E. Kusters et al., THERMAL TRANSFORMATION OF A CHIRAL, NON-RACEMIC EPOXIDE INTO A CONGLOMERATE - A CASE-STUDY, Journal of thermal analysis, 41(5), 1994, pp. 1183-1189
Formation of conglomerates is of general interest because they offer t
he possibility of enantiomeric separation by preferential crystallizat
ion. A surprising result was obtained for the chiral epoxide ,2,7,7a-t
etrahydro-3-methoxynaphth-(2,3b)-oxirene, for which we have shown that
the racemate crystals of a non racemic mixture can be easily transfor
med into a conglomerate by gentle heating and cooling within a defined
temperature range. This transformation is not possible with the pure
racemic mixture. Thus the enantiomeric excess seems to be the driving
force for the conglomerate formation. Experiments have been carried ou
t on analytical and preparative scale. Non racemic mixtures have been
charaeterized by high pressure liquid chromatography on chiral station
ary phase and crystal transformation has been monitored with different
ial scanning calorimetry (DSC) and infrared spectroscopy (IR).