Distribution of ethanol-water mixtures to normal alkanes from C6 to C16

Roddy, J.W.; Coleman, C.F.

doi:10.1021/i100003a012

Cited by 19 publications

(14 citation statements)

References 5 publications

(6 reference statements)

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“…The increase of liquid/liquid partition coefficients of oct-1-en-3-ol, when the concentration was increased, is probably due to the auto-associations of alcohol molecules, and this hypothesis has been confirmed by infrared spectroscopy. Auto-association of alcohols has been suggested in undecane (6) and cyclohexane (7). The negative shift observed when oct-1-en-3-ol concentration was increased is typical of an intermolecular binding between oct-1-en-3-ol molecules by hydrogen bonds.…”

Section: Resultsmentioning

confidence: 95%

Interactions between volatiles and lipids in complex systems

Thanh

Goubet

Quéré

et al. 1998

J Americ Oil Chem Soc

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Partition equilibria of three aroma compounds in three different biphasic systems were studied by a liquid/liquid partition technique to investigate interactions that occur between volatiles and lipids in biphasic solutions. The lipids used were linoleic acid and ricinoleic acid and tetradecane as a model. The three aroma compounds were ethyl acetate, 2,5-dimethylpyrazine, and oct-1-en-3-ol. The results showed that the intermolecular forces involved were weak. Infrared spectroscopy was then performed on binary systems (tetradecane and linoleic acid or aroma compound) and on ternary systems (tetradecane, linoleic acid, and aroma compound) to determine the nature of the interactions. This method confirmed the presence of hydrogen bonds between linoleic acid and 2,5-dimethylpyrazine or oct-1-en-3-ol and also between molecules of oct-1-en-3-ol when the latter are present at high concentrations in lipids. The observations provided sufficient information to explain the behavior of oct-1-en-3-ol in biphasic solutions, but further work is needed to fully elucidate the nature of interactions between ethyl acetate or 2,5-dimethylpyrazine and lipids and also to explain the behavior of these compounds in biphasic solutions. JAOCS 75, 441-445 (1998).KEY WORDS: Aroma compound, fatty acids, Fourier transform infrared spectroscopy, interaction, liquid/liquid partition coefficient, tetradecane.Release and retention of aroma compounds are governed by the same physicochemical properties, and they determine the sensory qualities of foodstuffs and extraction ease of aroma compounds. Indeed, these characteristics are linked to the partition of volatiles in the different phases of food or biological media and also depend on the interactions that occur between aroma compounds and constituents of each phase. Therefore, determining the kind of interactions that occur in each phase is of great interest. It would help us to understand the phenomena involved in the perception of aroma compounds in emulsions or to explain the difficulties encountered in the extraction of volatiles from a biphasic system. Much has been done to reach this goal by measurement of thermodynamic equilibria in simple model solutions (1-3), but little research has been done on complex systems, and moreover, the nature of binding involved has not been clearly demonstrated. Knowledge of molecularlevel phenomena is now required to understand and predict interactions.Our aim was to show the type of interactions that occur between volatiles and lipids to explain the behavior of aroma compounds in biphasic solutions. To reach this goal, we studied the interactions between aroma compounds and constituents of biphasic solutions. The results concerning the factors that can affect the volatility of the aroma compounds have already been published (4). They have shown the importance of the presence of fatty acids in the medium for the vapor/liquid partition coefficient and also for the interactions between volatiles and substrates. The vapor/liquid partition coefficient measurem...

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Section: Resultsmentioning

confidence: 95%

Interactions between volatiles and lipids in complex systems

Thanh

Goubet

Quéré

et al. 1998

J Americ Oil Chem Soc

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“…Research on the ethanol distribution over the aqueous phase and organic phases of benzene and toluene has reported the distribution coefficients and selectivities as 0.058 and 115, and 0.040 and 100, respectively 11) . For another work these equilibrium parameters in the xylene _ ethanol _ water system was measured as 0.03 and 91, respectively 8) . Aromatic solvents show low distribution coefficient and high separation selectivity.…”

Section: Solvent Selectionmentioning

confidence: 99%

“…Liquid-liquid equilibrium data for ethanol, water and several organic liquids have been measured at different temperatures 7), 8) . Equilibrium distribution coefficients, defined as the concentration ratio of ethanol in the solvent phase relative to the aqueous phase, have been measured for ethanol, butanol, and acetone in various solvents, and the separation factors, defined as the distribution coefficient ratio of ethanol relative to water, have been calculated to evaluate the economic characteristics of extraction 9) .…”

