Interactions diastereoisomeres d'enantiomeres en phase liquide - II

Thermodynamic properties of ethanol solution of chiral camphors and its derivatives

“…The enthalpies of mixing of enantiomers of 2,3-dihydroxylbutanedioic acid, threonine, and alanine were reported by Takagi et al [1]. Some investigators have studied the problem of chiral interaction [2][3][4][5] in recent years. Previous calorimetric work in our laboratory includes measurement of enthalpies of mixing for 34 binary liquid chiral systems [6][7][8][9][10].…”

“…All enthalpies of mixing were exothermic over the entire range of the mole ratio of heterochiral camphor derivatives. Here f is defined as the mole fraction of the pseudobinary solution of each chiral compound, as shown in equation (2). The mixing process of the ethanol solution of R-and S-camphor derivatives showed a enthalpic stabilization of heterochiral contacts compared to each of the homochiral ones over the whole range of composition at T = 298.15 K. Excess enthalpies on mixing are less exothermic than those at a higher concentration of camphor derivatives in solutions, as shown in figures 4 to 8.…”

Enthalpic changes on mixing two couples of S- and R-enantiomers of benzyl-(1-phenyl-ethyl)-amine, 1-phenylethylamine, 1-phenyl-ethanol, butyric acid oxiranylmethyl ester, 4-methyl-[1,3]dioxolan-2-one, 2-chloro-methyloxirane and 3-hydroxyisobutyric acid methyl ester at T=298.15K

“…Takagi et al [1] discovered in 1966 that the small enthalpies of mixing of two enantiomers of the same compounds can be determined by microcalorimetry. Thereafter, the influences of stereospecific interactions on cohesive energies and densities of liquid state have been evaluated by others [2][3][4][5].…”

Optical Rotation of Noncovalent Aggregates

“…It has been known for some time that the nonlinear concentration dependence of [α] D in mixtures of two enantiomers can be attributed to the association of chiral species in solution, referred to as the Horeau effect . More recently, polarimetry was used to estimate dimerization equilibrium constants .…”