Similarity in structures of racemic and enantiomeric ibuprofen sodium dihydrates.

The crystal structures of two ibuprofen sodium dihydrates, racemic sodium (RS)-2-(4-isobutylphenyl)propanoate dihydrate or (RS)-NaIBDH, Na+.C13H17O2-.2H2O, and enantiomeric sodium (S)-2-(4-isobutylphenyl)propanoate dihydrate or (S)-NaIBDH, Na+.C13H17O2-.2H2O, have been determined in the space groups P-1 and P1, respectively. The unit cells of the two triclinic structures have similar lattice parameters and cell volumes. The constituent ions have similar coordination environments, but differ slightly in their hydrogen-bonding interactions. The dominance of the interactions between the O atoms and the Na+ cations explains the structural similarity of these two structures, despite the fact that one is heterochiral while the other is homochiral.