Thermodynamics Research Center / ThermoML | Thermochimica Acta

ABSTRACT

Both the S enantiomer and the racemic (RS) forms of 2-(2-nitro-1-phenylethyl)-1,3-diphenyl-propane-1,3-dione (1) have been obtained from the same reaction media by fractional crystallization from toluene.First, the racemic compound, (R,S)-1, was precipitated (mp. 159.7.C), then, from the filtrate, (S)-1 (mp.135.6.C) was crystallized. The absolute configuration (S) and crystal structure of (S)-1 has been solved bysingle crystal X-ray diffraction (R = 0.0377). (S)-1 crystallizes in the orthorhombic crystal system (spacegroup P212121(19), a = 10.6377(2)centsaA, b = 11.4348(2)centsaA, c = 31.3543(6)centsaA, Z = 8, Z = 2). Powder XRD patternof the racemic crystal (R,S)-1 could be indexed in the orthorhombic space group Pbca (61) (a = 22.18(7)centsaA,b = 17.08(3)centsaA, c = 9.96(3)centsaA, Z = 8, Z = 1). Differences in secondary bonding interactions and crystal stabilityof both (S)-1 and (R,S)-1 were evaluated on the basis of their FTIR spectra, melting points, and enthalpiesof fusion. The expected eutectic-type binary melting phase diagram of (S)-1 and (R,S)-1 crystals hasbeen constructed based on differential scanning calorimetric (DSC) measurements and calculation of theliquidus curves according to the combination of the simplified Schroder.van Laar and Prigogine.Defayequations.