The crystal structure of D-threitol at 119 K and 198 K

A sample of DL-threitol, C4H10O4 (Sigma Chemical Co.), on recrystallization provided crystals of D- and L-threitol. The crystal structure was determined at 119 K and 298 K. The space group of D-threitol is P3(1)21, with three molecules in a unit cell at 119 K [298 K] of a = 10.0995(5) [10.1405(8)], c = 4.8407(4) [4.8767(4)] A. The final agreement R-factor was 0.050 for 302 intensities [0.069 for 244 intensities]. The molecules have the straight carbon-chain conformation with twofold axial symmetry. The hydroxyl groups are hydrogen bonded in infinite chains extending in the direction of the threefold screw axis. One of the hydroxyl hydrogens is twofold disordered, so that alternate chains have reversed donor-acceptor directions.