Crystal structure of propylthiouracil determined using high-resolution synchrotron X-ray powder diffraction

The crystal structure of propylthiouracil, a drug used in the treatment of hyperthyroidism, was determined by means of high-resolution synchrotron X-ray powder diffraction data. The Rietveld method was employed to refine the structure. This drug crystallizes in an orthorhombic (Pcab) space group, with unit cell parameters a = 28.67338(23) A, b = 11.15287(6) A, c = 10.66821(5) A, V = 3411.59(4) A3, Z = 16, Z[prime or minute] = 2, M = 170.23 g mol-1, [small rho]calc = 1.3258(1) g cm-3. The goodness-of-fit and R-factors were, respectively: [small chi]2 = 1.599, RBragg = 1.57%, Rwp = 8.85% and Rexp = 5.53%. Four hydrogen bonds involving the atoms N(6)-H(12)S(39), N(19)-H(21)O(41), N(27)-H(33)S(18) and N(40)-H(42)O(20) form a network of molecular aggregates in propylthiouracil.