detailed knowledge of physical and thermodynamic properties of terpenes and their mixtures with other compounds is highly desired. This paper reports both a thermodynamic study on solid–liquid equilibrium (SLE) phase diagrams in binary systems formed by (±)-camphene (a representative terpene) and one of the following solvents: n-decane, n-dodecane, 1-decanol, 1-dodecanol, phenylmethanol, 2-phenylethanol, 2-cyclohexylethanol. The observed trends in the measured SLE data are discussed in terms of structure (alkyl chain length, aromacity) of the solvent and molecular interactions. Modeling of the considered SLE phase diagrams with three well-established thermodynamic models, namely, modified UNIFAC (Dortmund), perturbed-chain statistical associating fluid theory (PC-SAFT) and conductor-like screening model for real solvents (COSMO-RS), is presented. A comparative analysis of thei...
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solubility of ionic liquids in water and octan 1 ol and octan 1 ol water or 2 phenylethanol water partition coefficients
The Journal of Chemical Thermodynamics, 2012Co-Authors: Aneta Pobudkowska, Marek Krolikowski, Urszula Domanska, Patrycja BochenskaAbstract:Abstract The solubility of 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate, [EMIM][FAP] and 1-hexyl-3-methylpyridinium triflate, [HM 3 Py][CF 3 SO 3 ] in octan-1-ol, water, and 2-phenylethanol have been determined at ambient pressure. A dynamic method was used over a broad range of mole fractions and temperatures from 270 K to 360 K. The immiscibility in the liquid phase with an upper critical solution temperature (UCST) was observed in ([EMIM][FAP] + octan-1-ol, or water). The complete miscibility in the liquid phase was observed for the binary system ([EMIM][FAP] + 2-phenylethanol). The simple liquidus curves with complete miscibility in the liquid phase were observed for the binary systems ([HM 3 Py][CF 3 SO 3 ] + 1-octanol, or 2-phenylethanol) and with miscibility gap in water. The octan-1-ol/water, K ow and 2-phenylethanol/water, K Phw partition coefficients in ternary liquid-liquid phase equilibrium were determined for the systems {[EMIM][FAP], or [HM 3 Py][CF 3 SO 3 ], or N -octylisoquinolinium bis{(trifluoromethyl)sulfonyl}imide, [OiQuin][NTf 2 ] (1) + octan-1-ol (2) + water (3)} at temperature T = 298.15 K.
Alberto J Marchi - One of the best experts on this subject based on the ideXlab platform.
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liquid phase dehydration of 1 phenylethanol over hzsm 5 kinetic modeling
Catalysis Communications, 2009Co-Authors: Nicolas M Bertero, Carlos R. Apesteguía, Alberto J MarchiAbstract:Abstract The liquid-phase dehydration of 1-phenylethanol over HZSM-5 zeolite (Si/Al = 20), at 353–373 K and using cyclohexane as solvent, was studied. Varying initial reactant concentration, a negative order respect to 1-phenylethanol was determined. In all cases, HZSM-5 resulted highly selective to styrene. Experimental data were fitted using LHHW-like kinetic models. Both physical and statistical criteria were applied to discriminate the best heterogeneous kinetic model. The most satisfactory fitting was obtained assuming that styrene is formed from 1-phenylethanol interacting simultaneously with two active sites. This mechanism explains the negative order respect to 1-phenylethanol.
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liquid phase dehydration of 1 phenylethanol over mordenite like zeolites influence of si al ratio
Catalysis Communications, 2008Co-Authors: Nicolas M Bertero, Carlos R. Apesteguía, Alberto J MarchiAbstract:Abstract The liquid-phase dehydration of 1-phenylethanol over mordenite-like zeolites, with different Si/Al ratios, was studied at 363 K using cyclohexane as solvent. It was determined that catalyst activity and selectivity greatly depended on the Si/Al ratio. The non-dealuminated mordenite showed the lowest activity, dehydrating 1-phenylethanol mainly to α-methylbenzyl ether via an intermolecular mechanism. Instead, intramolecular dehydration of 1-phenylethanol into styrene was mainly observed over dealuminated samples. Changes in catalytic performance with Si/Al ratio was explained on the basis of: (1) acid site density; (2) relative amount of strong acid sites respect to weak ones; (3) accessibility to strong acid sites.
Gloria Villora - One of the best experts on this subject based on the ideXlab platform.
