Henry’s Constants of 2-Ketones in Aqueous Solutions Containing Inorganic or Quaternary Ammonium Salts

Abstract

Henry’s constants of 2-propanone, 2-butanone, 2-pentanone, 2-hexanone, and 2-heptanone in aqueous solutions containing inorganic salts or quaternary ammonium salts were determined at temperatures between 313 and 343 K, and salt ionic strengths below 5.0. Our data show that inorganic salts generally salt-out the 2-ketones, whereas quaternary ammonium salts generally salt-in the 2-ketones. However, 2-propanone is salted-out by both types of salts. We have also extended a published model based on dilute solution theory to solutions containing two inorganic salts, as well as to solutions containing quaternary ammonium salts. We show that it is possible to correlate all data for salting-out behavior using a single salt-effect parameter for each system. Salting-in behavior can also be correlated with a single parameter, although agreement with experiment is not as good as in the case of salting-out behavior. This is because the model does not explicitly account for the role of dispersion forces in these systems, which may be inferred from the trends exhibited by the salt-effect parameter as the size of the 2-ketone increases in solutions containing quaternary ammonium salts.

Receptacle Model of Salting-In by Tetramethylammonium Ions

“…This is in qualitative agreement with the experimental value of k S = −0.24 for the salting-in of the benzene in aqueous solution of TMA–bromide2. The ΔΔ G value slightly decreases with the hydrophobe size as shown experimentally for k S , for example, for hydrocarbon gases9, or 2-ketones8 in aqueous TMA salt solutions (Figure 2). The model correctly captures the trends of k S with the size of the nonpolar solute for both salting-in and salting-out salts.…”

“…9) are shown by dashed line, and the data for 2-ketones (from Ref. 8, 39) are shown by solid lines. n denotes the number of carbon atoms in a molecule.…”

“…For example, tetraalkylammonium salts2, 8, 9, 14–16 tend to favor dissolving hydrophobes in water. This is called salting-in .…”

“…In some cases, the same salt will salt–out small hydrophobes (positive k S ), but will salt–in large hydrophobes8.…”

Development of a quantitative method for headspace analysis of methylsulfanyl-volatiles from kiwifruit tissue

“…This points towards a "salting-in" effect that was also observed after MgSO 4 saturation. Each volatile can respond differently to varying salts or salt concentrations (Falabella & Teja, 2008;Yang & Peppard, 1994) and the use of MgSO 4 and CaCl 2 did not appear beneficial for MeS-volatile release from the kiwifruit matrix. However, when (NH 4 ) 2 SO 4 was used, best extraction yields for MeS-volatiles were achieved.…”