Section: Introductionmentioning

confidence: 99%

Extraction Equilibrium of Ethanol for Bioethanol Production — Solvent Selection and Liquid-liquid Equilibrium Measurement —

Habaki

Tabata²,

Kawasaki

et al. 2010

J. Jpn. Petrol. Inst.

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Ethanol distributions between selected organic and aqueous phases were measured for recovery and concentration of bioethanol from fermented solution. The strategy of solvent selection was based on the background of biofuel production, and m-xylene was selected as the primary solvent and capric acid, 1-hexanol and 2-ethyl hexanol secondary solvents were utilized to enhance the ethanol solubility. The extraction performance was evaluated through the liquid-liquid equilibrium. m-Xylene showed low distribution coefficient of ethanol and high separation selectivity of ethanol relative to water. All secondary solvents increased the distribution coefficient. The separation selectivity was greatly reduced by capric acid, but was similar for 1-hexanol and 2-ethyl hexanol. The two phase region was smaller for 1-hexanol than for 2-ethyl hexanol, chosen as the best secondary solvent. Examination of the effects of 2-ethyl hexanol concentration in the solvent found that a small amount of 2-ethyl hexanol could enhance the distribution coefficient and maintain the separation selectivity constant. The measured liquid-liquid equilibria were estimated with the ordinary and modified UNIFAC methods. Both methods could predict the liquid-liquid equilibrium behaviors of the measured systems, but the modified UNIFAC method could show a better correlation. However, the water concentrations in the organic phases were estimated to be larger than the measured values if the measured concentrations were very low.

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“…Water can be co-extracted for two reasons --its solubility in the organic solvent and/or its interaction with the solute or the complex in the organic phase (Roddy and Coleman, 1981). The interaction can be considered to be hydration of the alcohol/solvent complex or the complexing of the hydrated alcohol.…”

Section: Yater Co-extractionmentioning

confidence: 99%

“…This was attributed to the formation of hydrates of the alcohol in the organic phase. Roddy and Coleman (1981) (1986) indicate that the self-association of the alcohol causes large changes in the specific molar volume and heat capacity of water in the organic phase and is enhanced by the presence of water.…”

Section: Yater Co-extractionmentioning

confidence: 99%

Separation of low molecular weight alcohols from dilute aqueous solutions by reversible chemical complexation

Arenson¹,

King²

1989

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The removal of alcohols from dilute solutions has traditionally been performed by distillation. Since this is an energy intensive process, a large amount of the total processing cost is due to the separation and purification of the alcohol. As an alternative to distillation, extraction is investigated from both a process and a chemistry point of view for several alcohols. The goals of the project were to find effective solvent systems for removal of alcohols and to investigate the interactions occurring in the organic phase during extraction. Ethanol was examined both as a model compound and because of the interest in its production by fermentation. The four butanols were extracted in order to investigate the differences in extraction of the various isomers. Several propanols and propanediols were used also. Phenols were found to provide much higher distribution ratios for extraction of ethanol than do other common solvents. Since most phenols are solids at room temperature, a mixed solvent system was employed. It was found that the type of diluent used could have a very large effect on the distribution ratio for the alcohol as well as on the water co-extraction and the solvent loss to the aqueous phase. In extracting the butanol isomers it was found that the indicated activity coefficients in the organic phase were approximately the same when large concentrations of m-cresol were present. This indicates 1 that the majority of the difference in the distribution ratios of the isomers is due to the differences in solvation of butanol in the aqueous phase. A mass-action-law model was used to obtain indicated stoichiometries for the complexes formed in the organic phase between the alcohol and m-cresol. Both multiple linear regression and curvefitting methods were used to find the stoichiometries. The results seem to indicate the presence of a 1:1 alcohol:m-cresol complex with solvation modifications due to the changing concentrations of the components of the organic phase. From the complex formation constants at different temperatures, the enthalpy of complex formation was calculated for the interaction between ethanol and m-cresol. 2 i DEDICATION To Shelley for making it all worthwhile ii ACKNOWLEDGMENTS I would like to acknowledge the support I have received from Professor C. Judson King. His knowledge and experience were invaluable during my graduate career. He allowed both the freedom to pursue ideas and the guidance to keep from straying to far.

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Distribution of ethanol-water mixtures to normal alkanes from C6 to C16

Cited by 19 publications

References 5 publications

Interactions between volatiles and lipids in complex systems

Interactions between volatiles and lipids in complex systems

Extraction Equilibrium of Ethanol for Bioethanol Production — Solvent Selection and Liquid-liquid Equilibrium Measurement —

Separation of low molecular weight alcohols from dilute aqueous solutions by reversible chemical complexation

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