Temperature Dependence of Limiting Activity Coefficients, Henry’s Law Constants, and Related Infinite Dilution Properties of Branched Pentanols in Water. Measurement, Critical Compilation, Correlation, and Recommended Data

Abstract

Limiting activity coefficients (γ 1 ∞ ) of six branched pentanols (2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, and 3-methyl-2-butanol) in water were measured at several temperatures covering the range from the melting to the normal boiling point of water. Five experimental techniques, namely, inert gas stripping, headspace analysis in two variants, the classical and the relative, Rayleigh distillation, and the method of circulation still, were employed for the purpose. A comprehensive review is further presented of experimental data on the limiting activity coefficients, γ 1 ∞ , infinite dilution partial molar excess enthalpies (H j 1 E,∞ ), and heat capacities (C j p,1 E,∞ ) of these aqueous solutes. Since H j 1 E,∞ data for 2-methyl-1-butanol in water are lacking in the literature, they were also determined in this work. For each pentanol isomer, the compiled data were critically evaluated and together with the data measured in this work correlated with a suitable model equation providing adequate simultaneous description of the equilibrium measurements and the calorimetric information. As a result, a recommended thermodynamically consistent temperature dependence of γ 1 ∞ , H j 1 E,∞ , and C j p,1 E,∞ of superior accuracy was established in the range from the melting point to the normal boiling point of water. In addition, by employing literature data on the respective residual properties of pure pentanols, analogous recommendations were derived also for the temperature dependence of the Henry's law constants, hydration enthalpies, and hydration heat capacities. Variation of these various infinite dilution thermodynamic properties with temperature and pentanol branching is briefly discussed. Furthermore, the performance of five predictive approaches to estimate γ 1 ∞ (T) of aqueous pentanols was tested.

Thermal and Volumetric Properties of Some C5 and C6 Alkanones at Infinite Dilution in Water

“…Hydration heat capacity of equi-structured alkanones and alkanols: points are experimental data for ■, 2-butanone/2-butanol; ●, 2-pentanone/2-pentanol; ▲, 3-pentanone/3-pentanol; ▼, 3-methyl-2-butanone/3-methyl-2-butanol; ⧫, 2-hexanone/2-hexanol; the line is Δ hyd C p ,1 (alkanones)/(J·K –1 ·mol –1 ) = Δ hyd C p ,1 (alkanols) /(J·K –1 ·mol –1 ) – 113.…”

“…Reliable experimental data on thermodynamic properties of volatile organic compounds (VOCs) at infinite dilution in water, such as limiting activity coefficient γ 1 ∞ , Henry’s law constant K H , limiting partial molar excess enthalpy H̅ 1 E,∞ , limiting partial molar (excess) heat capacity C̅ p,1 ∞ ( C̅ p,1 E,∞ ), and limiting partial molar (excess) volume V̅ 1 ∞ ( V̅ 1 E,∞ ), are of vital importance for numerous industrial and theoretical applications, in particular for design and control of thermal separation processes, for understanding the transport and fate of these substances in the environment, and for development of prediction methods and testing of solution theories. Over two past decades we have been greatly engaged in systematic measurements of these properties providing thus a bulk of data for various classes of VOCs, including aromatic and/or halogenated hydrocarbons, − alkanols, − phenols, ethers, esters, , nitrocompounds, nitriles, − amides, amines, nitrogen heterocyclic compounds, , and others. Continuing our long-term effort, this work focuses on ketones.…”

Air–Water Partitioning of C5 and C6 Alkanones: Measurement, Critical Compilation, Correlation, and Recommended Data

“…These uncertainties comprise contributions from all possible sources of error, both random and systematic. To estimate them for literature data, we followed the policy described and routinely applied by us previously. − In brief, the first estimates of the uncertainties were based on information given in the original source of data, our own experience with various experimental methods, and their detailed applicability analyses. When a comparison of correlation residuals to the initially assigned uncertainties indicated that the true uncertainties of some data were significantly greater than those assumed (probably because of systematic errors), the values of the uncertainties were subsequently increased by trial and error in order to obtain the coherence of all data in the statistical sense.…”

“…C (8) with data being weighted according to their standard uncertainties u(G 1,i ), u(H 1,i ), and u(C p , 1,i ). These uncertainties comprise contributions from all possible sources of error, both random and systematic.…”

“…A comprehensive critical compilation of literature K aw and γ 1 ∞ data as well as respective hydration and dissolution thermal data is further carried out, and all of the available information is correlated simultaneously for each solute by a three-parameter thermodynamically founded equation. Using this well-established thermodynamically consistent approach − allows us to discriminate between disagreeing data and present recommended temperature dependences for K aw and γ 1 ∞ . The results thus obtained are further used to disclose and discuss the effects of the molecular structure of alkanones on their K aw and γ 1 ∞ values and test the performance of existing methods to predict these values.…”