Thermal behaviour and binary phase diagram of (S)-(+)-4,4'-(1-methyl-1,2-ethandiyl)-bis-(2,6-piperazinedione) (dexrazoxane), a cardioprotective agent, and of its (R)-(-)-enantiomer.

The binary phase diagram of (S)-(+)-4,4'-(1-methyl-1,2-ethandiyl)-bis-(2,6-piperazinedione), 1 (dexrazoxane), a cardioprotective agent, and of its (R)-(-)-enantiomer, 2, has been investigated by differential scanning calorimetry (DSC); the equimolecular mixture of 1 and 2 corresponds to a racemic compound (racemate) whose melting point is higher than that of the enantiomers. Thermal behaviour (DSC) is examined and discussed in comparison with the data obtained by other physical methods (IR spectroscopy and X-ray powder diffraction).