Effect of salt on the distribution of acetic acid between water and organic solvent

Abstract

Equlllbrlum dlstrlbutlon data for three Important systems, water-ethyl acetate-acetic acld-sodium sulfate, water-2-ethylhexanol-acetlc acid-sodlum sulfate, and water-methyl ethyl ketone-acetlc acld-sodium sulfate, at 30 OC are presented. Empirical correlatlons are obtalned to represent these experimental data. Wlth an Increase In the salt concentration, the dlstrlbutlon coefflclent of acetic acid Increases, showing the "saltlng-out" effect. Wlth the solvents ethyl acetate and P-ethylhexanol the saltlng-out coefflclent decreases wlth an Increase In the acetlc acld concentratlon, whlle wlth the solvent methyl ethyl ketone the salting-out coefflclent Increases wlth an Increase In the acetic acld concentratlon. Thls change In salting-out coefflclent wlth acetic acld concentratlon Is explalned on the basls of solvent solublllty, saltlng-out of the solvent, and the solvent afflnlty for the acetlc acld.The distribution data for the water-acetic acid-solvent system are available in the literature for many organic solvents ( 7-3). However, very often, in practice, the aqueous streams contain salts such as sodium sulfate. The effect of salt on the distribution of acetic acid between water and an organic solvent has thus a direct engineering application.Swabb and Mongan (4) have studied the salt effect in the system water-isopropyl ether-acetic acid-sodium sulfate.McAteer et ai. (5) have studied the water-methyl isobutyl ketone-acetic acid-sulfuric acid system. The effect of lithium chloride, sodium chloride, and potassium chloride on the water-acetic acid-benzene system has been studied by Eisen and Joffe (6). the effect of magnesium chloride on the same system has been studied by Desai and Eisen (7). However, data are not available for the salt effect with such useful solvents as ethyl acetate, 2-ethylhexano1, and methyl ethyl ketone. In the present work, therefore, the effect of sodium sulfate on the distribution of acetic acid between water and each of the above-mentioned solvents was studied.The electrostatic theories explain the sat effects on the basis of the ateration in the dielectric constant of the solution. Debye and McAulay (9), Debye (IO), and Butler (11) have derived equations for the activity coefficient of nonelectrolytes in dilute salt solutions. These equations predict that satingout will occur if the dielectric constant of the nonelectrolyte solution is less than that of water, and salting-in if the reverse is true. The theories predict that the logarithm of the activity coefficient of the nonelectrolyte is a linear function of the ionic strength.According to the internal pressure concept proposed byTammann (72) and applied by McDevit and Long (73), the contraction in total volume upon the addition of salt to water can be thought of as a compression of the solvent. This compression makes it more difficult for the introduction of a molecule of nonelectrolyte, and this results in salting-out. An increase in total volume upon the addition of a sat wouM produce the counter effect known as salting-in. Semiqua...

Rapid Quantification of Major Volatile Metabolites in Fermented Food and Beverages Using Gas Chromatography-Mass Spectrometry

“…We choose ethyl acetate as the solvent for extraction of volatile compounds from water-based samples because it has very low solubility in water (8.3 mg/100 mL) [ 25 ] and it has high partition co-efficient for ethanol, acetic acid and other volatiles in aqueous solution [ 20 ]. In addition, anhydrous NaCl was added to the sample during extraction in order to increase the polarity of the aqueous layer and maximise extraction of volatile compounds [ 26 ]. By comparing samples extracted in presence and absence of NaCl, we observed a much better reproducibility and accuracy of analysis when NaCl was used (data not shown).…”

Selective N1-Alkylation of 2′-Deoxyguanosine with a Quinolinyl Quinone Methide

“…One rationale for the observed salt effect may be the salt-induced phase separation in aqueous DMF – . The NaCl-induced phase separation could cause dG and acetate 5 to partition differently in these phases, resulting in a possible biphase reaction mechanism , .…”

“…One rationale for the observed salt effect may be the salt-induced phase separation in aqueous DMF – . The NaCl-induced phase separation could cause dG and acetate 5 to partition differently in these phases, resulting in a possible biphase reaction mechanism , . Alternatively, the increased ionic strength with the addition of NaCl may directly suppress the rate of the elimination of the acetate group of 5 because the negatively charged acetate was produced in the formation of the neutral QM intermediate under buffered conditions , .…”

“…Thus, to fully account for the changed ratio of 6 to 7 in Figure 3, the addition of salt could also impact the rates of QM hydrolysis and dG alkylation. One rationale for the observed salt effect may be the saltinduced phase separation in aqueous DMF (28)(29)(30). The NaClinduced phase separation could cause dG and acetate 5 to partition differently in these phases, resulting in a possible biphase reaction mechanism (28,29).…”

The Technical and Energetic Challenges of Separating (Photo)Electrochemical Carbon Dioxide Reduction Products

“…Other products of potential interest, such as acetic acid, acetone, isopropanol and methanol, have been salted out from water in the presence of a third C 4+ organic-phase solvent such as butanone, cyclohexane or 2-ethylhexanol (Shah and Tiwari, 1981;Hasseine et al, 2009). As noted previously, however, this third solvent must then be separated from the product of interest.…”