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ternary liquid liquid equilibria for mixtures of an ionic liquid n hexane an organic compound involved in the kinetic resolution of rac 1 phenyl ethanol rac 1 phenyl ethanol vinyl propionate rac 1 phenylethyl propionate or propionic acid at 298 2 k a
Fluid Phase Equilibria, 2008Co-Authors: F J Hernandezfernandez, Antonia Perez De Los Rios, Demetrio Gomez, Manuel Rubio, F Tomasalonso, Gloria VilloraAbstract:Abstract The liquid–liquid equilibrium of 16 ternary systems containing an ionic liquid + n-hexane + an organic compound involved in the racemic resolution of rac-1-phenylethanol (rac-1-phenylethanol, vinyl propionate, 1-phenylethyl propionate or propionic acid) at 298.2 K and atmospheric pressure have been measured. The ionic liquids used were (i) 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim+][PF6−]; (ii) 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim+][BF4−]; (iii) 1-ethyl-3-methylimidazolium tosilate, [emim+][TOS−] and (iv) 1-butyl-3-methyl imidazolium ethylenglykolmonomethylethersulfate, [bmim+][MDEGSO4−]. The binodal curves and the tie line compositions of the conjugate solutions were obtained by means of refractive index (ionic liquid rich phase) and by gas cromatography (hexane rich phase) to determine their potential for selectively extracting organic compounds from an ionic liquid reaction mixture. The tie lines were correlated by using the NTRL equation, which provides good correlation of the experimental data.
José Carlos . Cobos - One of the best experts on this subject based on the ideXlab platform.
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Liquid−Liquid Equilibria for 2‑Phenylethan-1-ol + Alkane Systems
American Chemical Society, 2018Co-Authors: Alonso Tristán Cristina, Juan Antonio . González, García De La Fuente, Isaías ., Luis Felipe . Sanz, José Carlos . CobosAbstract:The liquid–liquid equilibrium (LLE) curves for 2-phenylethan-1-ol (2-phenylethanol, 2PhEtOH) + octane, + decane, + dodecane, + tetradecane or + 2,2,4-trimethylpentane have been determined by a method of turbidimetry using a laser scattering technique. Experimental results reveal that the systems are characterized by an upper critical solution temperature (UCST), which increases linearly with the number of C atoms of the n-alkane. In addition, the LLE curves have a rather horizontal top and become skewed to higher mole fractions of the n-alkane, when its size increases. For a given n-alkane, UCST decreases as follows: phenol > phenylmethanol > 2-PhEtOH, indicating that dipolar interactions decrease in the same sequence. This has been ascribed to a weakening in the same order of the proximity effects between the phenyl and OH groups of the aromatic alkanols. DISQUAC interaction parameters for OH/aliphatic and OH/aromatic contacts in the investigated systems are reported. Phenol, or phenylmethanol or 2-PhEtOH, + n-alkane mixtures only differ by the first dispersive Gibbs energy interaction parameter for the (OH/aliphatic) contactJunta de Castilla y León, under Project BU034U16 F
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thermodynamics of mixtures containing aromatic alcohols 1 liquid liquid equilibria for phenylmethanol alkane systems
Journal of Chemical & Engineering Data, 2012Co-Authors: Juan Antonio . González, Cristina Alonsotristan, Isaias Garcia De La Fuente, José Carlos . CobosAbstract:The liquid–liquid equilibrium (LLE) curves for (phenylmethanol + CH3(CH2)nCH3) mixtures (n = 5, 6, 8, 10, 12) have been obtained by the critical opalescence method using a laser scattering technique. All of the systems show an upper critical solution temperature (UCST). In addition, the LLE curves have a rather horizontal top, and their symmetry depends on the alkane size. The UCST increases almost linearly with n. For systems including a given alkane and phenol or phenylmethanol, the UCST is much higher than that of the corresponding mixtures with hexan-1-ol or heptan-1-ol. This reveals that dipolar interactions are stronger in solutions with aromatic alcohols. Preliminary DISQUAC interaction parameters for OH/aliphatic contacts in the investigated systems were obtained. It is remarkable that the coordinates of the critical points of (phenol or phenylmethanol + alkane) mixtures can be described using the same quasichemical interaction parameters for the OH/aliphatic and OH/aromatic contacts.
Johann Heider - One of the best experts on this subject based on the ideXlab platform.
