Structure of beta-trimyristin and beta-tristearin from high-resolution X-ray powder diffraction data

The crystal structures of beta-1,2,3-tritetradecanoylglycerol (beta-trimyristin or beta-MMM) and beta-1,2,3-trioctadecanoylglycerol (beta-tristearin or beta-SSS) have been determined from high-resolution synchrotron X-ray powder diffraction data. Grid search and Rietveld refinement have been used to determine and refine the structure, respectively. Both substances crystallize in space group P1; with Z = 2. The unit-cell parameters for beta-MMM are a = 12.0626 (6), b = 41.714 (1), c = 5.4588 (3) A, alpha = 73.388 (4), beta = 100.408 (5) and gamma = 118.274 (4) degrees. For beta-SSS the unit-cell parameters are a = 12.0053 (7), b = 51.902 (2), c = 5.4450 (3) A, alpha = 73.752 (5), beta = 100.256 (6) and gamma = 117.691 (5) degrees. Soft-distance restraints have been applied to the molecules during refinement. For beta-MMM the final R(p) value obtained is 0.053 and for beta-SSS the final R(p) value is 0.041.