THE CRYSTAL STRUCTURES OF d-PINITOL AND l-QUEBRACHITOL BY LOW-TEMPERATURE X-RAY DIFFRACTION

The crystal and molecular structures of d-pinitol and l-quebrachitol were determined from low temperature x-ray diffraction data. Pinitol crystallizes in an orthorhombic system, P2₁2₁2₁ (Z=4), with unit cell dimensions of a=6.8345(8) Å, b=9.3233(10) Å, and c=12.8911(14) Å. Quebrachitol crystallizes in a monoclinic system, P2₁ (Z=2), with unit cell dimensions of a=6.6289(4) Å, b=7.1895(4) Å, c=8.6843(5) Å, and β=90.5690(10)°. No unusual bond lengths or valence angles are present within either structure. Both rings are in chair conformations, with the majority of the pendent groups in equatorial orientations. As found for many compounds with multiple hydroxyl groups, the structures have extensive networks of hydrogen bonds. Both structures have infinite chain sequences of hydrogen bonds incorporating the O-1 and O-4 hydroxyl groups and finite chain sequences incorporating the other hydroxyl groups.