Enthalpic discrimination of R‐ and S‐limonenes in nonpolar solvents at 298.15 K

Abstract

Enthalpies of mixing of R- and S-limonene in non-polar solvents in the entire range of mole fractions were measured at 298.15 K. The enthalpies of mixing were negative for all concentrations in dilute concentration, but increased by increasing the concentration of limonenes in solutions. Ultimately positive excess enthalpies were shown in high concentration. Enthalpies of mixing were compared with theoretical estimation by COSMO-RS.

Thermodynamic properties of chiral fenchones in some solutions at T=298.15K

“…The UNIFAC method for (S-fenchone + ethanol) shows good agreement with the experimental results of 1109. 16 and 1114.78 J Á mol À1 , respectively. The UNIFAC result was 0.5% larger than the experimental results, but the absolute estimated values for the other three systems were comparatively smaller than the experimental results.…”

“…This indicates that the number of benzene molecules surrounding the fenchone molecule is much greater than that of cyclohexane molecules, and the degree of effect from the benzene solvent becomes larger than that of the cyclohexane solvent. The polar solvent of ethanol might be different as non-polar solvents as occurs in chiral limonene systems [16]. However the sequence b in equation (3) for enthalpic stabilities of (R + S)-fenchone in different solvents is same as that of enthalpies of mixing of (S-fenchone + solvents).…”

“…To elucidate stereospecific intermolecular interactions arising from the chiral structures of molecules and to understand chiral discrimination based on structural properties of liquids and solutions, the thermodynamic properties of mixing of many couples of (R)-and (S)-enantiomers, and enantiomers in polar and non-polar solutions were systematically studied in our laboratory [5][6][7][8][9][10][11][12][13][14][15][16]. Non-polar chiral compounds of chiral limonenes in whole concentrations of ethanol solutions have been investigated [14], and enthalpic behaviours of chiral limonenes in non-polar solvents of benzene, hexane, cyclohexane, and carbon tetrachloride have been determined and their unique concentration dependence reported [15,16]. Those solutions showed unique concentration dependence.…”