The objectives of this study were (i) to isolate and characterize mannitol hydrate, and (ii) to solve its crystal structure from high-resolution synchrotron X-ray powder diffraction data. Mannitol hydrate was prepared by freeze-drying aqueous mannitol solutions (5% w/v) under controlled conditions. X-ray powder diffractometry, differential scanning calorimetry, and thermogravimetric analyses indicated that mannitol exists as a hemihydrate (C6H14O6 · 0.5H2O). Synchrotron data were collected on the X3B1 beamline at the National Synchrotron Light Source. The simulated annealing program PSSP was used to solve the structure, which was subsequently refined by Rietveld analysis using the program package GSAS. The compound crystallizes in space group P1, with a = 9.8963 Å, b = 10.5424 Å, c = 4.7860 Å, α = 102.589°, β = 86.092°, and γ = 116.079°. The unit cell contains two dissimilar D-mannitol molecules and one water molecule, forming a hydrogen bonding pattern significantly different from that seen in the anhydrous polymorphs.
Bibliographical noteFunding Information:
Research was performed in part at the National Synchrotron Light Source at Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences. The SUNY X3 beamline at NSLS was previously supported by the Division of Basic Energy Sciences of the U.S. Department of Energy under Grant DE‐FG02‐86ER45231.
- Crystal structure
- Physical characterization
- Thermal analysis
- X-ray diffractometry