No abstract

No abstract

No abstract

Dilution enthalpies of two penicillamine enantiomers, namely, d-penicillamine, l-penicillamine, and their racemate d,l-penicillamine, in N,N-dimethylformamide (DMF) + water mixtures of various compositions have been determined at 298.15 K respectively, using an isothermal titration calorimeter (MicroCal ITC200). According to the McMillan–Mayer theory, homochiral enthalpic pairwise interaction coefficients (h XX) of the three penicillamines in DMF + water mixtures of different mass fractions (w DMF = 0 to 0.3) have been calculated regressively. It is found that h XX coefficients of each enantiomer and their racemate change increasingly with w DMF to the maxima at w DMF = 0.20 and then decrease relatively rapidly, which follows the order h LL > h DD ≈ h RR > 0 (R represents the racemate mixture of penicillamine). The results are discussed from the point of view of competitive equilibrium between hydrophobic and hydrophilic interactions in solutions.

No abstract