2-Phenylglycerol: crystal structure and conformational considerations pertaining to formation of its related oxetane

2-Phenylglycerol has been crystallized, structurally characterized, and its related conformations considered by ab initio calculations at the HF/6-31G * level. C9H12O3. 1/2H(2)O, P2(1), a = 5.8786(1), b = 28.6605(7), c = 10.55 53(3) Angstrom, beta = 90.187 (1)degrees at 100(1) K, Z = 8, R = 0.0424 for 5913 unique observed reflections. The asymmetric unit contains four molecu les of the title compound and two molecules of water. The structures are ch aracterized by extensive intermolecular hydrogen bonds. The packing is domi nated by a hydrophilic hydrogen bonded layer with the hydrophobic phenyl ri ngs forming a herringbone packed intermediate layer. Computational studies suggest that an increase in energy of about 13 kcal/mol can provide for sig nificant conformational flexibility, including the traversal of an orientat ion that is appropriately aligned with the reaction trajectory needed for c losure to the oxetane. Progression along this reaction coordinate, however, will probably require at least another 15 kcal/mol in the gas phase in ord er to bring the two S(N)2 species into a proximity which approaches that of the oxetane's C-O bond distance.