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asymmetric reduction of ketones and β keto esters by s 1 phenylethanol dehydrogenase from denitrifying bacterium aromatoleum aromaticum
Applied Microbiology and Biotechnology, 2015Co-Authors: Agnieszka Dudzik, Wojciech Snoch, Pawel Borowiecki, J Opalinskapiskorz, Malgorzata Witko, Johann Heider, Maciej SzaleniecAbstract:Enzyme-catalyzed enantioselective reductions of ketones and keto esters have become popular for the production of homochiral building blocks which are valuable synthons for the preparation of biologically active compounds at industrial scale. Among many kinds of biocatalysts, dehydrogenases/reductases from various microorganisms have been used to prepare optically pure enantiomers from carbonyl compounds. (S)-1-phenylethanol dehydrogenase (PEDH) was found in the denitrifying bacterium Aromatoleum aromaticum (strain EbN1) and belongs to the short-chain dehydrogenase/reductase family. It catalyzes the stereospecific oxidation of (S)-1-phenylethanol to acetophenone during anaerobic ethylbenzene mineralization, but also the reverse reaction, i.e., NADH-dependent enantioselective reduction of acetophenone to (S)-1-phenylethanol. In this work, we present the application of PEDH for asymmetric reduction of 42 prochiral ketones and 11 β-keto esters to enantiopure secondary alcohols. The high enantioselectivity of the reaction is explained by docking experiments and analysis of the interaction and binding energies of the theoretical enzyme-substrate complexes leading to the respective (S)- or (R)-alcohols. The conversions were carried out in a batch reactor using Escherichia coli cells with heterologously produced PEDH as whole-cell catalysts and isopropanol as reaction solvent and cosubstrate for NADH recovery. Ketones were converted to the respective secondary alcohols with excellent enantiomeric excesses and high productivities. Moreover, the progress of product formation was studied for nine para-substituted acetophenone derivatives and described by neural network models, which allow to predict reactor behavior and provides insight on enzyme reactivity. Finally, equilibrium constants for conversion of these substrates were derived from the progress curves of the reactions. The obtained values matched very well with theoretical predictions.
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crystal structure and enzyme kinetics of the s specific 1 phenylethanol dehydrogenase of the denitrifying bacterium strain ebn1
Biochemistry, 2006Co-Authors: Wolfgang H Hoffken, Minh Duong, Michael Breuer, Bernhard Hauer, Richard Reinhardt, Ralf Rabus, Thomas Friedrich, Johann HeiderAbstract:(S)-1-Phenylethanol dehydrogenase (PED) from the denitrifying bacterium strain EbN1 catalyzes the NAD+-dependent, stereospecific oxidation of (S)-1-phenylethanol to acetophenone and the biotechnologically interesting reverse reaction. This novel enzyme belongs to the short-chain alcohol dehydrogenase/aldehyde reductase family. The coding gene (ped) was heterologously expressed in Escherichia coli and the purified protein was crystallized. The X-ray structures of the apo-form and the NAD+-bound form were solved at a resolution of 2.1 and 2.4 A, respectively, revealing that the enzyme is a tetramer with two types of hydrophobic dimerization interfaces, similar to β-oxoacyl-[acyl carrier protein] reductase (FabG) from E. coli. NAD+-binding is associated with a conformational shift of the substrate binding loop of PED from a crystallographically unordered “open” to a more ordered “closed” form. Modeling the substrate acetophenone into the active site revealed the structural prerequisites for the strong enanti...
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s 1 phenylethanol dehydrogenase of azoarcus sp strain ebn1 an enzyme of anaerobic ethylbenzene catabolism
Archives of Microbiology, 2001Co-Authors: Olaf Kniemeyer, Johann HeiderAbstract:The initial steps in the anaerobic oxidation of the aromatic hydrocarbon ethylbenzene by denitrifying bacteria are two sequential dehydrogenation reactions of ethylbenzene to (S)-1-phenylethanol and further to acetophenone. The enzyme catalysing the second oxidation step, (S)-1-phenylethanol dehydrogenase, was analysed in the denitrifying bacterium Azoarcus sp. strain EbN1. An NAD+-dependent 1-phenylethanol dehydrogenase for each of the enantiomers of 1-phenylethanol was identified in this bacterium; the two enzymes were induced under different growth conditions. (S)-1-phenylethanol dehydrogenase from ethylbenzene-grown cells was purified and biochemically characterised. The enzyme is a typical secondary alcohol dehydrogenase and consists of two subunits of 25.5 kDa. The enantioselective enzyme catalyses the oxidation of (S)-1-phenylethanol or the reduction of acetophenone and is inhibited by high concentrations of (R)-1-phenylethanol. The enzyme exhibits low apparent Km values for (S)-1-phenylethanol and acetophenone and is rather substrate-specific, using only a few chemically similar secondary alcohols, such as 1-phenylpropanol and isopropanol.
